- April 4, 2020
- Weapons and ammunition
- Tamila Gresko
Judging by numerous reviews, hunters most often prefer the domestic MP-155 rifle for its reliability, which is very important in the harsh Russian taiga. However, this rifle unit is valuable not only because of its reliable system. Many people like it for its impressive appearance. Be that as it may, a hunting rifle should be looked after, namely, cleaned and lubricated in a timely manner, and for this it must first be disassembled. You will learn more about disassembling the MP-155 from this article.
Replaces MP-153. Part I
This article about the MP-155 self-loading is the first material that claims to be somewhat complete regarding both the history of the development of the gun and its design and operational features. The information content of the publication is unique. Warning against the statements of critics of everything domestic, I want to immediately mention that this article was written with the direct participation of the MP-155 developers and the author has personal experience in operating the gun, confirmed by the general opinion of the owners of the new “Murka”, of which there are more and more.
MP-155. History of appearance and design features
— the “balance” parameter (the distance from the trigger to the center of mass of the gun), which affects the ease of holding and turning ability of the gun, is large in the MP-153 compared to its competitors;
— there were few additional options, for example, there was no possibility of adjusting the butt retraction vertically and horizontally, along the length, and in the basic configuration there was no seat for installing optics or an adapter bar for it;
Appearance of MP-153 and MP-155
Based on the situation, it was decided to create a new model of a self-loading rifle. In December 2010, an order was issued to develop a new product, and work began. The development and development work was supervised by Chief Designer Alexander Usherovich Dorf.
But work on a new self-loading rifle did not begin immediately. A number of experimental works were previously carried out, during which various design solutions were tested and studied. For example, samples with different types of locking were developed and tested: with a rotating bolt, various options with a skewed locking element - a wedge. Various designs of gas engine pulse control units were tested. All this work was carried out at a time when the position of the MP-153 gun on the market was still quite stable. By the way, it should be noted that such research work in all areas of products to find and evaluate new solutions is constantly being carried out at the enterprise. As a result, at the time the work began, the layout and structural solution of the main components had already been determined.
Appearance of MP-153 and MP-155
It was necessary not only to create a new and more modern product, but also not to lose the advantages of the MP-153, namely:
A new firing mechanism was developed. Compared to the MP-153, there are fewer parts in it, and the USM base is made of high-strength polyamide. Many people express doubts about the use of polymer for such a critical part, but polyamide with similar properties is used to make magazines for the Kalashnikov assault rifle, and they do not raise any doubts about the reliability and durability of anyone.
Initially, a unique technology was developed for attaching the strap to the barrel using the welding method: studs were attached to the barrel by contact welding, holes were drilled in the strap, the strap was installed with holes on the studs and welded. The first batch was produced with this type of plank fastening. But due to the difficulties encountered when debugging the technical process, they switched to a more traditional soldering technology using silver-containing solder. But there were difficulties here too. The high temperature of soldering with this solder causes deformation of parts and the appearance of marks in the barrel bore at the soldering points.
About complete disassembly of the gun
It is started after partial disassembly of the MP-155. Unscrew the fixing screws and separate the stock with the butt plate-shock absorber. Now you can begin disassembling the firing mechanism. To do this, first cock the hammer so that the sear engages. Then carefully release the trigger. At this stage, hold it with your finger. When you knock out the axis of the hammer, trigger and sear using a drift, disconnect the hammer from the mainspring, pusher, sear and disconnector. Then you can begin to remove the fuse. You need to press on it, take out the spring and the pressure.
Design Features
The MP-155 automation is driven by a side-mounted gas engine. The unit for regulating the pressure of powder gases in the engine, which ensures reliable operation of the gun with a wide range of ammunition, is located in the piston. Moving the adjustment unit from the barrel post (as was the case in its predecessor) to the piston made it possible to reduce the weight of the barrel, while the weight of the piston remained the same. Here it must be clarified that in the MP-153 the piston was made massive in order to ensure a good supply of kinetic energy in the moving parts. This is necessary for trouble-free operation in difficult conditions (dirt, frost, ice).
The piston has an adjusting nut that tightens the valve spring. The valve spring presses on the valve, which, when a certain gas pressure is reached, moves, compressing the valve spring, and releases some of the gases from the engine into the atmosphere. It is technologically difficult and expensive to produce valve springs that are exactly the same, so their parameters may differ slightly. Depending on the performance of the spring, they are marked in different colors. When assembling the piston in accordance with the color marking, rotating the adjusting nut achieves the same spring preload force. After running in the gun, which takes 100-200 shots, it is recommended to unscrew the nut 1-2 turns (to loosen the spring preload and thereby reduce the rollback speed of the moving parts).
The receiver is made of high-strength aircraft grade B95 aluminum. Analogues of this material are used by most manufacturers in the world. There are grooves on the top of the box for installing optics or adapter strips. Initially, these were two pairs of grooves, one on one with the one in some versions of the MP-153. But later, to increase versatility and simplify the selection of a bracket or optics, a flat was introduced on the top of the box, this made it possible to reduce the required height of the bracket supports, and the separate grooves were combined into single ones.
The forend of the new gun has also undergone transformations. It became conical in shape, tapering towards the muzzle. Now, in the hand-grip area, the fore-end has a thin cross-section, which makes it easier to hold. And to ensure strength, the fore-end thickens toward the rear.
The gun can be made for left-handed shooters. Its difference: the operating order of the safety is reversed, the butt release is on the left, the window for ejecting the cartridge case and the handle are also located on the left.
Currently, development of a pistol grip and a new folding stock are underway. The folding stock used on the MP-153 was reliable and functional, using elements from the AK-74M. But for a smooth-bore gun, with significantly greater recoil than on a machine gun, it turned out to be not very convenient. It is planned that the new stock will become more convenient and suitable for use in a left-handed version.
Work is also underway to create a modification of the gun for practical shooting. It turned out that the enlarged holder button, more convenient for hunter shooters, does not suit sports shooters at all: when quickly loading the button, you can accidentally press the button, which will cause a hitch and loss of time in the exercise. These and other requirements will be taken into account in the new modification.
Gas engine
The unit is greatly modified compared to the MP-153. The main difference is the transfer of the gas release system from the barrel to the piston. Theoretically, this is absolutely correct; the mass of metal begins to work much more optimally. I think it also makes cleaning the unit much easier, as well as replacing it if necessary, as well as making adjustments, although the latter requires additional checking. As well as the need for any adjustment in principle.
Some doubt is raised by the reduction in the area of soldering of the gas chamber to the barrel - for example, I encountered a chamber breakage along the soldering at Fabarm twice, and, as I remember, there were problems with this at the beginning of the production of the MP-133, on which, compared to the Izh-81, the length " legs" of the front ring has sharply decreased.
By the way, the need for adjustment was later confirmed. There are separate complaints about non-reloading of sporting cartridges with a 28 g load. As on the MP-153, on many of them there was rubbing of the piston against the wall of the gas chamber, which was usually eliminated by turning the valve nut in one direction or another by a quarter or even half a turn. There is no such nut on the MP-155.
I must say that I had to shoot from some Turkish guns that did not have any adjustment at all, loading mixed cartridges with 24 and 50 g - and no problems, everything worked. Although, of course, for this, more powder gases must be taken from the barrel, and with some types of powders (fortunately, not for all), the muzzle velocity of the shot can noticeably decrease. And when firing magnum cartridges, an increased shock load from the bolt to the box appears, which is also not good. Well, “everyone has their own shortcomings.”
The choke tubes and magazine nut remain the same. The 153 handguard fits 155 like it was originally, the reverse focus was unsuccessful. The interchangeability of the butts remains to be determined; according to estimates, they should fit both ways.
Summary
Surely the reader, especially the potential owner of the MP-155, will have a question about the comparative characteristics of the “murka”. If you try to compare the MP-155 with its main Western-made competitors, you get the following. Shotguns from Italian manufacturers, who today are called trendsetters in gun fashion, have excellent ergonomics, excellent performance characteristics, and a high level of finishing. This is the result of an advanced design school, the most advanced technologies, and the powerful economy of weapons companies (which did not have a devastating period like our “troubled 90s”). When compared with Italian shotguns, the MP-155 is inferior primarily in the level of finishing and quality of surface treatment.
Of course, time and the market will show who is better and what best meets the needs of customers. But the new domestic “Murka” has every chance of becoming as popular a gun as the previous MP-153 model.
Top comments by rating
I would also like to quote a few statements from this article:
“By the way, it should be noted that such research work in all areas of products to find and evaluate new solutions is constantly being carried out at the enterprise. As a result, at the time of the start of work, the layout and structural solution of the main components had already been determined.”
“There are grooves on the top of the box for installing optics or adapter strips.”
Why optics on smooth ones? ok, still a collimator, but optics!! Although if you declare a confident bullet fight at a distance of 100m for a given barrel, then it is possible. but funny.
“The gun turned out to be light, comfortable, with an original and recognizable design.”
“Work is also underway to create a modification of the gun for practical shooting. It turned out that the enlarged holder button, more convenient for hunter shooters, does not suit sports shooters at all: when quickly loading the button, you can accidentally press the button, which will cause a hitch and loss of time in the exercise. These and other requirements will be taken into account in the new modification.”
“When creating a new gun, it was not possible to avoid some childhood illnesses, but work to eliminate shortcomings and improve the model is carried out constantly and promptly.”
Something is invisible. Both the first-release guns and the new ones look the same, and are visually the same. I believe that such work should be carried out based on the opinions of end users.
The undeniable advantage of any gun is reliability, reliability and durability, ensured by a proven design and high-quality materials. Or do you want to say that the quality data of other guns on the market (including Turkish ones) are lower than those of the MR? I think at the moment the MP155 is playing in terms of these parameters to all competitors on the market, at least in points provided with a proven design and high-quality materials for sure.
There are chances, as long as the dollar is expensive and sanctions (the Turks and the hedgehogs have grown in price with them). But we understand that this will not last forever. Prices will come to an optimum and then the MP155 will clearly gather dust on store shelves.
Now my assessments as a failed user of this gun. Cons: 1. Poor balance in the 750mm barrel. 2. Clumsy design. 3. Poor and inconsistent workmanship. 4. The presence of unnecessary design features (cut-off). 5. Inconvenient plastic stock and butt. 6. Not worth the money. Pros: 1. Possibility to buy spare parts (although there is no particular abundance yet, such as on the MP153). That's all.
I would also like to quote a few statements from this article:
“By the way, it should be noted that such research work in all areas of products to find and evaluate new solutions is constantly being carried out at the enterprise. As a result, at the time of the start of work, the layout and structural solution of the main components had already been determined.”
“There are grooves on the top of the box for installing optics or adapter strips.”
Why optics on smooth ones? ok, still a collimator, but optics!! Although if you declare a confident bullet fight at a distance of 100m for a given barrel, then it is possible. but funny.
“The gun turned out to be light, comfortable, with an original and recognizable design.”
“Work is also underway to create a modification of the gun for practical shooting. It turned out that the enlarged holder button, more convenient for hunter shooters, does not suit sports shooters at all: when quickly loading the button, you can accidentally press the button, which will cause a hitch and loss of time in the exercise. These and other requirements will be taken into account in the new modification.”
“When creating a new gun, it was not possible to avoid some childhood illnesses, but work to eliminate shortcomings and improve the model is carried out constantly and promptly.”
Something is invisible. Both the first-release guns and the new ones look the same, and are visually the same. I believe that such work should be carried out based on the opinions of end users.
The undeniable advantage of any gun is reliability, reliability and durability, ensured by a proven design and high-quality materials. Or do you want to say that the quality data of other guns on the market (including Turkish ones) are lower than those of the MR? I think at the moment the MP155 is playing in terms of these parameters to all competitors on the market, at least in points provided with a proven design and high-quality materials for sure.
There are chances, as long as the dollar is expensive and sanctions (the Turks and the hedgehogs have grown in price with them). But we understand that this will not last forever. Prices will come to an optimum and then the MP155 will clearly gather dust on store shelves.
Now my assessments as a failed user of this gun. Cons: 1. Poor balance in the 750mm barrel. 2. Clumsy design. 3. Poor and inconsistent workmanship. 4. The presence of unnecessary design features (cut-off). 5. Inconvenient plastic stock and butt. 6. Not worth the money. Pros: 1. Possibility to buy spare parts (although there is no particular abundance yet, such as on the MP153). That's all.
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Subtleties of operation of MP-155
Although, perhaps, something will not become new. This article aims to convey to beginners who are just looking at their first gun as much practical information as possible about this model. Perhaps one of the owners will learn something new for themselves. Today we will talk about disassembling and assembling this gun. We will describe the subtleties and pitfalls that may affect the owner.
Final stage
At this stage, the weapon mechanism is removed from the bolt. Knock up the striker pin, and then remove it along with the striker, spring and washer. When you remove the extractor, hold its tension, as its spring may jump out. In some shooting units, it is technically impossible to remove the feeder. The magazine tube in such a gun is equipped with a special groove, thanks to which the magazine capacity does not exceed two rounds of ammunition. If there is no such groove and you want to dismantle the feeder, then press the protrusions in the plastic cup, and press the cup itself into the tube and turn it around the axis. To prevent it from flying out under the influence of the magazine spring, hold it securely.
Magazine nut
When disassembling, the first thing you need to do is unscrew the magazine nut.
What do we see there? Here's what.
There is a locking pin on the forend that engages the ridges on the magazine nut. Remember the characteristic cracking sound when unscrewing a nut? This was done to more securely fix the nut and prevent it from unscrewing during shooting. The idea is good and necessary. Moreover, the pin, apparently, is made of normal steel and hardly wears out. But the nut suffers.
MP-155 magazine nut
Gate
It's a little more complicated here. At least that's how it happened for me. During the entire period of operation, I was never able to get the firing pin out of the bolt. The fault is with the pin, which is indicated by an arrow in the figure. It simply won't come out. I tried to knock it out, but it was all in vain. I’m simply afraid to use even more force because the part is serialized and you can’t easily buy a spare in a store, and it’s quite easy to ruin it. You literally have to pour WD-40 on the bolt wedge to wash out the dust from the gap between the wedge and the bolt body. By the way, the side parts of the shutter are polished rather lousy. At least if I had the opportunity to get it, I would polish it.
As you know, the MP-155 USM is fixed with two pins in the receiver. The pins are inserted into the box until they click. It is worth noting here that they are of different lengths. And during assembly it is worth installing each one in its place.
The longer one is placed in the hole that is closer to the barrel. This is easy to determine by eye because the receiver in this part is thicker.
Cleaning the trigger itself is a separate “pleasure”. The trigger itself is assembled into a separate part, which is a definite plus. But if sand gets there, you will have to literally soak it in WD-40 before triggering.
It is almost impossible to get sand stuck to the lubricant inside the trigger any other way. A compressor with good pressure would be a good help here, but not everyone has one. By the way, the manufacturer strongly discourages disassembling the trigger yourself unless absolutely necessary. Therefore, everyone here invents their own method of cleaning.
For now, this is all I wanted to convey regarding the disassembly and assembly of the MP-155. In the next article we will talk about the nuances of operating and wearing this gun.
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Second step
Once the nuts are removed, remove the forend and move the bolt to the rear position. After completing these steps, disconnect the receiver and barrel, and then remove the charging handle. At this stage you will have to make a small physical effort. The handle must be pulled out so that it is perpendicular to the axis of the shutter. Now remove the piston, bolt carrier, bolt and recoil spring from the shooting unit. This MP-155 disassembly is incomplete. Weapons specialists do not recommend doing a full gun unnecessarily. It would be best to take the shooting unit to a service center.
