The phenomenon of a shot, its periods and their characteristics

A shot
is a complex complex of physical and chemical phenomena. The firing event can be divided into two stages - the movement of the projectile in the gun barrel and the complex of phenomena that occurs after the projectile leaves the barrel.

With a shot

is called the ejection of a bullet from the barrel under the action of powder gases formed during the combustion of a powder charge. The strike of the firing pin on the cartridge primer produces a flame that ignites the powder charge. In this case, a large amount of highly heated gases is formed, which create high pressure, acting in all directions with equal force. At a gas pressure of 250–500 kg/cm2, the bullet moves from its place and crashes into the rifling of the barrel, receiving a rotational movement. The gunpowder continues to burn, therefore, the amount of gases increases. Then, due to a rapid increase in the speed of the bullet, the volume of the behind-the-bullet space increases faster than the influx of new gases, and the pressure begins to fall. However, the speed of the bullet in the barrel continues to increase, since the gases, although to a lesser extent, still put pressure on it. The bullet moves along the bore with continuously increasing speed and is thrown outward along the axis of the bore. The entire firing process occurs in a very short period of time (0.001–0.06 s). Further, the flight of the bullet in the air continues by inertia and largely depends on its initial speed.

Initial bullet speed

is the speed at which the bullet leaves the barrel. The magnitude of the initial velocity of a bullet depends on the length of the barrel, the mass of the bullet, the mass of the powder charge and other factors. Increasing the initial speed increases the range of the bullet, its penetrating and lethal effect, and reduces the influence of external conditions on its flight. The backward movement of the weapon while firing is called recoil. The pressure of the powder gases in the barrel bore acts in all directions with equal force. The gas pressure on the bottom of the bullet causes it to move forward, and the pressure on the bottom of the cartridge case is transferred to the bolt and causes the weapon to move backward. During recoil, a pair of forces is formed, under the influence of which the muzzle of the weapon is deflected upward. The recoil force acts along the axis of the barrel, and the butt rest on the shoulder and the center of gravity of the weapon are located below the direction of this force, therefore, when firing, the muzzle of the weapon is deflected upward.

Recoil

small arms are felt as a push into the shoulder, arm or into the ground. The recoil action of a weapon is characterized by the amount of speed and energy it has when moving backwards. The recoil speed of a weapon is approximately the same number of times less than the initial speed of a bullet, how many times the bullet is lighter than the weapon. The recoil energy of a Kalashnikov assault rifle is low and is perceived painlessly by the shooter. Holding the weapon correctly and uniformly reduces the impact of recoil and improves shooting performance. The presence of muzzle brakes-compensators or compensators in weapons improves the results of burst fire and reduces recoil.

At the moment of firing, the barrel of the weapon, depending on the angle of elevation, occupies a certain position. The flight of a bullet in the air begins in a straight line, representing a continuation of the axis of the barrel bore at the moment the bullet leaves. This line is called the throwing line

.
When flying in the air, a bullet is acted upon by two forces: gravity and air resistance. The force of gravity deflects the bullet more and more downward from the throwing line, and the force of air resistance slows down the movement of the bullet. Under the influence of these two forces, the bullet continues to fly along a curve located below the throwing line. The shape of the trajectory
depends on the magnitude of the elevation angle and the initial speed of the bullet; it affects the range of the direct shot, covered, targeted and dead space. As the elevation angle increases, the trajectory height and the full horizontal range of the bullet increase, but this occurs to a certain limit. Beyond this limit, the trajectory height continues to increase, and the total horizontal range decreases.

The angle of elevation at which the total horizontal range of the bullet becomes greatest is called the angle of greatest range

. The maximum range angle for bullets of various types of weapons is about 35°. Trajectories obtained at elevation angles less than the angle of greatest range are called flat.

Straight shot

called a shot in which the trajectory of the bullet does not rise above the aiming line above the target along its entire length.

Direct shot range

depends on the height of the target and the flatness of the trajectory. The higher the target and the flatter the trajectory, the greater the direct shot range and, therefore, the distance at which the target can be hit with one sight setting. The practical significance of a direct shot is that in tense moments of battle, shooting can be carried out without rearranging the sight, and the aiming point in height will be chosen along the lower edge of the target.

The space behind cover that is not penetrated by a bullet, from its crest to the meeting point is called covered space

.

The higher the shelter and the flatter the trajectory, the larger the covered space. The part of the covered space in which the target cannot be hit with a given trajectory is called dead (unhittable) space. The greater the height of the shelter, the lower the height of the target, and the flatter the trajectory, the greater it is. The other part of the covered space in which the target can be hit is the target space.

Shot periodization

The shot occurs in a very short period of time (0.001-0.06 s.). When firing, there are four consecutive periods:

• preliminary;
• first, or main;
• second;
• third, or period of last gases.

Preliminary period

lasts from the beginning of the combustion of the powder charge until the bullet casing completely cuts into the rifling of the barrel. During this period, gas pressure is created in the barrel bore, which is necessary to move the bullet from its place and overcome the resistance of its shell to cut into the rifling of the barrel. This pressure is called boost pressure; it reaches 250 - 500 kg/cm2 depending on the rifling design, the weight of the bullet and the hardness of its shell (for example, for small arms chambered for the 1943 model cartridge, the boost pressure is about 300 kg/cm2). It is assumed that the combustion of the powder charge in this period occurs in a constant volume, the shell cuts into the rifling instantly, and the movement of the bullet begins immediately when the boost pressure is reached in the barrel bore.

First or main period

lasts from the beginning of the bullet’s movement until the complete combustion of the powder charge. During this period, combustion of the powder charge occurs in a rapidly changing volume. At the beginning of the period, when the speed of the bullet moving along the bore is still low, the amount of gases grows faster than the volume of the bullet space (the space between the bottom of the bullet and the bottom of the cartridge case), the gas pressure quickly increases and reaches its greatest value (for example, in small arms chambered for the sample cartridge 1943 - 2800 kg/cm2, and for a rifle cartridge 2900 kg/cm2). This pressure is called maximum pressure. It is created in small arms when a bullet travels 4 - 6 cm. Then, due to the rapid movement of the bullet, the volume of the behind-the-bullet space increases faster than the influx of new gases, and the pressure begins to drop, by the end of the period it is equal to approximately 2/3 of the maximum pressure. The speed of the bullet constantly increases and by the end of the period reaches approximately 3/4 of the initial speed. The powder charge is completely burned shortly before the bullet leaves the barrel.

Second period

lasts until the powder charge is completely burned until the bullet leaves the barrel. With the beginning of this period, the influx of powder gases stops, however, highly compressed and heated gases expand and, putting pressure on the bullet, increase its speed. The pressure decline in the second period occurs quite quickly and at the muzzle the muzzle pressure is 300 - 900 kg/cm2 for various types of weapons (for example, for a Simonov self-loading carbine - 390 kg/cm2, for a Goryunov heavy machine gun - 570 kg/cm2). The speed of the bullet at the moment it leaves the barrel (muzzle speed) is slightly less than the initial speed.

For some types of small arms, especially short-barreled ones (for example, a Makarov pistol), there is no second period, since complete combustion of the powder charge does not actually occur by the time the bullet leaves the barrel.

Third period

, or the period after the action of gases lasts from the moment the bullet leaves the barrel until the moment the action of the powder gases on the bullet ceases. During this period, powder gases flowing from the barrel at a speed of 1200 - 2000 m/s continue to affect the bullet and impart additional speed to it. The bullet reaches its highest (maximum) speed at the end of the third period at a distance of several tens of centimeters from the muzzle of the barrel. This period ends at the moment when the pressure of the powder gases at the bottom of the bullet is balanced by air resistance [1].

SMALL ARMS SHOOTING BASICS

INTRODUCTION

The need to improve the efficiency and quality of firearms training for law enforcement officers is dictated by the fact that in recent years the number of cases of the use of weapons in law enforcement practice has remained at a high level. This is caused by the increased scale of criminal manifestations, which are characterized by increased aggressiveness and cruelty, and increased opposition to law enforcement forces.

Firearms training is a critical component of a law enforcement officer's professional skills. The purpose of fire training is to develop the readiness of a law enforcement officer to skillfully and effectively use service weapons when performing operational and official tasks.

To achieve this goal, the textbook presents material that helps solve the main problems:

– formation of knowledge on the basics of internal and external ballistics of small arms;

– study of the material part of service weapons used by law enforcement officers;

– formation of skills in complex possession of various types of firearms;

– ensuring the readiness of law enforcement officers to lawfully suppress illegal actions using service weapons.

The training manual describes and depicts various methods of preparing to fire a pistol and methods of handling it when performing operational tasks by law enforcement officers.

This manual can be used when conducting practical classes and complex exercises in educational organizations in the disciplines “Fire training”, “Physical training”, “Tactical and special training”.

Users of the training manual can be teachers of fire, physical and tactical-special training of educational organizations, teachers, graduate students (adjuncts), students (cadets) of law universities studying in the field of training 40.03.01 “Jurisprudence”, as well as specialties 40.05.02 “Law Enforcement” activities" and 40.05.01 "Legal support of national security", as well as employees of non-governmental law enforcement organizations (private detectives, security companies and security services).

PART ONE

SMALL ARMS SHOOTING BASICS

Chapter I. GENERAL INFORMATION FROM INTERNAL BALLISTICS

Internal ballistics studies the movement of a bullet in the barrel under the influence of powder gases and all the phenomena that cause and accompany this movement. It is designed to solve the problem of giving the bullet the highest speed without exceeding the permissible pressure of the powder gases in the bore of the weapon.

Shot periods

With a shot

is the phenomenon of ejection of a bullet (projectile) from the barrel under the influence of the energy of powder gases. This phenomenon is characterized by the following features:

– high gas pressure (2 – 3 thousand or more kg/cm2);

– high temperature of powder gases (2000 – 3000 °C);

– short duration of the phenomenon (0.001 – 0.06 sec.);

– combustion of a powder charge in a rapidly changing volume.

A shot is a process of very rapid conversion of the chemical energy of gunpowder, first into thermal, and then into the kinetic energy of weapon movement.

The shot begins with the striker hitting the primer - the igniter. The impact causes an explosive transformation of the initiating or impact composition. In this case, hot gases in the form of a beam of flame penetrate through the seed holes of the cartridge case into the combustion chamber and ignite the powder charge.

Subsequent combustion of gunpowder is accompanied by the formation of a large amount of gases heated to 2000 - 3000 0C. The gases press with enormous force in all directions: on the walls of the cartridge case, its bottom and on the bullet. The bore is securely locked with a bolt. The pressure of the gases on the bottom of the cartridge case forces it to press against the bolt cup, the pressure on the walls of the case - to press tightly against the walls of the chamber, and the pressure on the bullet forces it to crash into the rifling of the barrel, move along its channel with increasing speed and fly out of the barrel. Let us immediately pay attention to the fact that the explosive transformation of gunpowder is usually called combustion, although this transformation lasts no more than 0.06 seconds. The fact is that high explosives, or crushing explosives, decompose hundreds of times faster than gunpowder. Thus, in comparison with them, the transformation of gunpowder can be considered as rapid combustion, but it is precisely this slowness of gunpowder that allows them to be used as propellants. Due to the slowness of decomposition, the projectile has time to move off long before it all turns into gases, therefore, at a relatively low pressure.

Rice. 1. Shot periods

These phenomena are divided into four periods (Fig. 1)

Po – boost pressure;

Pm – highest (maximum) pressure;

Pк and Vк – gas pressure and bullet speed at the moment of the end of gunpowder burning;

Pd and Vd – gas pressure and bullet speed at the moment of its departure from the barrel;

Vm – highest (maximum) bullet speed;

Patm. – pressure equal to atmospheric.

The period of the shot phenomenon, in which the powder charge burns in a constant volume to the amount necessary for the bullet to completely penetrate the rifling, is called the preliminary period

. It is characterized by the formation of forcing pressure (Pf). For small arms it is 250–500 kg/cm2.

RF =250 – 500 kg/cm2

Rice. 2. Pre-shot period

First,

or
main
, the period of the shot phenomenon, which is characterized by the combustion of a powder charge in a rapidly changing volume. It lasts from the moment the boost pressure is reached until the complete combustion of the powder charge. During this period, the gas pressure reaches its maximum value (Pmax). For small arms it reaches 2500 – 4000 kg/cm2. This pressure causes a significant acceleration of the movement of the bullet in the barrel bore, as a result of which the bullet space increases, therefore, despite the influx of new gases, the pressure begins to fall, reaching approximately 2/3 of the maximum pressure at the end of the combustion of the powder charge, and the speed of the bullet by the end of the period reaches approximately 3/4 of the initial speed.

Рmax = 2500 – 4000 kg/cm2

V2 = 3/4Vinitial

4 – 9 cm

Rice. 3. First, or main, period of the shot

Second period

shot phenomena. After the combustion of the powder charge, the influx of new gases stops, but since the gases have a large supply of energy, their expansion continues and, consequently, the speed of the bullet increases. This period lasts from the end of the combustion of the powder charge until the bullet leaves the barrel. At the end of the period, the pressure drops quickly and reaches a muzzle pressure of 300 - 900 kg/cm2 at the muzzle.

For some types of small arms, especially short-barreled ones (Makarov pistol), there is no second period, since complete combustion of the powder gas practically does not occur by the time the bullet leaves the barrel.

Pk=300 – 900 kg/cm2

Rice. 4. Second shot period

Third period

, or the gas aftereffect period, is characterized by the fact that the gases flowing out of the barrel after the bullet continue to affect it. When the bullet leaves the barrel, it is followed by a stream of gases, the speed of which is 2 to 3 times higher than the speed acquired by the bullet. These gases have some effect on the bullet, increasing its speed by 2 - 4 m/sec. At the same time, the weapon is significantly affected by the outflow of gases from the barrel, increasing the recoil speed by 20 - 25%. The period lasts from the moment the bullet leaves the barrel until the action of the powder gases on the bullet ceases. During this period, the pressure drops sharply. The speed of the bullet increases until the gas pressure on the bullet becomes equal to the air resistance and reaches its maximum (Vmax) at a distance of several tens of centimeters from the muzzle of the barrel.

R = Rathmospheric; V = Vmax

Rice. 5. Third period or period of aftereffect of gases

Initial bullet speed

Initial speed

is the speed at which the bullet leaves the barrel, that is, at the muzzle of the barrel. It is also called muzzle velocity. In fact, this speed also includes some increase in speed caused by the aftereffect of powder gases. This total speed is indicated by a Latin letter with a subscript zero distance indicator (V0). Initial speed is the most important ballistic indicator that determines the sharpness of the battle. The average speed is calculated using the formula:

Vav=L/t

where Vav – average speed; L – distance to target; t – time of flight of the bullet to the target.

When shooting from a rifled weapon, an increase in initial velocity is almost always desirable: the trajectory of the bullet straightens, and its kinetic energy increases. The magnitude of the muzzle velocity is indicated in the shooting tables and in the combat characteristics of the weapon.

The initial velocity is one of the main ballistic characteristics of a weapon. As the initial speed increases, the range of the bullet (projectile), the effectiveness of the fire, the penetrating and lethal force, and the direct shot increase.

The magnitude of the initial speed depends on many factors. The main ones are the following:

1. Bullet (projectile) weight. With increasing bullet weight for the same charge, the initial velocity decreases, and with decreasing weight it increases.

2. Charge weight. With increasing charge at the same weight of the bullet (projectile), the initial speed increases.

3. Barrel length. As the length of the barrel increases, the initial velocity increases, since the bullet (projectile) is exposed to gas pressure for more time. However, this increase in initial velocity with increasing bore occurs up to certain limits. With a very long barrel length, it may turn out that the force of the powder gases becomes less than the resistance force of the bullet (projectile) in the barrel bore. In this case, the speed of the bullet will begin to decrease.

4. Temperature and humidity of the powder charge. As the temperature of the powder charge increases, the burning rate of the powder increases, and therefore the maximum pressure and the initial speed. As the humidity of the powder charge increases, the burning rate and initial velocity decrease.

5. Shape and size of gunpowder. They have a significant impact on the burning rate of the powder charge, and therefore on the initial speed of the bullet. They are selected accordingly when designing weapons.

6. Loading density, that is, the ratio of the weight of the charge and the volume of the cartridge case with the bullet inserted. When the bullet is seated deeply, the loading density increases significantly, which can lead to a sharp surge in pressure when fired and, as a result, to rupture of the barrel, so such cartridges cannot be used for shooting. As the loading density decreases (increases), the initial bullet speed increases (decreases).

Flying a bullet in the air

The bullet, having received a certain initial speed when leaving the barrel bore, tends by inertia to maintain the magnitude and direction of this speed.

If the flight of a bullet took place in airless space and the force of gravity did not act on it, the bullet would move rectilinearly, uniformly and endlessly. However, a bullet flying in the air is subject to forces that change its flight speed and direction of movement. These forces are gravity and air resistance (Fig. 8).

Rice. 8. Forces acting on a bullet during its flight

Due to the combined action of these forces, the bullet loses speed and changes the direction of its movement, moving in the air along a curved line passing below the direction of the axis of the barrel bore.

The line that a moving bullet describes in space (its center of gravity) is called a trajectory

.

Typically, ballistics considers the weapon's trajectory above the horizon

– an imaginary infinite horizontal plane passing through the departure point (Fig. 9).

Rice. 9. Weapon Horizon

The movement of the bullet, and therefore the shape of the trajectory, depends on many conditions. To understand how its trajectory is formed in space, it is necessary to consider, first of all, how the force of gravity and the force of air resistance act on the bullet separately.

The action of gravity. Let's imagine that no force acts on the bullet after it leaves the barrel. In this case, as mentioned above, the bullet would move by inertia endlessly, uniformly and rectilinearly along the axis of the barrel bore; for every second it would fly the same distances with a constant speed equal to the initial one. In this case, if the barrel of the weapon were aimed directly at the target, the bullet, following in the direction of the axis of the barrel bore, would hit it (Fig. 10).

Rice. 10. The movement of a bullet by inertia (if there were no gravity and air resistance)

Let us now assume that only one force of gravity acts on the bullet. Then the bullet will begin to fall vertically down, like any freely falling body.

If we assume that the force of gravity acts on the bullet as it flies by inertia in airless space, then under the influence of this force the bullet will drop lower from the extension of the axis of the barrel bore - in the first second - by 4.9 m, in the second - by 19.6 m etc. In this case, if you point the barrel of a weapon at a target, the bullet will never hit it, since, subject to gravity, it will fly under the target (Fig. 11).

Rice. 11. The movement of a bullet (if it were affected by gravity, but not by air resistance)

It is quite obvious that in order for a bullet to fly a certain distance and hit the target, it is necessary to point the barrel of the weapon somewhere above the target. To do this, it is necessary that the axis of the barrel bore and the horizon plane of the weapon make a certain angle, which is called the elevation angle.

As can be seen in Fig. 11, the trajectory of a bullet in airless space, which is affected by gravity, is a regular curve called a parabola. The highest point of the trajectory above the weapon's horizon is called its apex. The part of the curve from the departure point to the top is called the ascending branch. This bullet trajectory is characterized by the fact that the ascending and descending branches are exactly the same, and the throwing and falling angles are equal to each other.

In Fig. Figure 12 shows two schemes for bringing a Makarov pistol into normal combat at a range of 25 m:

A – excess 12.5 cm;

B – exceeding 0.

Rice. 12. Exceeding PM trajectories

The excess of the trajectory above the aiming line is the shortest distance from any point on the trajectory to the aiming line.

The bullet trajectory is an unevenly curved curve in the vertical plane, which exceeds the aiming line.

Since the use of weapons involves firing at short distances, we are interested in the left half of the trajectory - up to 25 m. Knowing the parameters for exceeding the trajectory will help to quickly and correctly determine the aiming area. All domestic weapons have sighting according to the “A” pattern, although such aiming is more suitable for sports shooting.

In a combat situation, there is no time to calculate the excesses at various ranges, so it is more advisable to shoot the weapon according to scheme “B”, when the aiming point is the impact point. However, when shooting up to 10 m, the maximum excess is 5 cm, so in practice, with sufficient accuracy, the aiming point can be considered the point of impact. The figure clearly shows that at a distance of up to 25 m the trajectory is almost a straight line.

Considering that the bullet weighs only a few grams, the large braking effect that air has is quite obvious. During flight, a bullet spends a significant portion of its energy pushing air particles apart.

As shown in Fig. a photograph of a bullet flying at supersonic speed (over 340 m/s), an air compaction forms in front of its head (Fig. 13). From this compaction the head ballistic wave diverges in all directions. Air particles, sliding along the surface of the bullet and falling off its side walls, form a zone of rarefied space behind. In an effort to fill the resulting void, air particles create turbulence, resulting in a tail wave stretching behind the bottom of the bullet.

Rice. 13. A bullet flying at supersonic speed (over 340 m/sec.)

The compaction of air in front of the bullet's head slows down its flight; the rarefied zone behind the bullet sucks it in and thereby further enhances the braking; the walls of the bullet experience friction against air particles, which also slows down its flight. The resultant of these three forces is the air resistance force.

The enormous influence that air resistance has on the flight of a bullet can also be seen from the following example. A bullet fired from a Mosin rifle model 1891/30. or from a Dragunov sniper rifle (SVD) under normal conditions (with air resistance), has the greatest horizontal flight range of 3400 m, and when firing in airless space it could fly 76 km. Consequently, under the influence of air resistance, the trajectory of the bullet loses the shape of a regular parabola, taking on the shape of an asymmetrical curved line; the apex divides it into two unequal parts, of which the ascending branch is always longer than the descending one. When shooting at medium distances, we can conventionally take the ratio of the length of the ascending branch of the trajectory to the descending branch as 3:2.

Weapon Horizon

Rice. 20. Elevation angle and throwing angle

The throwing angle at which the horizontal range of the bullet is greatest is called the angle of greatest range

. For modern small arms, the value of this angle ranges from 30–35° depending on the weight and shape of the bullet.

Trajectories formed at throwing angles less than the angle of greatest range (0–35°) are called flat

.

Trajectories formed at throwing angles greater than the angle of greatest range (35–90°) are called hinged

.

Departure angle

is the angle formed by the direction of the axis of the barrel bore before the shot and at the moment the bullet leaves the bore. So, there is a certain relationship between the horizontal range of a bullet and the throwing angle. According to the laws of mechanics, the greatest horizontal flight range in airless space corresponds to a throwing angle of 45°. As the angle increases from 0° to 45°, the range of the bullet increases, and then with a further increase in angles from 45 to 90°, it decreases. The throwing angle at which the horizontal range of the bullet will be greatest is called the angle of greatest range.

When a bullet flies in the air, the angle of greatest range does not reach 45°; depending on the weight and shape of the bullet, its value for modern small arms ranges from 30 to 35°. The maximum range angle for a rifle when firing a light bullet is 35°

In most cases, law enforcement officers have to open fire to kill at ultra-short (0 - 5 m), short (5 to 25 m) and medium distances (from 25 to 100 m), at which shots from almost all types of weapons (pistols) , machine guns, machine guns, rifles) will be direct (pistols and revolvers are designed for shooting at a distance of up to 50 m). Direct shot

- this is a shot in which the trajectory of the bullet does not exceed the height of the target above the aiming line along its entire length.

Rice. 21. Floor and mounted trajectories

Rice. 22. Trajectory and its elements

The following trajectory elements are distinguished:

:

The departure point is the center of the muzzle, it is the beginning of the trajectory.

The weapon's horizon is a horizontal plane passing through the point of departure.

Elevation line - a line that is a continuation of the axis of the barrel of the aimed weapon before the shot.

Throwing line - a line that is a continuation of the axis of the barrel bore at the moment the bullet leaves.

The shooting plane is a vertical plane passing through the elevation line.

Elevation angle - the angle between the elevation line and the horizon of the weapon.

Throwing angle - the angle between the throwing line and the horizon of the weapon.

Launch angle is the angle between the elevation line and the throwing line.

The point of impact is the point of intersection of the trajectory with the horizon of the weapon.

Angle of incidence - the angle between the tangent to the trajectory at the point of impact and the horizon of the weapon.

Horizontal range - the distance from the point of departure to the point of impact.

The trajectory vertex is the highest point of the trajectory.

Trajectory height is the shortest distance from the top of the trajectory to the horizon of the weapon.

The aiming line is a straight line running from the shooter’s eye through the middle of the sight slot (at the level of the top edge of the rear sight) and the top of the front sight to the aiming point.

Aiming angle is the angle between the elevation line and the target line.

Target elevation angle is the angle between the aiming line and the horizon of the weapon.

Meeting angle is the angle between the tangent to the trajectory at the meeting point and the target surface.

The target point is the point at which fire is directed and bullets are aimed to hit.

Target line – a line connecting the departure point to the target point.

Meeting point – the point of intersection of the trajectory with the target or the surface of the obstacle.

Aiming point - the point of intersection of the aiming line with the target or target plane.

PART TWO

Chapter I. GENERAL INFORMATION

Types of cartridges

9 – mm cartridge with a lead bullet without a steel core

. There is no colored border at the point where the bullet and cartridge are attached. Produced by the Novosibirsk Low-Voltage Equipment Plant (bullet weight - 6.1 g, initial speed - 315 m/s), Tula Cartridge Plant (bullet weight - 6.86 g, initial speed - 303 m/s), Barnaul Machine Tool Plant (bullet weight – 6.1 g, initial speed – 325 m/s).

9 – mm cartridge with steel core

(marking 57 – H – 181C).
9 - mm high-impulse cartridge with a steel core
(PMM)
with increased penetration capacity
(markings 57 - H - 181CM; 7N16). Cartridge weight - 9.5 g, bullet weight - 5.6 g, sleeve length - 18 mm, cartridge length - 25 mm, initial bullet speed - 425 m/s. Steel core cartridges have a red border where the bullet and case are attached.

9 – mm cartridge with an expansive bullet

(SP – 7) has three modifications: one with a polyethylene plug in the head part and two with a hexagonal hole in the head part and cuts in the shell. The SP - 7 cartridge with a bullet weight of 4.1 g, a muzzle velocity of 420 m/s, a maximum powder gas pressure of 122.6 MPa (1250 kgf/cm2) is produced by the Klimovsky Stamping Plant; cartridge with a bullet weight of 6.1 g, an initial speed of 325 m/s - Barnaul Machine Tool Plant. A cartridge with an expansive bullet (cylindrical, expansive, with a lead core and a notched shell) is produced by the Novosibirsk NVA plant.

9 – mm cartridge with tracer bullet

(PT) is designed for firing from all types of weapons that use a standard cartridge for the Makarov pistol. The tracer bullet allows you to adjust the fire and provide a psychological effect (cartridge weight 9.6 g, bullet weight 5.7 g). A cartridge with a tracer bullet has a green border at the point where the bullet and cartridge are attached. Produced by the Novosibirsk NVA plant.

9 – mm cartridge for destruction of low-strength barriers

(SP – 8). The average bullet speed is 255 m/s, the maximum pressure of powder gases is 78.5 MPa (800 kgf/cm2), the bullet weight is 4.1 g. Produced by the Klimovsky Stamping Plant.

9 – mm armor-piercing cartridge

(BZhT) is produced by the Novosibirsk NVA plant (bullet weight 5.9 g).

9 – mm cartridge PBM 9x18. The bullet of the PBM 9x18 cartridge is semi-jacketed, with an exposed steel core and an aluminum jacket that fits the core. The bullet speed at a distance of 10 m from the muzzle is 470 – 480 m/s. The low mass of the bullet at a high initial speed (compared to the standard cartridge) increased the kinetic energy of the bullet when it met an obstacle at distances of up to 25 m. Moreover, due to the reduction in the mass of the bullet, the recoil impulse when firing is almost equal to the recoil impulse when shooting a standard 9 - mm PM pistol cartridge. A bullet from the PBM 9x18 cartridge penetrates a general-arms protective vest model 6B5-12 at a distance of 30 m with a probability of 100%, and a steel 5-mm sheet at a distance of 15 meters with a probability of 80%.

PISTLET

Disassembling and assembling the pistol

Disassembly of the pistol may be incomplete or complete. Incomplete disassembly

is carried out for cleaning, lubricating and inspecting the gun,
full
- for cleaning when the gun is heavily soiled, after leaving it in the rain or snow, when switching to a new lubricant, as well as during repairs.

Frequent complete disassembly of the pistol is not permitted.

, as it accelerates the wear of parts and mechanisms.

When disassembling and assembling the pistol, the following rules must be observed:

– disassembly and assembly should be carried out on a table, bench or on a clean mat;

– place parts and mechanisms in the order of disassembly, handle them carefully, avoid unnecessary force and sharp impacts;

– when assembling, pay attention to the numbering of parts so as not to confuse them with parts of other pistols.

Partial disassembly of the pistol should be carried out in the following order:

1. Remove the magazine from the base of the handle. Holding the pistol by the handle with your right hand, with the thumb of your left hand, pull the magazine latch back as far as it will go, while simultaneously pulling back the protruding part of the magazine cover with the index finger of your left hand, remove the magazine from the base of the handle (Fig. 46).

2. Check to see if there is a cartridge in the chamber, to do this, turn off the safety (move the flag down), move the bolt to the rear position with your left hand, put it on the bolt stop and inspect the chamber. Press the shutter stop with your right thumb and release the shutter.

Rice. 46. ​​Removing the magazine from the base of the handle

3. Separate the shutter from the frame (Fig. 47, 48). Taking the pistol in your right hand by the handle, with your left hand move the trigger guard down and, tilting it to the left, rest it against the frame so that it is held in this position. During further disassembly, hold it in position with the index finger of your right hand. With your left hand, move the bolt to its rearmost position and, lifting its rear end, allow it to move forward under the action of the return spring. Separate the bolt from the frame and put the trigger guard in its place.

4. Remove the return spring from the barrel (Fig. 49). Holding the frame with your right hand by the handle and rotating the return spring towards you with your left hand, remove it from the barrel. When removing the return spring from the barrel, the spring should be held by the coils with a smaller diameter - from the breech side of the barrel.

Rice. 49. Removing the return spring

Reassemble the pistol after partial disassembly in the reverse order:

1. Place the return spring on the barrel. Taking the frame by the handle in your right hand, with your left hand you must put the return spring onto the barrel with the end in which the outermost coil has a smaller diameter compared to other coils.

2. Attach the shutter to the frame (Fig. 50, 51). Holding the frame by the handle in your right hand and the bolt in your left, insert the free end of the return spring into the bolt channel and move the bolt to the rearmost position so that the muzzle of the barrel passes through the bolt channel and protrudes out. Lower the rear end of the shutter onto the frame so that the longitudinal protrusions of the shutter fit into the grooves of the frame, and, pressing the shutter against the frame, release it. The bolt, under the action of the return spring, vigorously returns to the forward position.

3. Turn on the fuse (raise the flag up).

Note.

To attach the shutter to the frame, it is not necessary to pull down and twist the trigger guard. At the same time, when moving the bolt to the rearmost position, it is necessary to lift its rear end up as far as possible so that the lower front wall of the bolt does not stick into the ridge of the trigger guard, which limits the movement of the bolt back.

4. Insert the magazine into the base of the handle (Fig. 52). Holding the pistol in your right hand, use the thumb and index finger of your left hand to insert the magazine into the base of the grip through the lower window of the base of the grip. Press the magazine cover with your thumb so that the latch (the lower end of the mainspring) jumps over the protrusion on the wall of the magazine; there should be a click. Hitting the magazine with the palm of your hand is not allowed.

Rice. 52. Installing a magazine at the base of the pistol grip

5. Check for correct assembly

pistol after partial disassembly. Turn off the fuse (move the flag down). Move the shutter to the rear position and release it. The shutter, having moved slightly forward, engages the slide stop and remains in the rear position. Pressing the bolt stop with the thumb of your right hand, release the bolt, which, under the action of the return spring, should vigorously return to the forward position, and the trigger should be cocked. Turn on the safety (lift the flag up), as a result of which the trigger should be released from the cocking mechanism and locked.

Complete disassembly

produce the pistol in the following order.

1. Partially disassemble the pistol.

2. Separate the sear and bolt stop from the frame. Take the pistol in your left hand, holding the trigger head with your left thumb and pressing the tail of the trigger with your index finger, smoothly release the trigger.

Use the rubbing protrusion to remove the hook of the sear spring from the bolt stop (Fig. 53). Using the index finger and thumb of your right hand, turn the sear forward until the flat on the right trunnion coincides with the slot of the trunnion socket in the frame, then lift the sear and bolt stop up and separate them from the frame (Fig. 54).

3. Separate the handle from the base of the handle and the mainspring from the frame. Using a cleaning blade, unscrew the screw and, moving the handle back, separate it from the base of the handle (Fig. 55). Pressing the mainspring with the thumb of your left hand to the base of the handle, move down and separate the mainspring bolt from the base of the handle and remove the mainspring from the boss of the handle base (Fig. 56).

Notes:

1. In combat conditions, if there is no wiping at hand, the screw can be unscrewed with a bolt stop reflector. 2. In pistols of the first releases, the mainspring is attached without a bolt.

4. Separate the trigger from the frame (Fig. 57). Holding the frame in your left hand and turning the trigger to the extreme forward position, use the index finger and thumb of your right hand to turn the trigger forward until the flats on its trunnions coincide with the slots in the trunnion sockets in the frame, move the trigger towards the barrel and remove it.

Rice. 57. Separating the trigger from the frame

5. Separate the trigger rod with the cocking lever from the frame (Fig. 58). Holding the frame in your left hand, lift the rear end of the trigger rod with your right hand and remove the pin from the trigger hole.

Rice. 58. Separating the trigger rod with the cocking lever from the frame

6. Separate the trigger from the frame (Fig. 59). Holding the frame in your left hand, pull the trigger guard down with your right hand, as is done when partially disassembling the pistol, turning the tail of the trigger forward, remove the trigger pins from the pin sockets in the frame and separate the trigger from the frame. Place the trigger guard in its place.

Rice. 59. Separating the trigger from the frame

7. Separate the fuse and firing pin from the bolt (Fig. 60). Taking the bolt in your right hand, turn the safety catch upward with the thumb of your left hand, then use the index and thumb of your left hand to move the safety catch out of the socket slightly to the side, turn it further back and remove it from the bolt socket.

Using light blows with the rear end of the bolt on the palm of your left hand, remove the firing pin from the bolt.

Rice. 60. Separating the safety and firing pin from the bolt

8. Separate the ejector from the bolt (Fig. 61). Place the bolt on the table (bench), with your right hand, using the rubbing protrusion, press the ejector pressure in and, at the same time, pressing the front part of the ejector with the index finger of your left hand and turning it around the hook, remove it from the groove, then carefully remove the pressure with the spring from the bolt socket .

Rice. 61. Separating the ejector from the bolt

9. Disassemble the magazine (Fig. 62). Taking the magazine in your right hand, use the thumb and forefinger of this hand to press the feeder spring towards the feeder, with your left hand remove the magazine cover by its protruding part and remove the feeder spring and feeder from the magazine body.

Rice. 62. Detaching the magazine cover

Reassemble the pistol after complete disassembly in the reverse order.

1. Assemble the magazine (Fig. 63). Holding the magazine body in your left hand so that the protrusion for the magazine latch is in front and at the top, insert the feeder into the magazine body with your right hand. Insert the feeder spring into the magazine body with the unbent end down and, pressing the spring with the thumb of your left hand, push the cover onto the curved ribs of the body with your right hand so that the bent end of the spring pops into the hole

In a split second, four shot periods

Firing from a 23-mm KS-23 gun
The word “shot” in artillery is used in several meanings and means: a set of processes occurring in the barrel of a firearm; a set of ammunition intended for firing from this weapon; the moment a bullet (projectile) leaves the bore of a weapon using the energy of gases formed during the combustion of a powder charge. In internal ballistics, the word “shot” is used in its first meaning.

The phenomenon of a shot is a set of mechanical, physical, chemical, thermodynamic and gas-dynamic processes that take place in a weapon from the moment the charge begins to ignite until the end of the outflow of powder gases from the bore of the weapon after the projectile leaves.

The phenomenon of a shot includes the following processes: - ignition of gunpowder; - burning of gunpowder; — formation of powder gases; — cutting the leading belts into the rifling; — forward motion of a bullet (projectile); — friction of the driving belts on the surface of the barrel bore; — rotational movement of a bullet (projectile); — expansion of powder gases; — movement of powder gases; — movement of warhead elements; — change in the composition of powder gases; — heat transfer from powder gases to the walls of the barrel; — barrel heating; — deformation of the barrel, bullet (projectile), cartridge case; - wear and tear of the bore; — displacement of air from the barrel bore; — movement of moving parts of weapon automation; — outflow of powder gases from the barrel; — formation of a muzzle wave; — formation of a muzzle flame.

The listed processes can occur in one or several periods. Thus, the ignition of gunpowder and the cutting of the leading belts into the rifling occurs in the preliminary period, the formation of a muzzle wave - in the aftereffect period. And the movement of powder gases occurs in four periods - preliminary (pyrostatic), pyrodynamic, thermodynamic and aftereffect. The largest number of processes occur simultaneously in the pyrodynamic period, therefore it is the most complex and general.

The listed processes are not equivalent in their role in solving the main problem of pyrodynamics, i.e. from the point of view of revealing the nature of the movement of the projectile in the bore of a gun. The main processes of the shot phenomenon include: - combustion of gunpowder; — formation of powder gases; — expansion of powder gases; — forward motion of the projectile; — outflow of powder gases from the barrel bore.

These processes in internal ballistics are studied in detail.

It should be noted that the combustion of gunpowder occurs first in a constant volume, and from the moment the bullet (projectile) begins to move, in a variable volume; the expansion of powder gases occurs both during the combustion of gunpowder and after its combustion.

During a shot from a small weapon, the following phenomena occur.

Shooting from a 7.62-mm Dragunov SVD-S sniper rifle
When the trigger is released, the firing pin strikes the primer of a live cartridge chambered in the chamber, thereby causing an instant explosion of the percussion composition of the primer. The strong flame that arises in this case penetrates through the seed holes in the bottom of the cartridge case to the powder charge, igniting the grains of gunpowder from all sides. The powder (combat) charge, igniting almost simultaneously, releases a large amount of highly heated elastic powder gases, creating high pressure in the barrel bore on the bottom of the bullet, the bottom and walls of the cartridge case, as well as on the walls of the barrel and the bolt. As the charge burns, the powder gases become crowded in the powder chamber (chamber). Trying to expand, they press in all directions with equal force, including on the bullet. Meeting the resistance of the strong walls of the barrel and the bottom of the cartridge case, which rests against the bolt cylinder, the powder gases spread in the direction of least resistance, pushing the bullet in front of it. As a result of the gas pressure on the bottom of the bullet, it moves from its place and crashes into the rifling; rotating along them, moves along the barrel bore with a continuously increasing speed and is thrown out in the direction of the axis of the barrel bore. The gas pressure on the bottom of the cartridge case causes the weapon (barrel) to move backward. The pressure of the gases on the walls of the cartridge case and barrel causes them to stretch (elastic deformation), and the cartridge case, pressing tightly against the chamber, prevents the breakthrough of powder gases towards the bolt. At the same time, when firing, an oscillatory movement (vibration) of the barrel occurs and it heats up. Hot gases and particles of unburnt gunpowder flowing from the bore after the bullet, when meeting air, form a flame and a shock wave, which is the source of sound when fired.

This is the phenomenon of the shot. It proceeds very quickly. Thus, a bullet in the barrel of a 7.62 mm Mosin repeating rifle of the 1891/30 model. moves for only about 0.0015 seconds.

When fired from an automatic weapon, the design of which is based on the principle of using the energy of powder gases discharged through a hole in the barrel wall (for example, the Kalashnikov AK-74 assault rifle, the Kalashnikov RPK-74 light machine gun; the Dragunov SVD sniper rifle; the single Kalashnikov PKM machine gun), part powder gases, after the bullet passes through the gas outlet hole, rushes through it into the gas chamber, hits the piston and throws the piston with the bolt frame (pusher with the bolt) back.

Until the bolt carrier (bolt stem) travels a certain distance allowing the bullet to exit the barrel, the bolt continues to lock the barrel. After the bullet leaves the barrel, it is unlocked; the bolt frame and bolt, moving backward, compress the return (recoil) spring; the bolt removes the cartridge case from the chamber. When moving forward under the action of a compressed spring, the bolt sends the next cartridge into the chamber and again locks the barrel.

When firing from an automatic weapon, the design of which is based on the principle of using recoil energy (for example, the Makarov PM pistol, the Stechkin APS automatic pistol, the Shpagin submachine gun model 1941 PPSh), the gas pressure through the bottom of the cartridge case is transmitted to the bolt and causes the movement of the bolt with the sleeve back. This movement begins at the moment when the pressure of the powder gases on the bottom of the cartridge case overcomes the inertia of the bolt and the force of the return spring. By this time the bullet is already flying out of the barrel. Moving back, the bolt compresses the recoil spring, then, under the influence of the energy of the compressed spring, the bolt moves forward and sends the next cartridge into the chamber.

In some types of weapons (for example, the Vladimirov KPV heavy machine gun, the Maxim heavy machine gun model 1910), under the influence of the pressure of powder gases on the bottom of the cartridge case, the barrel first moves backward along with the bolt (lock) linked to it. Having passed a certain distance, ensuring that the bullet leaves the barrel, the barrel and the bolt are disengaged, after which the bolt, by inertia, moves to the rearmost position and compresses (stretches) the return spring, and the barrel, under the action of the spring, returns to the forward position.

Firing from a 5.45-mm Kalashnikov AKS-74 assault rifle with a magazine capacity of 60 rounds
The phenomenon of a shot is characterized by short duration and complexity, it lasts tenths and even hundredths of a second (0.001-0.06 sec), and many processes occur in such a short period of time of different nature, connected with each other.

During the shot, high pressures reach thousands of atmospheres and high temperatures up to 3000 °C.

When a powder charge is burned, approximately 25-35% of the released energy is spent on imparting forward motion to the bullet (the main work); 15-25% of energy - for performing secondary work (plunging in and overcoming the friction of a bullet when moving along the bore; heating the walls of the barrel, cartridge case and bullet; moving moving parts of the weapon, gaseous and unburned parts of gunpowder); about 40% of the energy is not used and is lost after the bullet leaves the barrel.

Despite the short duration of the shooting phenomenon, it can be divided into four successive periods.

The preliminary (or pyrostatic) period lasts from the moment the powder charge begins to burn until the bullet shell completely cuts into the rifling of the barrel. During this period, as the gunpowder burns, the amount of powder gases in the bore increases, and therefore the gas pressure necessary to move the bullet (projectile) from its place and overcome the resistance of its shell to cutting into the rifling of the barrel quickly increases. When it reaches a certain value sufficient to overcome the forces of resistance to movement (squeezing the bullet into the barrel of the cartridge case, cutting the bullet into the rifling, etc.), the bullet begins to move. The pressure of the powder gases, which is necessary for the bullet to completely penetrate the rifling, is called boost pressure. In small arms it ranges from 25-50 MPa (250-500 kg/sq.cm) when firing jacketed bullets, depending on the rifling design, the mass of the bullet and the hardness of its shell (for example, in small arms with a 7.62 mm automatic cartridge of the 1943 model, the boost pressure is about 30 MPa (300 kg/sq.cm).

The combustion of the powder charge during this period occurs in a constant volume, the shell (belt) of the bullet (projectile) crashes into the rifling instantly, and its movement begins immediately when the boost pressure is reached in the barrel bore.

Firing from a 7.62-mm single Kalashnikov PKM machine gun
The first (or main) pyrodynamic period lasts from the beginning of the movement of the bullet (projectile) until the moment of complete combustion of the powder charge. During this period, combustion of the powder charge occurs in a rapidly changing volume. At the beginning of the period, when the bullet (projectile) has not yet acquired a high speed of movement along the bore, the amount of gases grows much faster than the volume of the bullet (behind the projectile) space (the space between the bottom of the bullet (projectile) and the bottom of the cartridge case), due to which the gas pressure in the barrel bore it quickly increases and reaches its greatest value. For example, for small arms designed to use a 7.62 mm machine gun cartridge of the 1943 model - 280 MPa (2800 kg/sq. cm), and for a 7.62 mm rifle cartridge - 290 MPa (2900 kg/sq. cm). This pressure is called maximum pressure. It is created in small arms when a bullet travels 4-6 cm (with a 4-10 caliber projectile). Then, due to a significant increase in the speed of the bullet (projectile), the volume of the bullet space increases faster than the influx of new gases, and the pressure in the barrel begins to gradually decrease. At the end of the combustion of gunpowder, the pressure of the powder gases is approximately 2/3 of the maximum pressure. The speed of the bullet constantly increases and by the end of the period reaches approximately 3/4 of the initial speed. The powder charge is completely burned shortly before the bullet leaves the barrel.

The maximum pressure that powder gases develop in the barrel of a 7.62 mm Mosin repeating rifle of the 1891/30 model. when shooting with a light bullet - 285 MPa (2850 kg/sq.cm), when shooting with a heavy bullet - up to 320 MPa (3200 kg/sq.cm). The maximum pressure of powder gases in the 5.6 mm barrel of a small-caliber rifle and pistol is 130 MPa (1300 kg/sq.cm), and in the 7.62 mm barrel of a Nagan revolver of the 1895 model is 110 MPa (1100 kg/sq.cm ).

The second thermodynamic period lasts from the moment of complete combustion of the powder charge until the moment the bullet (projectile) leaves the barrel. With the beginning of this period, the influx of powder gases stops, however, highly compressed and heated gases expand and further movement of the bullet (projectile) occurs under the influence of a constant, freely expanding amount of powder gases, which, due to their elasticity, have an even greater supply of energy; as they continue to expand, they increase the speed of the bullet. The pressure decline in the second period occurs faster than at the end of the first period, and at the muzzle the muzzle pressure (i.e., the pressure of the powder gases at the moment the bullet leaves the barrel) is 1/3 for the gun, and 1 for various types of small arms /5 maximum pressure - from 20 (200 kg/sq.cm to 90 MPa (900 kg/sq.cm). For example, for a 5.6 mm small-caliber rifle TOZ-8 - about 20 MPa (200 kg/sq.cm) ; for a 7.62 mm Mosin repeating rifle model 1891/30 it is 41.6 MPa (416 kg/sq.cm); for a 7.62 mm Simonov SKS self-loading carbine - 39 MPa (390 kg/sq.cm) , for the 7.62 mm Goryunov heavy machine gun - 57 MPa (570 kg/sq.cm).The speed of the bullet at the moment it leaves the barrel (muzzle speed) is slightly less than the initial speed.

The nature of the change in the pressure of powder gases in the barrel bore and the increase in the speed of the bullet when fired from a rifle mod. 1891/30 and small-caliber rifles are shown in Table 1.

Some types of small arms, especially short-barreled ones (for example, the Makarov PM pistol), do not have a second period, since the bullet flies out of the barrel before the powder charge has time to completely burn out.

The third period, or the period of aftereffect of gases, lasts from the moment the bullet (projectile) leaves the barrel until the end of the outflow of powder gases from the barrel and the termination of the action of powder gases on the bullet (projectile). During this period, powder gases, escaping from the barrel at a speed of 1200-2000 m/sec (considerably greater than the speed of the bullet), continue at some distance from the muzzle of the weapon (up to 20 cm) to exert pressure on the bottom of the bullet and impart additional speed - until the resistance of the surrounding air becomes equal to the gas pressure at the bottom of the bullet. Consequently, as the bullet moves through the barrel, its speed continuously increases, reaching its greatest (maximum) at the end of the third period at a distance of several tens of centimeters from the muzzle of the barrel. This period ends at the moment when the pressure of the powder gases at the bottom of the bullet (projectile) is balanced by air resistance.

Firing from a 23-mm twin anti-aircraft gun ZU-23-2
In samples of small arms and artillery weapons, all of the listed periods usually occur, and only in rare cases, when the end of the combustion of gunpowder occurs after the departure of the projectile, is there no thermodynamic period. In mortars, as a rule, there is no boost period.

After passing the muzzle of the weapon, the bullet (projectile) has maximum speed.

It should be noted that the nature of the increase in pressure of powder gases in the barrel bore largely depends on the density of the powder charge. With an increase in charge density, the burning rate of gunpowder sharply increases, and consequently, an increase in gas pressure, up to the occurrence of detonation. Therefore, in order to avoid accidents, you should not shoot cartridges with deep-set bullets.

Sometimes, after the firing pin hits the primer, a shot may not fire or it will follow with some delay. In the first case, a misfire occurs, and in the second, a prolonged shot occurs.

The cause of a misfire is most often dampness of the percussion composition of the primer or powder charge, as well as a weak impact of the firing pin on the primer. As is known, with an increase in the percentage of humidity, gunpowder burns more slowly, which is why the increase in pressure of powder gases in the barrel can also occur more slowly. Therefore, with a damp powder charge, a prolonged shot is possible, in which a noticeable period of time passes between the striker hitting the primer and the sound of the shot. With increased humidity of the charge, as well as insufficient power of the primer, the flame beam from the explosion of the primer composition cannot ignite all the powder grains simultaneously, but only ignites nearby layers of gunpowder, from which the next layers ignite after a certain period of time. In this regard, if after releasing the trigger there is no shot, the shooter should not rush to reload the weapon, but wait a few seconds so that the powder charge cannot explode when the bolt is open and, as a result, injure the shooter and damage the weapon. If a misfire occurs when firing from an SPG-9 easel grenade launcher, then you must wait at least one minute before discharging it.

In this regard, the greatest caution should be exercised when firing cartridges that have been stored for a long time without sealed packaging and in an insufficiently dry place. Therefore, it is necessary to protect ammunition from moisture and keep the weapon in good condition.

Sergey Monetchikov Photo by Vladimir Nikolaychuk and from the author’s archive

Muzzle velocity: influencing factors

For a shooter, the initial velocity of a bullet (projectile) is perhaps the most important of all quantities considered in internal ballistics.

And indeed, the greatest firing range, the range of a direct shot, depends on this value, i.e. the greatest range of direct fire at visible targets, at which the height of the bullet’s flight path does not exceed the height of the target, the time of movement of the bullet (projectile) to the target, the impact effect projectile on target and other indicators.

That is why it is necessary to be attentive to the very concept of initial velocity, to the methods of determining it, to how the initial velocity changes when the parameters of internal ballistics change and when shooting conditions change.

When fired from a small weapon, a bullet begins to move faster and faster along the barrel under the influence of powder gases, reaching its maximum speed a few centimeters from the muzzle. Then, moving by inertia and encountering air resistance, the bullet begins to lose its speed. Consequently, the speed of the bullet changes all the time. Taking this circumstance into account, it is customary to record the speed of a bullet only in certain phases of its movement. Usually the speed of the bullet is recorded as it leaves the barrel.

The speed of the bullet at the muzzle of the barrel at the moment it leaves the barrel is called the initial speed.

The initial speed is taken to be a conditional speed, which is slightly greater than the muzzle and less than the maximum. It is measured by the distance that a bullet could travel in 1 second after leaving the barrel, if neither air resistance nor its gravity acted on it. Since the speed of a bullet at some distance from the muzzle differs little from the speed when it leaves the barrel, in practical calculations it is usually assumed that the bullet has the highest speed at the moment it leaves the barrel, i.e., that the initial speed of the bullet is the highest ( maximum) speed.

The initial speed is determined experimentally with subsequent calculations. The magnitude of the muzzle velocity is indicated in the shooting tables and in the combat characteristics of the weapon.

So, when firing from a 7.62-mm repeating rifle of the Mosin system mod. 1891/30 the initial speed of a light bullet is 865 m/sec, and that of a heavy bullet is 800 m/sec. When firing from a 5.6-mm small-caliber TOZ-8 rifle, the initial bullet speed of various batches of cartridges ranges from 280-350 m/sec.

The magnitude of the initial velocity is one of the most important characteristics not only of cartridges, but also of the combat properties of weapons. However, it is impossible to judge the ballistic properties of a weapon by the initial bullet velocity alone. As the initial speed increases, the bullet's flight range, direct shot range, lethal and penetrating effect of the bullet increases, and the influence of external conditions on its flight decreases.

The magnitude of the muzzle velocity depends on the length of the weapon barrel; bullet mass; mass, temperature and humidity of the cartridge powder charge, shape and size of the powder grains and loading density.

The longer the barrel of a small weapon, the longer the time the bullet is exposed to powder gases and the higher the initial velocity of the bullet.

It is also necessary to consider the muzzle velocity of the bullet in combination with its mass. It is very important to know how much energy a bullet has, what work it can do.

It is known from physics that the energy of a moving body depends on its mass and speed of movement. Therefore, the greater the mass of the bullet and the speed of its movement, the greater the kinetic energy of the bullet. With a constant barrel length and constant mass of the powder charge, the smaller the mass of the bullet, the greater the initial velocity. An increase in the mass of the powder charge leads to an increase in the amount of powder gases, and consequently to an increase in the maximum pressure in the barrel bore and an increase in the initial velocity of the bullet. The greater the mass of the powder charge, the greater the maximum pressure and initial velocity of the bullet.

The length of the barrel and the mass of the powder charge increase when designing small arms to the most rational sizes.

As the temperature of the powder charge increases, the burning rate of the powder increases, and therefore the maximum pressure and muzzle velocity of the bullet increase. As the charge temperature decreases, the initial speed decreases. An increase (decrease) in the initial speed causes an increase (decrease) in the range of the bullet. In this regard, when shooting, it is necessary to take into account range corrections for the temperature of the air and charge (the temperature of the charge is approximately equal to the air temperature).

As the humidity of the powder charge increases, its burning rate and the initial velocity of the bullet decrease.

The shape and size of the gunpowder have a significant impact on the burning rate of the powder charge, and therefore on the initial speed of the bullet. They are selected accordingly when designing weapons.

Loading density is the ratio of the mass of the charge to the volume of the cartridge case with the bullet inserted (charge combustion chamber). When the bullet is seated very deeply, the loading density increases significantly, which can lead to a sharp surge in pressure when fired and, as a result, to rupture of the barrel, so such cartridges cannot be used for shooting. As the loading density decreases (increases), the initial bullet speed increases (decreases).

The penetrating effect of a bullet (Tables 1 and 2) is characterized by its kinetic energy (living force). The kinetic energy imparted to the bullet by the powder gases at the moment it leaves the barrel is called muzzle energy. Bullet energy is measured in joules.

Rifle bullets have enormous kinetic energy. Thus, the muzzle energy of a light bullet when fired from a rifle of the 1891/30 model. equal to 3600 J. How great the energy of a bullet is can be seen from the following: to obtain such energy in such a short period of time (not by shooting), a machine with a power of 3000 hp would be required. With.

From all that has been said, it is clear what great practical significance a high initial velocity and the muzzle energy of a bullet, which depends on it, have for shooting. With an increase in the initial speed of the bullet and its muzzle energy, the firing range increases; the bullet trajectory becomes more sloping; the influence of external conditions on the flight of a bullet is significantly reduced; the bullet's penetration effect increases.

At the same time, the magnitude of the initial velocity of the bullet (projectile) is greatly influenced by the wear of the barrel bore. During operation, the barrel of a weapon is subject to significant wear. This is facilitated by a number of reasons of a mechanical, thermal, gas-dynamic and chemical nature.

First of all, when a bullet passes through the bore, due to high friction forces, it rounds the corners of the rifling fields and abrades the inner walls of the bore. In addition, particles of powder gases moving at high speed strike with force the walls of the barrel bore, causing so-called hardening on their surface. This phenomenon consists in the fact that the surface of the bore is covered with a thin crust with fragility gradually developing in it. The elastic deformation of the barrel expansion that occurs during a shot leads to the appearance of small cracks on the inner surface of the metal. The formation of such cracks is also facilitated by the high temperature of the powder gases, which, due to their very short action, cause partial melting of the surface of the barrel bore. Large stresses arise in the heated layer of metal, which ultimately lead to the appearance and enlargement of these small cracks. The increased fragility of the surface layer of the metal and the presence of cracks on it lead to the fact that the bullet, when passing through the bore, produces metal chips in places of cracks. The wear of the barrel is greatly contributed to by the soot remaining in the bore after the shot. It represents the remains of combustion of the primer composition and gunpowder, as well as metal scraped from the bullet or melted from it, pieces of the cartridge case torn off by gases, etc.

The salts present in soot have the property of absorbing moisture from the air, dissolving in it and forming solutions, which, when reacting with the metal, lead to its corrosion (rusting), the appearance of first a rash and then cavities in the barrel bore. All these factors lead to changes and destruction of the surface of the barrel bore, which entails an increase in its caliber, especially at the bullet entrance, and, naturally, a decrease in its overall strength. Therefore, the noted change in parameters when the barrel wears leads to a decrease in the initial speed of the bullet (projectile), as well as to a sharp deterioration in the weapon’s combat, i.e., to the loss of its ballistic qualities.

If in the time of Peter I the initial flight speed of the cannonball reached 200 meters per second, then modern artillery shells fly much faster. The flight speed of a modern projectile in the first second is usually 800-900 meters, and some projectiles fly even faster - at a speed of 1000 or more meters per second. This speed is so high that the projectile, when it flies, is not even visible. Consequently, a modern projectile travels at a speed 40 times the speed of a courier train and 8 times the speed of an airplane.

However, here we are talking about ordinary passenger aircraft and artillery shells flying at average speed.

If we take for comparison, on the one hand, the “slowest” projectile, and on the other, a modern jet aircraft, then the difference will not be so great, and not in favor of the projectile: jet aircraft fly at an average speed of about 900 kilometers per hour , that is, about 250 meters per second, and a very “slow” projectile, for example, a projectile from the 152-mm Msta 2 S19 self-propelled howitzer, with the smallest charge, flies only 238 meters in the first second.

It turns out that the jet aircraft will not only keep up with such a projectile, but will also outrun it.

A passenger plane flies about 900 kilometers in an hour. How far will a projectile flying several times faster than an airplane fly in an hour? It would seem that the projectile should fly about 4,000 kilometers in an hour.

In fact, however, the entire flight of an artillery shell usually lasts less than a minute, the shell flies 15-20 kilometers and only for some guns more.

What's the matter? What prevents a projectile from flying as long and as far as an airplane flies?

The plane flies for a long time because the propeller pulls or the jet engine pushes it forward all the time. The engine runs for several hours in a row until there is enough fuel. Therefore, the plane can fly continuously for several hours in a row.

The projectile receives a push in the gun channel, and then flies on its own, no force anymore pushes it forward. From a mechanical point of view, a flying projectile will be a body moving by inertia. Such a body, mechanics teaches, must obey a very simple law: it must move rectilinearly and uniformly, unless no other force is applied to it.

Does the projectile obey this law, does it move in a straight line?

Let's imagine that a kilometer away from us there is a target, for example, an enemy machine-gun point. Let's try to aim the gun so that its barrel is pointed directly at the machine gun, then we'll fire a shot.

No matter how many times we shoot like this, we will never hit the target: each time the shell will fall to the ground and explode, having flown only 200-300 meters. If we continue our experiments, we will soon come to the following conclusion: in order to hit, we need to point the barrel not at the target, but slightly above it.

It turns out that the projectile does not fly forward in a straight line: it descends in flight. What's the matter? Why does the projectile not fly straight? What force pulls the projectile down?

Artillery scientists of the late 16th and early 17th centuries explained this phenomenon this way: a projectile flying obliquely upward loses strength, like a man climbing a steep mountain. And when the projectile finally loses its power, it will stop for a moment in the air, and then fall down like a stone. The path of a projectile in the air seemed to artillerymen of the 16th century to be as shown in the figure.

Nowadays, all people who have studied physics, knowing the laws discovered by Galileo and Newton, will give a more correct answer: the force of gravity acts on a flying projectile and causes it to fall during its flight. After all, everyone knows that a thrown stone does not fly straight, but describes a curve and, having flown a short distance, falls to the ground. All other things being equal, the stone flies farther, the harder it is thrown, the greater the speed it received at the moment of the throw.

Let's put a weapon in the place of the person throwing the stone, and replace the stone with a projectile; like any flying body, the projectile will be attracted to the ground during flight and, therefore, will move away from the line along which it was thrown; in artillery this line is called the throwing line, and the angle between this line and the horizon of the gun is the throwing angle.

If we assume that the projectile is only affected by gravity during its flight, then under the influence of this force in the first second of flight the projectile will drop approximately 5 meters (more precisely, 4.9 meters), in the second - almost 15 meters (more precisely, by 14.7 meters) and in each subsequent second the falling speed will increase by almost 10 meters per second (more precisely, by 9.8 meters per second). This is the law of free fall of bodies discovered by Galileo.

That’s why the projectile’s flight line—the trajectory—is not straight, but exactly the same as for a thrown stone, similar to an arc.

In addition, one may wonder: is there a connection between the throwing angle and the distance that the projectile flies?

Let's try to fire the gun once with the barrel in a horizontal position, another time with the barrel at a throwing angle of 3 degrees, and a third time with a throwing angle of 6 degrees.

In the first second of flight, the projectile must move down 5 meters from the throwing line. This means that if the gun barrel lies on a machine 1 meter high from the ground and is directed horizontally, then the projectile will have nowhere to go down and will hit the ground before the first second of flight has elapsed. Calculations show that within 6 tenths of a second the projectile will hit the ground.

A projectile thrown at a speed of 600-700 meters per second, with the barrel in a horizontal position, will fly only 300 meters before falling to the ground. Now let's fire a shot at a throwing angle of 3 degrees.

The throwing line will no longer go horizontally, but at an angle of 3 degrees to the horizon.

According to our calculations, a projectile fired at a speed of 600 meters per second should have risen to a height of 30 meters in a second, but gravity will take away 5 meters of rise from it, and in fact the projectile will be at a height of 25 meters above the ground. After 2 seconds, the projectile, if there were no gravity, would have risen to a height of 60 meters, but in fact, gravity will take away another 15 meters in the second second of flight, but only 20 meters. By the end of the second second, the projectile will be at a height of 40 meters. If we continue the calculations, they will show that already at the fourth second the projectile will not only stop rising, but will begin to fall lower and lower. And by the end of the sixth second, having flown 3600 meters, the projectile will fall to the ground.

The calculations for a shot at a throwing angle of 6 degrees are similar to those we just did, but the calculations will take much longer: the projectile will fly for 12 seconds and fly 7200 meters.

Thus, we realized that the greater the throwing angle, the further the projectile flies. But there is a limit to this increase in range: the projectile flies the furthest if it is thrown at an angle of 45 degrees. If you further increase the throwing angle, the projectile will climb higher and higher, but it will fall closer and closer.

It goes without saying that the flight range will depend not only on the throwing angle, but also on the speed: the greater the initial speed of the projectile, the further it will fall, all other things being equal.

For example, if you throw a projectile at an angle of 6 degrees with a speed of not 600, but 170 meters per second, then it will fly not 7200 meters, but only 570.

Consequently, the actual maximum initial velocity of a projectile, which can be achieved in a classic artillery gun, fundamentally cannot exceed the value of 2500-3000 m/s, and the actual firing range does not exceed several tens of kilometers. This is the peculiarity of artillery barrel systems (including small arms), realizing which humanity, in the quest for cosmic speeds and ranges, turned to the use of the reactive principle of propulsion.

Sergey Monetchikov Photo by Vladimir Nikolaychuk and from the author’s archive

The phenomenon of a shot, its periods and their characteristics

Ballistics - (Greek ballos - throw, throw) - the science that studies the laws of motion of a bullet (shell, mine, etc.).

Ballistics consists of two main parts:

Internal ballistics is a science that studies the processes that occur during a shot and especially when a bullet (grenade) moves along the barrel under the influence of powder gas pressure.

External ballistics is a science that studies the movement of a bullet (grenade) after the action of powder gases on it ceases, i.e. movement of a bullet (grenade) in the air.

Along with this, there are the concepts of intermediate ballistics and target ballistics.

Intermediate ballistics - considers the movement of a bullet at a certain distance after leaving the barrel (for small arms from 30 to 150 cm), where gases continue to affect the flight of the bullet.

Target ballistics - studies the movement of projectiles in the environment (targets, obstacles), which is especially important for calculating armor penetration and destruction of fortifications.

In small arms and artillery, ballistics is of an applied nature and is studied with the aim of:

— theoretical justification for the design of the material part of the weapon;

- theoretical justification for shooting and rules for saving, storing and inspecting weapons, which is directly included in the task of fire training classes.

Internal ballistics studies the most rational use of the energy of a powder charge during a shot.

The solution to this issue is the main task of internal ballistics: how to impart a certain initial velocity (V0) to a projectile of a given weight and caliber, provided that the maximum gas pressure in the barrel (Pm) does not exceed a given value.

For a shot to occur, the weapon must be loaded. Necessary elements for a shot: primer, charge and bullet.

When the trigger is pulled, the firing pin breaks the primer. The percussion composition of the primer instantly explodes and its flame penetrates through the seed holes in the bottom of the cartridge case to the charge and engulfs the grains of gunpowder; the entire charge of gunpowder ignites almost simultaneously and burns, turning into gases with very high pressure; under the influence of gas pressure, the bullet begins to move, crashes into the rifling and rotates along them, moves along the barrel bore with a continuously increasing speed and is thrown outward in the direction of the axis of the barrel bore. A shot occurs.

A shot is the ejection of a bullet (shell, grenade) from the bore of a weapon by the energy of powder gases formed during the combustion of a powder charge.

In ballistics, a shot is considered as a process of very rapid transformation of the chemical energy of gunpowder, first into thermal, and then into the kinetic energy of the weapon’s movement (a weapon is understood as a charge-projectile-barrel system).

The shot is characterized by:

— Development of high pressure of powder gases (Pm) in the barrel bore. For example, the powder charge of a cartridge mod. 1943 weighing 1.6 g gives 1.6 liters in an explosion. gases, i.e. approximately 1000 times more in volume than there was an explosive before the explosion. Due to this, the pressure (Pm) in the barrel bore during firing reaches 2500-3500 kg/cm². The same charge weighing 1.6 g pushes a bullet weighing 7.9 g out of the bore of the machine gun at a speed of 715 m/sec (2680 km/h) and throws it at a distance of up to 3000 m.

To convey such a speed to a bullet, you need to expend a force equal to 225 kg/m. If you multiply 225 kg/m by 2680, and then convert this value into horsepower, it turns out that the shot power is 2100 hp, i.e. at 100 hp more power of the locomotive. However, the locomotive has its 2000 hp. gives off continuously, second after second, hour after hour, and the weapon develops its power in small fractions of a second.

- Release of a large amount of heat. The gas temperature reaches 2500-3500 C°, which is twice the melting point of steel. For example, during the explosion of 1 kg of explosive, from 500 to 1200 large calories of heat are released.

- Short duration of the phenomenon (0.0012-0.06 sec).

For example, the powder charge of a cartridge mod. 1943 burns out when fired in 0.0012 seconds, a demolition stick of dynamite - in about 0.00001 seconds.

- Strong sound.

— A flame arising from the mixing of hot gases with oxygen in the air.

Sometimes, due to breakage or wear of the firing pin, deep seating of the primer in the socket of the case bottom, or dampening of the primer composition, a misfire occurs.

Practical conclusions:

— Since the firing phenomenon is accompanied by a very high gas pressure in the barrel, it is necessary to carefully check the serviceability and cleanliness of the barrel and especially the bolt before shooting. Never close the barrel from the muzzle (in order to protect the barrel from rain or snow), because a shot with a foreign object in the barrel (Fig. 1) gives a sharp jump in gas pressure, which can lead to swelling or even rupture of the barrel;

Rice. 1 Causes of swelling of the trunk.

— High temperatures and pressure of gases during a shot create high stresses in the metal of the barrel. The barrel is designed for a certain firing mode, which cannot be exceeded. For example, continuous fire from a machine gun or machine gun should be carried out only in combat conditions, avoiding overheating of the barrel;

— Thus, timely and proper cleaning of weapons and removal of soot containing harmful combustion products of gunpowder, which have a great impact on barrel wear, is an effective measure to ensure the safety of the combat properties of the weapon.

An essential feature of the shot is that the main work of the powder gases to push the projectile occurs in a variable volume.

All these features complicate the study of the shooting phenomenon, and in order to get the overall picture it is necessary to examine it in parts. Internal ballistics divides the phenomenon of a shot into four periods:

— preliminary

- first (main)

- second

- third (period of gas effects)

Consider these periods:

From the impact of the striker, the percussion composition of the primer ignites, the resulting gases, creating an initial pressure of about 20-40 kg/cm², ignite the powder charge.

During the combustion of a powder charge, a large amount of highly heated gases are formed, which spread in all directions and, trying to expand, put pressure on the bottom of the cartridge case, on its walls and on the bullet. When the pressure force reaches a value greater than the resistance force of the bullet (inertia, compression of the bullet in the case and increased penetration of the bullet into the rifling), the bullet begins to move forward, crashing into the rifling.

The period of the shot phenomenon from the moment the combat charge is ignited until the bullet (projectile) is completely embedded in the rifling of the barrel is called the preliminary period.

Rice. 2 Shot phenomenon

During this period, the combustion of gunpowder occurs in a constant volume until the pressure reaches the value necessary for cutting the bullet (projectile) into the rifling.

The gas pressure required to completely insert a bullet into the rifling of the barrel is called boost pressure (Pf). It is necessary to move the bullet (projectile) from its place and overcome the resistance of the leading belt of the projectile (bullet shell) to cutting into the rifling of the barrel.

The boost pressure ranges from 250-500 kg/cm².

The first (main) period of a shot is the period from the beginning of the movement of the bullet (projectile) until the end of the combustion of the combat charge.

During this period, the combustion of gunpowder occurs in a rapidly changing volume, because The projectile, under the pressure of a continuously increasing amount of gases, moves along the bore. In the first period of time, the increase in the amount of gases is much faster than the increase in the volume of the pulverized space, so the pressure quickly increases, reaching its greatest value, maximum (PM).

The highest pressure achieved by gases in the bore is called maximum pressure. The maximum pressure for small arms ranges from 2000 to 3500 kg/cm².

Subsequently, due to a significant increase in bullet speed and bullet volume, the pressure drops. At the end of gunpowder combustion, the pressure Pk is approximately 2/3 of the maximum (Pk ≈ 2/3 Pm). The velocity at this moment is approximately 1/4 muzzle velocity.

The second period of the shot is called the period from the moment the combustion of the gunpowder of the combat charge ends until the moment the bullet leaves the bore of the weapon.

With increasing gas pressure, the speed of the bullet increases, which is why the volume of the bullet space quickly increases. When the volume of the pool space grows faster than the formation (influx) of gases, the pressure begins to fall (decrease). The gas pressure reaches its greatest value when the bullet is 4-6 cm from the beginning of the rifled part of the barrel. At this point, the pressure of the powder gases reaches 2800-2900 atmospheres (2800-2900 kg/cm²). Then, due to an increase in the speed of movement, the volume of the behind-the-pulse space increases faster than the influx of new gases, and the pressure begins to fall. By the time the bullet leaves the barrel, it reaches 300-900 kg/cm².

However, simultaneously with the drop in pressure, the speed of the bullet does not decrease, but increases. This is explained by the fact that the gases continue to press on the bullet, which received acceleration during the period of greatest pressure, although to a lesser extent, and thereby accelerate its movement.

The force of gas pressure is quite sufficient for the bullet to continuously receive acceleration and be thrown out of the barrel with greater speed. The pressure drop occurs faster than at the end of the first period. The muzzle pressure of small arms chambered for a 7.62 mm rifle cartridge is 1/5 of the maximum pressure (Рд ≈ 1/5 Рm). The pressure of gases at the moment a bullet (projectile) leaves the barrel is called muzzle pressure. For small arms it is 400-600 kg/cm². For short-barreled weapons, for example, the 9 mm Makarov pistol, the second period is practically absent, because the bullet leaves the weapon before the entire powder charge burns out.

The third period or the period of aftereffect of gases is the period of the shot from the moment the projectile takes off until the moment the action of the flowing powder gases on it ceases.

This period of the shot is characterized by the fact that gases flowing from the barrel at a speed of 1200-2000 m/sec or more continue to influence the projectile until their force is balanced by the force of air resistance acting on the projectile.

During this period, under the influence of gases, the projectile continues to accelerate over an area of ​​5-10 m, and the bullet over an area of ​​several tens of centimeters.

After passing through the muzzle of the weapon, the projectile has a muzzle velocity Vо, and at the end of the aftereffect it has a maximum velocity.

The shooting and performance characteristics tables give the value of the initial speed.

Thus, the pressure of the powder gases in the barrel first increases almost instantly to the value Рф, then Рф continues to increase sharply to Рmax, after which it begins to drop to Рд at the moment the bullet leaves the barrel and a further drop occurs during the aftereffect of the gases. The bullet speed continuously increases, first faster and then slower, reaching the value Vmax.

Date added: 2015-09-12;
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FOR THE OPERATION OF AUTOMATIC WEAPONS

T E M A No. 1

SMALL ARMS SHOOTING BASICS

BRIEF INFORMATION FROM INTERNAL BALLISTICS.

A shot is the ejection of a bullet from the bore of a weapon by the energy of gases formed during the combustion of a powder charge.

When a small weapon is fired, the following phenomena occur. When the firing pin strikes the primer of a live cartridge sent into the chamber, the percussion composition of the primer explodes and a flame is formed, which penetrates through the seed holes in the bottom of the cartridge case to the powder charge and ignites it. When a powder (combat) charge burns, a large amount of highly heated gases are formed, creating high pressure in the barrel bore on the bottom of the bullet, the bottom and walls of the cartridge case, as well as on the walls of the barrel and the bolt.

When a powder charge is burned, approximately 25–35% of the released energy is spent on imparting forward motion to the bullet (the main work); 15 - 25% of energy - for performing secondary work (plunging in and overcoming the friction of the bullet when moving along the bore; heating the walls of the barrel, cartridge case and bullet, moving the moving parts of the weapon, gaseous and non-combustible parts of gunpowder); about 40% of the energy is not used and is lost after the bullet leaves the barrel. The shot occurs in a very short period of time (0.001 - 0.06 seconds). When firing, four successive periods are distinguished: preliminary, first (or main), second, third (or gas aftereffect period).

PRELIMINARY PERIOD - lasts from the beginning of combustion of the powder charge until the bullet casing is completely embedded in the rifling of the barrel. During this period, gas pressure is created in the barrel bore, which is necessary to move the bullet from its place and overcome the resistance of its shell to cut into the rifling of the barrel. This pressure is called boost pressure , it reaches 250-500 kg/cm2. It is assumed that the combustion of the powder charge in this period occurs in a constant volume.

FIRST OR MAIN PERIOD - lasts from the beginning of the bullet’s movement until the moment of complete combustion of the powder charge. During this period, combustion of the powder charge occurs in a rapidly changing volume. The gas pressure quickly increases and reaches its highest value (2800 kg/cm2 - 2900 kg/cm2). This pressure is called maximum pressure. It is created in small arms when a bullet travels 4–6 cm. The speed of the bullet constantly increases and at the end of the period reaches approximately ¾ of the initial speed, the powder charge completely burns out shortly before the bullet leaves the barrel.

SECOND PERIOD - lasts from the moment of complete combustion of the powder charge until the moment the bullet leaves the barrel. With the beginning of this period, the influx of powder gases stops, however, highly compressed and heated gases expand, increasing the speed of the bullet. The pressure drop occurs quite quickly, and at the muzzle the muzzle pressure is 300 - 900 kg/cm2 for various types of weapons. The speed of the bullet at the moment it leaves the barrel (muzzle speed) is slightly less than the initial speed.

The Makarov pistol does not have a second period, since complete combustion of the powder charge does not actually occur by the time the bullet leaves the barrel.

THIRD PERIOD - or the period of gas effects, lasts from the moment the bullet leaves the barrel until the moment the action of powder gases on the bullet ceases. Gases flowing from the barrel at a speed of 1200-2000 m/s continue to affect the bullet and impart additional speed to it. The bullet reaches its highest (maximum) speed at the end of the third period at a distance of several tens of centimeters from the muzzle of the barrel.

INITIAL SPEED AND ENERGY OF THE BULLET.

The initial speed of a bullet is the speed of the bullet at the muzzle of the barrel. The initial speed is taken to be a conditional speed, which is slightly greater than the muzzle and less than the maximum.

The initial speed of a bullet is measured in m/s. For example, the initial flight speed of a PM bullet is 315 m/s, and a Kalashnikov assault rifle is 715 m/s. The magnitude of the initial velocity of a bullet is one of the most important characteristics of the combat properties of a weapon and is indicated in the shooting tables. For the same bullet, an increase in channel speed leads to an increase in flight range, direct shot range, penetrating and lethal action of the bullet, as well as a decrease in the influence of external conditions on its flight.

WEAPON RECOIL:

Recoil is the backward movement of a weapon during a shot. Recoil is felt in the form of a push to the shoulder, arm or ground. The recoil speed of a weapon is approximately the same number of times less than the initial speed of a bullet, how many times the bullet is lighter than the weapon.

The recoil energy of hand-held small arms usually does not exceed 2 kg/m and is perceived painlessly by the shooter.

USING THE ENERGY OF POWDER GASES

FOR THE OPERATION OF AUTOMATIC WEAPONS

When firing from an automatic weapon, the design of which is based on the principle of using recoil energy, part of it is spent on imparting movement to moving parts and on reloading the weapon. Therefore, the recoil energy when fired from such a weapon is less than when fired from a non-automatic weapon or from an automatic weapon, the design of which is based on the principle of using the energy of powder gases discharged through a hole in the barrel wall.