DIY repair mr 512

All-Russian Society of fans of pneumatic weapons

Little tricks for finalizing the MP-512

There are a lot of articles on the Internet on the revision of the Russian MP-512 pneumatics. Having carefully studied all the articles, I decided to share my experience.

Like all owners of this gun, I faced the problem of loosening the screws. Noticing that the iron in the wood began to wobble, he took a screwdriver and began to tighten the screws. When tightening the left side screw, I heard the characteristic crunch of a tree. The screw is not fully tightened, but the wood is already crunching! I unscrewed all the screws and separated the metal from the wood. I carefully studied the seat under the cylinder and realized that revision was inevitable. The left cheek of the stock on the inside has a milling more than necessary. As a result, the cylinder is not tight, there is a gap between the bracket and the left cheek of the stock. To fix the stock I used the available beech. I trimmed the rail so that its thickness corresponded to the milling depth. Cut to length and rounded the edges so that the rail fits exactly into the milled groove. Glued with PVA glue. It is advisable to compress the parts with clamps and leave for a day. After drying, I grinded off the excess with a file and adjusted the shape of the inner cavity to the protrusions of the cylinder. That's what I did:

Now the cylinder sits tightly into the tree, and the screws can be tightened with all the, so to speak, foolishness. The main thing ? do not rip off the thread.
One day the gun came as an unpleasant surprise. On the rear attachment bracket, the thread ripped off from recoil. There would be no happiness, but misfortune helped. I had to cut the M6 ​​thread. Household screws in pneumatics die after a few shots. Used an automobile hardened screw M6 with a half-countersunk head. The screw was cut in length so that, with optimal tightening, its threaded part did not protrude beyond the inner edge of the bracket, otherwise the cocking thrust would rest against it.
Before screwing in, I smeared the thread of the fastening screws with glue? Moment ?. This trick does not require much effort the next time it is disassembled, but it does away with self-unwinding.

Trigger upgrade

To begin with, I disassembled it, sanded the trigger and sear. The hammer was rounded and polished.

Further actions can only be carried out after grinding, otherwise you can make a mistake with the gaps! The whisper chamfer, which the cocking lever touches, I rounded, thereby reducing the friction force. I drilled a thin wall of the trigger housing, opposite the place where the sear touched the trigger. This is a technological window, it is necessary for tuning the mechanism.

The next task was to eliminate the idling of the trigger after the sear was disrupted. I used the article, which I see no reason to rewrite. The solution to this problem is very simple. A metal bar must be inserted inside the trigger return spring. The diameter should coincide with the inner diameter of the spring, and the length should be such that the trigger rests against it immediately after the sear is broken. The solution is brilliant. No dancing screws.
Now it is necessary to eliminate the idling of the trigger before the sear breaks off. For this, a non-drilled wall of the trigger is useful. We look through the technological hole. We push the trigger so that the sear remains 1 mm before it breaks off. We draw a risk at the end of the wall at the level of the front edge of the trigger. Using a caliper, we transfer this risk to the outer side of the thick wall of the trigger. Then, using a barbell, we apply a perpendicular line, spaced 4 mm from the edge of the thick wall. We get the crosshair. Punch exactly in the center of the crosshair and then drill a 3.2 mm hole. We cut the M4 thread.

We take the M4 screw, clamp it into the drill and remove the excess thread with a file. The thread should only remain for the wall thickness.

As a result of processing the screw with a file, its diameter will be 3.0 × 3.2 mm. You can now cut off the excess length.

The length of the screw should be such that, when fully tightened, it does not reach the fuse plate slightly, thereby ensuring normal operation. Have you adjusted the length? You can now screw it into place.

We assemble the entire mechanism without a bar inside the return spring and check it. What, the whisper breaks down? Do not be alarmed, it should be so. Then you need to be very careful. We look at how much we need to bring the trigger closer to the sear. We disassemble the mechanism and file our stop with a needle file from the side of the trigger perpendicular to the body for its entire length.

Now it remains to assemble the gun without unnecessary spare parts and enjoy comfortable shooting.

These photographs show that if you carve the sear yourself, you can increase the piston stroke of a millimeter by 4 × 5.

After reading the tips for installing a dovetail stop for optics, I carefully analyzed everything and focused on the following design. Stepped back from the back of the? Tail? 10 mm. Perpendicularly, in the horizontal plane, I drilled a hole with a diameter of 2.5 mm at the narrowing point. With the help of a core and a hammer, he slightly reined the hole with blows from above. I forcefully hammered into the hole a hairpin made from the drill shank. The length of the hairpin should correspond to the width of the dovetail, then it will not touch the skirts of passing girls. This design of the stop allows you to use any brackets.

The fact that the breech should be polished was mentioned in the articles of other authors. I propose a small tweak to help stabilize the bullet velocity. The transition from the plane of the breech to the barrel hole should have a radius of 0.5 mm. In this case, the bullet will neatly fit into the grooves at optimal load, and will not cut off some of the lead on the sharp edge. The rounded transition is made according to the muzzle chamfer principle, previously described by other authors, using a special copper mandrel.

I see no point in describing the molding of the leather cuff, since the cuff from Hunter's 440 enjoys great authority (read with an emphasis on the first syllable) among the owners of the MP-512.

P.S. Jokes about the mother-in-law should not be considered as a guide to action. The gifted are allowed to compose a joke 🙂

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Hello my dear reader! Today I will tell you about improving the performance characteristics of the air rifle MP-512. I will say right away - do not be afraid to climb into the insides of the rifle, because it can be put in the first place by the ease of disassembly / assembly.

What is an upgrade? Why is it done? And how much does it cost? - we will analyze all this using the example of an air rifle of domestic production MP-512.

Upgrade - replacement of some parts or improving their quality in order to improve the performance characteristics of any product. And they do it when the rifle ceases to suit the owner. For example, the power has decreased or you want to get more accuracy. It can cost from literally nothing to fabulous sums. But in our case, everything will not cost much.

Like everything, the main points are considered, so I am retiring. More accurate fine-tuning is also performed, but all of the above can be done by ABSOLUTELY ANY person with a minimum set of tools.

ZY The article was written by me personally, after these modifications the rifle is in working order and shoots better than before. NOBODY is responsible for your actions, it is everyone's choice - to leave it as it is or modify it.

They brought another air rifle for repair, I decided to show you how parts are worn out.

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What to do? or basic upgrade MP-512
So, you have acquired a rifle. Hopefully, you have carefully studied the classics of the genre of choice upon purchase and have chosen not a golf club. This guide to action is intended for people who know little about spring-piston pneumatics, it can break the rifle (how do I know your ability to work as a tool?), So the author does not bear any responsibility, except moral, for the consequences of some advice.
Now a number of disappointments await you. Firstly, the declared power “not higher than 7.5 J” does not mean the legal 175 m / s with a half-gram bullet, but the possibility of such. Most often it is from 150 to 170 m / s. Shooting from a freshly acquired rifle is categorically not recommended - at best, the cuff will quickly become unusable, at worst, you will scratch the cylinder with factory debris (which has been less common recently, but still occurs).

———————————————
Weighting agent.
Depending on the length and filling of the cavity with lead, the mass ranges from 20 to 65 g. The total length can be increased to 60 mm, in the absence of a guide - up to 100 mm, the mass can be increased to 100 g.
Guide.
For a more accurate fit into the hole of the KSM, the size Ф12 is adjusted in place so that the guide fits snugly in the KSM.

We are sitting in ambush, me and my "Murka" ...
(from the experience)

Replacing the spring, cuff and barrel gasket on the MP-512 (Murka), based on the MP-512-22 air rifle

Having broken the rifle, unscrew the stock fastening screws: two on the sides closer to the barrel coupling and one at the bottom on the forend.

We remove the compressor with the barrel, unscrew the axial bolt securing the barrel and separate the barrel from the compressor.

The block is held in place by two pins.

Lubricate the pin 1 of the fastening inside the block, clamp the compressor in the machine or clamp in order to remove the block with the trigger. We squeeze the block so as to relieve the stress on the pin.

Quite often, simply pressing the pin with a finger is enough, and it comes out freely, but it happens that it “bites” in the hole of the trigger, which rotates on it. Try wiggling the hook while squeezing out the pin. If you cannot remove the pin with your hands, then lightly tap with a mallet or hammer through the drift. It is not necessary to apply much effort, in addition, there are recesses on the pin at both ends, which fix it in the compressor, preventing it from moving and also interfering with its extraction.

4) We extract the contents of the compressor.

The cuffs on the IZH rifles are quite easy to remove and put on. It is enough to pry it off with a knife or screwdriver. You can put on a new one by warming it up in hot water.

We do not recommend using soft cuffs as they can easily fly off the piston when the rifle is cocked.

We also recommend removing all burrs and slightly sharpening the sharp edges of the technological holes under the trigger and the piston engagement in the compressor before inserting the piston there. This will help to avoid scoring, which means that the cuff is guaranteed not to be melted at the first shots, which often come with a diesel engine.

6) Replacing the barrel gasket.

With an awl or a thin screwdriver, remove the gasket if its inner diameter is less than 3.5 mm and install another, in our case the inner diameter is 5 mm.

We will supply gas instead of the standard twisted one. It eliminates vibration and slightly reduces sound during a shot. Install it with the body of the spring in the piston and the rod in the block. Thus, the piston is guaranteed not to scuff the body of the GP, which sometimes happens on the MP-512. We also additionally centered the spring body in the piston with electrical tape, because The design of the existing GP does not provide for centering elements of the body in the piston, and only a centering washer for the GP rod is supplied with the spring.

Moreover, if the depth of the shoe is less than 32mm, then it will need to be milled to a depth of 32mm.

In our case, the rifle has a block with a depth of 31.5 mm and does not require milling.

We got a preload of 3mm, with which, this rifle, the rifle was cocked. The compression should not be less than 3mm for all GPUs. In our case, we were additionally forced to grind off the inner side of the GP centering washer in order to increase its stroke. without this it was impossible to cock her. Compression greater than 3mm is not a disadvantage. The main thing is that your rifle is cocked.

If you have questions and need a consultation, there is no desire to stir up tons of information in the search, welcom.

HUGE REQUEST: Negative and emotional outbursts are not woven into the topic. If you have anything to help, we are always happy.

For starters, a few basic sketches, links and information:

Dimensions of the backdrop for the rug GX440:

roller for cylinder polishing (textolite):

Bushing in the bypass (brass) with a seal (The O-ring can be cut from a standard bypass rubber, leather, hard oil-resistant rubber, from a cuff or from a polyurethane translucent gasket for mixers.):

Guide and weight for the GC rug:

Muzzles of 2 types, universal (both under the optics and under the front sight) and under the optics:

The weighting agent increases the mass, and, accordingly, the inertia of the piston. This allows it to more efficiently pressurize air at the end of the stroke, compensating for the dropped spring pressure and reducing the rebound from the air cushion. The mass is selected based on the parameters of the spring pressure and the mass of the bullet (at a constant stroke).

The guide reduces spring bending and partially eliminates piston skew. This reduces lateral vibration (comfortable shooting, higher accuracy), increases the survivability of the cylinder (the piston scratches the cylinder less) and springs.

Epoxidized cuff: Provides a speed increase of approx. - 5-10m / s. The sealed cuff has sufficient rigidity, is well obturated due to crushing of the upper edge, which continues to operate normally, and slightly, but reduces the dead volume in front of the piston.

The muzzle-weighting agent, due to the same increase in inertia, reduces barrel vibrations (longitudinal and transverse), which increases the accuracy. Simplifies the aiming process when shooting without a stop.

The sleeve reduces the dead (incompressible) volume to a value where the air is not yet decelerated, but the pressure reaches a maximum, plus the possibility of better sealing due to less crease and greater sealing of the protruding sealing ring (standard crumples when the barrel is locked).

Having installed this set + a spring from the GC 440 - we get from 12 to 15 J, which is approximately 230-260m / s GC bullets (which I recommend for a murka!)
=====================================================================

If you are the proud owner of a DIY constructor called MP-512, bought in a gun store under the influence of the nostalgic: “I used to shoot like that in my childhood, at a shooting range”. If, having already shot a “couple of boxes” of caps under the loud name “Diabolo”, you still cannot get into a tin can at a picnic post-fire. If, after reading on the Internet about the hidden possibilities of the aforementioned product, you decide to roll up your sleeves, armed with a sledgehammer and a file, and still reveal these possibilities, then I will try to help you with this by outlining the accumulated experience in several articles devoted to the modernization of this wonderful rifle.

So, we will start by driving (if available) the other half from the dressing table or simply standing in front of the mirror, we will engage in auto-training. No, it's not trivial: “I can do EVERYTHING. ”(18 times to be believed). This is, looking into your eyes, repeating: “I will not swear, I will not swear, I do not know how to swear. “, And so on, until the achieved effect passes into the stage:“ having fallen asleep about a cat, call it a cat ”. Otherwise, poor designers of IZH fur (in absentia), hammers, chisels, taps and drills (as well as your homemade ones) run the risk of drawing from your vocabulary a few florid expressions, for the invention of which you will call upon all your imagination.

I'll start by telling you how to make a soft trigger. Many, during modernization, think that it is necessary to start with replacing the spring, installing a weighting agent in the piston, perversions in a rigid form above the cylinder, proudly calling this action “polishing”, but in fact it is necessary to start with the modernization of the trigger. Because the exact shot depends on it.

polifem Mar 30, 2012 2:19 pm

Introduction
Domestic MP-512 (or, as it is also called "Murka") - the most common air rifle in Russia. It gained such wide popularity largely due to the ease of modernization. There are certain flaws in the design of the rifle, most of which are eliminated with a file. Murka has a large margin of safety, which also contributes to the upgrade.
The method described below is called "upgrade from gnom" (by the nickname of the person who largely invented and systematized the MP-512 upgrade). It is worth saying that this is a description of an upgrade for a standard Murka. Modernization of “Elegance” and “New Design” has its own subtleties.
This article covers only the rifle accuracy part of the upgrade. How to increase the power read in another article.
Platoon
The first thing that needs to be finalized in the rifle is the platoon. The wrong angle of engagement of the rod and the piston leads to the fact that the piston often lifts the cylinder. The angle must be changed so that when cocking the rod pushes the piston down a little. accordingly, it is necessary to turn the plane of the hook by 5 degrees.

Trigger mechanism
1. Making the descent softer.

To make the descent softer, you need:

change the angle of the sear with the piston;
change the angle of the trigger ledge;
grind and polish the contact surfaces of the sear and piston;
to grind and polish the contacting surfaces of the sear and SC;
make sure that there are no burrs on the sear axis, and if there are any, remove them.

First, the piston-sear engagement is corrected. Before processing, a significant torque is transmitted to the sear from the piston, a considerable part of which, due to the simplicity of the design, is transmitted to the SC. It is necessary to correct: we draw a perpendicular to the sear and from it another 2-3 grams to the side.

Further - the revision of the trigger (SK). The ex-factory trigger ledge has an irregular angle, the radius from the axis of rotation to the end of the ledge is greater than the radius from the axis to the base. As a result, when you press the SC, we act on the sear in the direction of increasing the engagement with the piston against the force of the mainspring.
Ideally, the radius from the axis to any point on the ledge should be equal, but unfortunately, it is technologically very difficult to infer the radius on the ledge. In addition, it is quite enough to simply re-sharpen the ledge so that it is parallel to the sear shelf. The most suitable option is somewhere in the range of 112 to 115 degrees.

The whispering shelf just needs to be slightly trimmed. After the file, there is processing with sandpaper on a mandrel and final finishing with GOI paste. The edges of the descent must be sharp.
As a result of these manipulations, the descent force decreases from the passport 2-3.5 kg to 400-500 g.

2. Making the descent shorter.
To make the descent shorter, there are two simple methods:
1) Install a transverse screw / pin that will limit the forward movement of the SC when cocking. Then the length of the hook of the SC ledge with the sear will decrease.
2) Decrease the length of the shoulder on the SC. This method is bad in that it is irreversible.

3. Eliminate the "failure"
"Failure" (idling of the SC after the sear is broken) is removed by installing a piece of a rod from a gel pen, or some other cylinder of a suitable length and diameter, into the SC spring.

Muzzle bevel
Many people complain that the factory muzzle chamfer does not suit them. But as practice shows, the factory chamfer, although not very beautiful, is usually even. And if you are not sure that you will make the chamfer better, you should not touch it. Sometimes the barrel can be pinched under the fly. In this case, it is necessary to cut the trunk, make a new chamfer and, possibly, cut the threads.

Weighting
For accurate shooting, the rifle must be weighted.It is necessary to install a muzzle weighing 300-350 grams on the barrel, you can also 400, but this is not for everybody. The bed must be filled with polyurethane foam with lead shot. Weight is selected experimentally - to an acceptable balance. It is desirable that the rifle weighs at least 3.5 kg.
Here are some drawings of muzzles.

Conclusion
If everything is done correctly, then we will get a fairly accurate rifle (accuracy of about 10 mm at a distance of 25 m). Then you can increase the power.

This is the second part of the article about the MP-512 upgrade. In the first part, we modified the platoon, trigger mechanism, muzzle chamfer and rifle balance. Now it's time to increase the power.

Back boring
To begin with, it is worth saying that the "back" is the part marked on the explosion diagram of the rifle (you can see it here) with the number 18. That is. “Backdrop” in this case is the block of the trigger mechanism.
The spring depression must be increased to approximately 31 mm. The bottom should be flat - this is important. If there is no way to bore with a milling cutter, but there is only a drill with an angle of 120 degrees - at least place some flat washer under the spring. Usually a 1 ruble coin is suitable.
This operation is necessary so that a longer spring from the Gamo Hunter 440 can be put into the rifle. The “back” does not need to be bored, but then the spring will have to be cut.

Weighting agent
The piston of the rifle must be made heavier. To do this, you need a weighting agent, its mass should be approximately equal to the mass of the bullet you are going to shoot, multiplied by 150. The weighting agent can be ordered from a turner or bought on the Internet. Some MP-512 have a beveled piston bottom, and when installing a weighting agent, a skew of the piston inside the cylinder may occur.

Bypass
The diameter of the bypass hole must be reduced; for this, a special sleeve is used, which is inserted into the rubber gasket of the bypass, it, like the weighting agent, can be ordered from a turner or bought.

To reduce bypass, you can also use a piece of the refill from the gel pen. To prevent it from being pushed out by the air stream, it is necessary to make a hat at one of the ends.

Breech barrel
The factory breech of the barrel has a smooth approach to the rifling and, accordingly, a low pulling force of the bullet - it must be corrected.
To begin with, you need to grind an abstract pig into a standard barrel thread. Then pull out the bolt (the wedge that holds the barrel closed) and insert the 9 mm drill shank instead. Resting the ingot on something, we strike with a heavier hammer on the drill from above. The barrel should come out of the sleeve by about 1.5-2 cm.
We cut off the protruding part and level the breech with a wide flat file, sometimes attaching the barrel and checking the position of the coupling relative to the compressor in the closed state. Then we wind a little sandpaper (for the beginning of the 600th) on the same file and grind, if desired, repeat with 1000 sandpaper until an acceptable result is obtained.
Because the barrel has moved, it is necessary to re-make the groove under the axis of the barrel. We'll have to do the breech bevel - the method is the same as for the muzzle.

Conclusion
Then you can fine-tune the rifle and achieve maximum results. See how this is done here.
If you did everything right, then you will have an excellent rifle with a power of 18-20 J and an accuracy of 1-2 cm by 25 meters. It will delight you both when shooting at paper and when hunting at distances of up to 50 meters. The MP-512AP is a rifle of a completely different level. Devoid of her childhood illnesses such as vibration, poor descent, poor balance. Powerful - an average result of 250 m / s with a 0.5 g bullet, a good result of 280 m / s. Accurate - accuracy at the level of more expensive rifles, often even surpassing them. At a much lower cost, it will successfully compete with rifles Gamo, Krosman, Norik and other rifles of the middle price level.
The article is honestly scammed from here, because from my own words I would still describe the process in the same way.
There will be questions about the "subtleties" of the apa, ask with pleasure I will answer all questions, to the best of my knowledge of course

Message alexyurist »04 Oct 2009, 15:39

In this review I will try to tell you about my experience with upgrading and repairing the MP-512 rifle, with pictures and detailed explanations.
As rightly noted in my other review pri-klad, winter is approaching - the hottest time for the upgrader, who, due to unimportant weather conditions outside the window, has to be bored at home for a long time.
Let's get started.

MP-512. AP and repair through the eyes of the owner

There is a standard set of “improvements” that are recommended to be implemented:

Refinement of the platoon - this includes changing the contact angle on the cocking rod and the reciprocal engagement of the piston, installing caprolon, fluoroplastic gaskets in the places where the cocking thrust moves, installing a caprolon or fluoroplastic “ski” instead of a standard roller.
This revision will allow to avoid the occurrence of scoring on the inner surface of the compressor, on the leading piston belts, to make the rifle cocking softer, the installation of gaskets and skis will also facilitate and soften the cocking, in addition, eliminate clatter and ringing when manipulating the rifle and firing;

Refinement of the descent - this includes changing the angle of contact of the sear with the trigger, changing the angle of contact of the sear with the corresponding piston engagement, rounding of the edges on the trigger.
Allows you to reduce the descent force from the factory 1.5-3 kg to 0.4 - 0.7 kg, to make the descent more comfortable;

Finalization of the breech of the barrel, making a new breech chamfer - a "bucket" is drilled in the breech of the barrel on the factory muck, into which the bullet is inserted, the bullet is simply put there, it does not get into the grooves, when fired, it is driven onto the rifling by air pressure, and is fired from the barrel. This flaw greatly affects the accuracy and accuracy of the rifle, tk. there is no uniformity in setting the bullet on the rifling, in addition, in the factory version, the bullet has a relatively low breakaway force, which does not allow achieving maximum speed from the rifle due to the fact that the bullet starts from the spot much earlier than the peak pressure in the cylinder occurs. AP - during the AP, the breech of the barrel is extended to the required distance from the barrel coupling, the breech chamfer of the optimal shape is cut and made, which allows the bullet to be correctly positioned on the rifling, which allows to increase the bullet pull-off force.

Modification of the muzzle chamfer of the barrel - often not required, you need to look at a specific instance of the rifle, if the chamfer is made crooked or carelessly, then the accuracy and accuracy of the rifle may suffer.

Weighting the rifle - in the factory version, the rifle is lightweight, which negatively affects the recoil and accuracy of the rifle, the weight of the rifle consists in screwing the muzzle or moderator onto the barrel, the moderator will allow, in addition to weighting, to make the sound of a shot quieter, weighting the bed, the method of weighting depends on the material of the bed, and also on how much you need to weight the rifle.

Installing a more powerful spring in the rifle - allows you to increase the initial speed of the bullet, and therefore the power. Although I reached the 170 m / s declared by the manufacturer without much difficulty and on a standard spring. It is also possible to install a gas spring in the rifle, it makes the rifle's shot clearer and more comfortable due to the absence of vibration of the spring after the shot, makes the characteristics of the shot flatter due to the fact that the initial and final force of the spring do not differ as much as in the coil spring. To do this, it is necessary to drill the backing plate to a depth of 29-31 mm.

Installing a new stock on a rifle, the wooden bed of the moors is even more or less, but the plastic one, hmm. not really. but this is not for everybody.

Installation in the bypass throttling sleeve - allows you to somewhat align the characteristics of the shot due to a certain slowdown in the moment of bullet starting (here I can be mistaken in theory, but in practice it works unambiguously), at the same time the increase in bullet speed occurs due to a decrease in the dead volume of the bypass;

Reduction of dead volume - achieved by installing the bushing in the bypass (see above), as well as filling the groove, or, what is better, installing the so-called "Petrukhina" cuffs. By reducing the dead volume, the pressure at the end of the piston stroke increases, and, accordingly, the bullet speed / rifle power;

For work, you will need good lighting of the work site, straight hands, a caliper, a drill, different drills, different files, different files, emery skins, a vice, a hammer, an abstract metal ingot, an M12 * 1 tap, cotton wool (cotton pads), cotton swabs , thick fishing line, SHRUS-4, ballistol, kerosene / gasoline / white spirit, drilling, turning and milling machines.

I will explain in the order of the points.

The air rifle produced by the IZHEVSK MECHANICAL PLANT MP-512 (popularly referred to as Murka) is the most famous and most bought air rifle. In terms of popularity, only MAKAROV'S PNEUMATIC GUN can be compared with it. There are several reasons for this. At the end of the last century, there was simply no other choice. If in Moscow and St. Petersburg there was at least some choice, then on the outskirts of the country only the air rifle MP-512 Murka lay in the windows of arms stores. Later, when Spanish air rifles appeared in stores, price was the deciding factor. The MP-512 air rifle cost four times cheaper and, when installing a powerful spring, was not much inferior to the Spaniards. Very powerful and very high quality air rifles of the German company Diana cost so much that they seemed to come from another life.

The MP-512 air rifle appeared on sale in 1998. It was produced in two versions, with a wooden and plastic stock. Now in the caliber of 4.5 mm, three versions of the MP-512 air rifle are produced, which differ only in appearance. Their iron is absolutely the same and slightly different than in the previous samples. Therefore, many recommendations and articles about operation, methods of improvement and strengthening can be forgotten. There is a reinforced version with a capacity of twenty-five joules. It is called the MP-512m air rifle and is available in 4.5 and 5.5 mm calibers. After long throwing and cursing from users, manufacturers finally settled on a plastic barrel coupling. We haven't heard about the massive destruction of plastic couplings recently, but plastic does not add optimism to users.

The photo shows from top to bottom - old steel sleeve, old plastic sleeve, new plastic sleeve.
Of the positive results of the modernization, the trigger block can be noted. The hole where the spring rests in the block is machined to its full depth, which makes it easy to change the native spring to a more powerful Spanish one. Previously, to install a Spanish spring, you had to look for a turner or cut off several turns of the spring. The barrels of all versions of the MP-512 air rifle are four hundred and fifty millimeters long. The total length of the rifle is one hundred and nine centimeters.

The device is the most common, the classic scheme with a breaking barrel. To load the rifle, it is necessary to break the barrel all the way. In this case, the barrel through the cocking lever pushes the piston back, which in turn compresses the mainspring. In the extreme rear position, the piston, with its protrusion, cocks the trigger and clings to the sear. The diagram of the cocked trigger mechanism MP-512 is shown in the photo.

According to the scheme, it is clear that the piston is held by the sear hook, and the sear itself is held by the trigger “step”. When the trigger is pulled, it releases the sear, under the action of a spring, its right side rises sharply, and the left one falls down.The protrusion of the piston disengages, and the piston itself begins to move forward, compressing the air and firing a shot. The trigger is not adjustable. Therefore, all adjustments are made with a file.

The photo shows the details of the trigger.

The MP-512 air rifle has only two advantages: a low price and a very decent barrel. Of course, it cannot be compared with the barrel from Walther, but it must be borne in mind that the entire rifle costs almost half as much as the barrel from Walther. Izhevsk trunks can not be cleaned for years and the heap practically does not creep.
There are many more disadvantages. The main drawback is a terrible descent - tight, long and uneven (the effort either increases or decreases). Moreover, the effort on the trigger directly depends on the power of the spring - the more powerful it is, the more tight the descent. To improve the descent, it is necessary to halve the step on the trigger and polish the rubbing surfaces.

The photographs show a comparison of the original trigger of the MP-512 air rifle with the modernized one - the step is halved and its platform is polished. The descent is shorter, more uniform and predictable.

Some authors suggest rounding the trigger angle to a radius of nineteen. I have no idea how to do it technically. And most importantly, I don't know if the descent will be predictable in this case.
Even in the twenty-first century, the designers of the Izhevsk plant were unable to equip their air rifle with a rubber insulating ring on the barrel. Air breakthrough is eliminated by a piece of rubber tube inserted into the bypass hole. As a result, a huge parasitic capacity arises in the bypass hole, which reduces the muzzle velocity and rifle power.
Always the weak point was the fastening of the rifle iron in the stock. With a weak tightening of the screws, the iron dangles, with a strong tightening, the screws rest against the piston rod and slow it down - the only way out is to put washers. Air rifle MP-512 has too free entrance for a bullet. Previously, this was treated by cutting the edge of the trunk, but with a plastic sleeve, this operation became impossible.

Here in the photo is a variant of the MP-512 with an increased piston stroke length. I don’t know how much it can be considered MURKA? She even has a different bar for optics.
Now you can buy a gas spring. It has several advantages over a steel coil spring. The most important thing is that the gas spring does not sit down, so the Murka can be worn charged for an unlimited time.

The elimination of the parasitic bypass volume is achieved by making a special sleeve.

The MP-512 air rifle is usually converted into something short while maintaining power. The simplest option is the kulak sawn-off shotgun.

The photo shows a Murka specially converted for hunting duck and pheasant. The barrel and butt are cut to fit the weapon into the bag. The spring is accordingly Spanish. A telescopic sight with a large lens allows (at minimum magnification) to shoot confidently at dusk. The total length of the shortened MP-512 air rifle is sixty-five centimeters. Barrel length two hundred and eighty millimeters. Since in spring piston air rifles, the bullet gains most of the speed in the first twenty-five centimeters of the barrel, the power is practically not affected.

Another version of the shortened rifle. The barrel is shorter than the previous model, but the owner claims that the speed with a gas spring is 220 meters per second. For some reason, the owner put a muffler on Murka, but in my opinion the ringing of the spring and the blow of the piston drowns out all other sounds. The sight is primitive VOM-3.5, withstands about half a year of not very active operation, and then the lenses begin to ring.
Konstantin Plakhov was a big fan of altering air rifles MP-512. Here are photos of some of his products.

The photo shows how the trigger is moved to the forward position.

A pistol based on the MP-512 air rifle.

The same but from a different master.

For a rather primitive rifle (and what else to call a product that does not even have an insulating rubber band on the barrel), they make an extra-class stock. This is absolutely incomprehensible to me, if there is money for a box, then buy something decent.

Pay attention to the bottom photo. The owner makes a short version, so he transferred the telescopic sight from the bar to the sleeve. This eliminates the effect of barrel play on firing accuracy. Unfortunately, you can't put a sight on a modern plastic sleeve.

This option has nothing to do with pneumatics, but is made on the basis of the MP-512. A laser is installed on the rifle, and the laser receivers are worn on the owner's head. This is how grown-up uncles play war.

MODEL MP-512-28 is the most primitive and simplified version, the dovetail-type optical sight attachment has been replaced with two indistinct scratches on the surface of the compression chamber. The price is about four thousand. She is not in the photo, but mentally remove the mount for the telescopic sight and she will be.

MODEL MP-512-22 is an old version of a rifle with a plastic stock. The price is four thousand one hundred rubles.

MODEL MP-512-36 updated design, plastic stock. The price is four thousand one hundred rubles.

MODEL MP-512-26 updated barrel design, birch stock. The price is five thousand six hundred rubles.

MODEL MP512-24 updated barrel design, combined birch stock. The price is six thousand one hundred rubles

MODEL MP-512 updated design, combined walnut stock, laser engraving. The price is almost eight thousand rubles.