I do not remember in the comments to which article and by whom, but it was proposed to make several materials in which the basic principles of the operation of firearms, as well as individual nuances of a particular system, would be described. This was proposed in the context of the popularization of weapons, since for many, that the automatic system with a long barrel stroke, that the free bolt is just a set of words and nothing more. Well, about the fact that people are pulling the trigger and so on, you can not even mention. Let's start right away from the complex, namely just from the automation systems, since, having dealt with them, people will at least have an understanding of how this or that sample works.
Usually, in reviews of weapons, I try to describe at least briefly how automation works, but sometimes there are several articles in a row about weapons with the same automation system, as a result, writing the same thing is not at all interesting, and I don't always want to describe in detail what, how and where he is going. In this material, I would like to cover at least what has been and is being used in firearms at the moment, of course, with specific examples. The material will be large, tedious in places, I will try to write without using terms, that is, roughly speaking, I will explain it on my fingers. So whoever is in the topic can safely skip the article, since you will not learn anything new from it, but who wants to figure out how and what works, then it is imperative to read it. Maybe new visitors will be added at the expense of this article in the sections "Individual weapons" and Sniper weapons ", otherwise we are sitting here with our own company, we will expand.
Free shutter automation system
Let's start with the simplest thing, namely a free-breech automation system. The closest example to our compatriots will be the Makarov pistol, in addition, the free breechblock is often used in submachine guns and in those samples that use low-power ammunition. In pistols, the free breechblock is used mainly with cartridges with a small kinetic energy of the bullet, the limit for such a system can be called 9x19 ammunition, for which there are several models of pistols with automatic breechblock. But such a weapon works, in the literal sense, at the limit of its capabilities, which is why its resource is very small, and the requirements for the quality of materials are very high, which naturally affects the cost. If we talk about submachine guns, then in them the automatic breechblock system is used more widely and with a wide variety of ammunition. But first things first.
Breech block automation system for pistols
We will disassemble the automation system with a free shutter for pistols using the example of the same PM, since for people interested in weapons there will always be an opportunity to get acquainted with this pistol in view of its wide distribution, at least in the "traumatic" version, which does not differ in the automation system from the original … Inside the casing of the weapon, the very part for which the cartridge is pulled from the store to the chamber, the uppermost movable part of the pistol, the bolt is located, therefore for most pistols in the description they say not just a bolt, but a bolt casing, since these are two parts rigidly interconnected. There are options for pistols where the shutter is represented by a separate part of its own, but there are not many of them. Despite the fact that the automatic system is with a free breech, the breech is actually not so free, its movement is impeded by the return spring of the weapon, which is entwined around the barrel in the Makarov pistol. The return spring rests against the front of the bolt casing, thus, in order for the bolt casing and, accordingly, the bolt itself to be in its extreme rear position, it is necessary to compress the return spring. Well, now how does it all work.
As you know, the bullet moves along the bore due to the fact that the powder during its combustion emits combustion products in a volume that significantly exceeds the volume of the powder itself. Due to this phenomenon, the pressure increases very quickly between the sleeve and the bullet, respectively, a larger volume is required to reduce this pressure. The increase in the volume free for the powder gases occurs precisely due to the fact that the bullet moves along the barrel and the distance between the sleeve and the bullet increases. To make it clearer, you can imagine all this in the form of a piston, but with one caveat. The powder gases, expanding, press not only on the bullet itself, but also on the walls of the barrel bore, as well as on the bottom of the sleeve. If the sleeve had not been propped up by the bolt, then it would have flown out of the chamber in the same way as the bullet, but since the weight of the bolt, casing and sleeve is greater than the weight of the bullet, and plus to the entire bolt casing does not allow the return spring to move freely, the sleeve remains in the chamber.
It will be quite timely to ask how the recharge takes place in this case. I will try to explain the other way with a simpler example. If you take two metal balls with a large difference in mass and put a compressed coil spring between them, then when the spring straightens and pushes the balls, they will move at different speeds, and if the difference in weight is very large, then one of the balls may stay on location. In our case, in order to ensure the trouble-free and correct operation of the weapon's automation system, it is necessary to ensure that the bolt casing moves after the bullet leaves the barrel, that is, so that not the powder gases push the bolt sleeve, but the heavy bolt casing due to Having retained the energy received through the sleeve from the powder gases, he pulled the sleeve out of the chamber.
I feel the forest has piled up, "imagine this, imagine this", because the lite-version of the description of the operation of the automation system with a free shutter:
When fired, the propellant gases expand, push the bullet at a high speed along the bore, press on the sleeve, which transfers the energy received from the propellant gases to the breech casing. Due to the greater mass of the shutter casing, in comparison with the bullet, its speed is much less than the bullet speed, but on the contrary, due to the greater mass, the shutter casing gains speed more slowly, therefore it is often said that the shutter casing begins to move after the bullet has left trunk, which is not entirely true. Thus, the automation system can be represented as a system with two movable pistons in one cylinder, differing in the force required for their movement. Well, speaking roughly and not taking into account the fact that one of the pistons continues to move even when the second one has jumped out of the cylinder and the pressure in it has returned to normal.
Well, to make it completely clear, let's try to go through the points of what happens when fired using the example of a Makarov pistol:
1. The gunpowder ignites, starts to burn, increasing the pressure between the cartridge case and the bullet.
2. The bullet moves along the barrel, picking up speed, the casing-bolt begins to accelerate very, very slowly, practically imperceptibly.
3. The bullet leaves the barrel of the weapon, the bolt, due to its mass, continues to move, even though nothing else pushes it through the sleeve. During the movement of the shutter, the return spring is constantly compressed.
4. The bolt casing removes the spent cartridge case from the chamber and throws it out through the spent cartridge case window.
5. Having reached its extreme rear point, the bolt cover cocks the weapon trigger and stops
6. Since the return spring is compressed, after stopping the casing-shutter it tries to straighten, as a result the casing-shutter starts to move forward.
7. In the process of movement of the casing-shutter, a new cartridge is removed from the magazine, which is simply pushed forward.
8. The bolt cover inserts a new cartridge into the chamber and stops.
Despite the fact that everything is really very simple, even such an automation system may not work correctly. Above was an example with two metal balls of different masses, between which a compressed spring was laid. This example most clearly demonstrates two options for the malfunctioning of the weapon's automation system. In the first variant, when one of the balls is too heavy, in comparison with the second, it simply will not budge. In our case, this will mean that the shutter casing will simply support the sleeve and no reloading will occur. In the second case of improper operation of the automatic system with a free shutter, the shutter can begin to move even before the bullet leaves the barrel, respectively, the thin walls of the sleeve will take all the "blow" from the powder gases onto themselves and most quickly will not withstand or deform. Both are not good for us, since a deformed or torn sleeve can jam the shutter casing, and the bursting powder gases through the torn sleeve, instead of pushing the bullet along the barrel, will simply go into the air, respectively, the bullet will move more slowly.
It may seem that ensuring the correct operation of the automation system is an incredibly difficult task associated with an accurate calculation of the weight of the shutter casing, but this is not so. In the case of balls of different masses, between which a compressed spring is laid, we can really "play" only with weight and nothing else. In the case of a pistol, we have another opportunity to act on this system, namely through the return spring. Since the return spring is directly connected with the casing-shutter, then, by changing its stiffness, we can change the speed of movement of the casing-shutter without changing its weight.
Naturally, examples of improper operation of the automation system cannot be found in military weapons, since such samples are designed by specialists and similar "childhood diseases" are a shame for the designer. And military ammunition is more or less stable in terms of energy. It is possible to meet the incorrect operation of the automatic system with a free shutter in pistols only in very old samples or in case of an outright marriage in the production of weapons or ammunition. But there is an opportunity to look at this disgrace. Provided such an opportunity traumatic weapon. I will make a reservation right away that the reason for the malfunctioning of the automatic system with a free shutter in traumatic conditions is not a mistake in the design of the weapon. The real reason is that traumatic cartridges have a very large spread in their kinetic energy. Here's an example. The weapon is designed to use quite powerful ammunition, the seller decided to sell very weak cartridges to the owner of the pistol, praising them and calling them ideal for practice shooting, here is the inscription on the box "Training". Having decided to shoot and hone his skills, the owner of the pistol unexpectedly discovered that his pistol had turned from a self-loading weapon into a manual reloading weapon, since the energy of weak cartridges was not enough for the bolt to move all the way back. Naturally, the pistol and the manufacturers are "to blame" for this, but if you replace the return spring with a weaker one, then everything will work like clockwork. Or the opposite example. Weapons designed for weak cartridges are loaded with more powerful ones. As a result, when firing, the shells look like it is not clear what, and the pistol itself periodically fails due to stuck shells. Let's omit the point that in weak samples, not only the automation system is designed to use weak cartridges and the use of more powerful ones will lead to a weapon breakdown, but in this case, a stiffer return spring will ensure reliable operation of the automation system, although not for a long time.
In general, the free breech automatic system has established itself in pistols as the simplest and most reliable, and if it were not for the limitations on the power of ammunition, then the free breech would have become the most common in pistols. However, they were once the most common when self-loading pistols first appeared.
Breechblock automation system for submachine guns
In submachine guns, the free breechblock both occupied its leading place in distribution, and continues to occupy, although other automation systems are trying to squeeze it out, while the leadership remains with it. The reason for this spread lies not in the fact that only low-power cartridges are used in the PP with a free shutter, just here there is a much greater variety of ammunition, but in the fact that the designers found solutions that were unacceptable in pistols.
The simplest solution to this problem is a long shutter travel. Everything works in the same way as in pistols, but at the same time the bolt has a longer stroke, which reduces the load on the weapon parts. In pistols, unfortunately, this is difficult to apply, since the dimensions of the weapon will increase dramatically. An example of such an automation system can be the domestic submachine gun Kedr, which you can also get acquainted with on the example of its traumatic version of Esaul, although it is not very common and is deprived of the ability to conduct automatic fire, so the acquaintance is incomplete.
A much more tricky way is the automation system, in which the shot is fired from an open bolt. In the previously considered options, the normal position of the bolt before the shot is its extreme forward, when it rests against the breech of the barrel, in this case everything is exactly the opposite. The normal position of the bolt is its extreme rear, with a compressed return spring. Thus, when firing, the bolt is released, on its way forward it picks up the cartridge from the store, inserts it into the chamber and breaks the primer.
Such an automation system has both its pros and cons. On the positive side, it is worth mentioning that the weapon can use powerful enough ammunition while maintaining a relatively short shutter travel. This happens because in order for the shutter to start moving in its opposite direction, it must first be stopped, that is, part of the energy of the powder gases is spent on stopping the shutter and part for it to start moving back. The negative quality is that the moving parts of the weapon knock it down from the aiming point even before the shot, therefore, the weapon becomes less accurate. I'll try to describe how it all works point by point.
1. The bolt is in the rearmost position, the chamber is empty, the return spring is compressed.
2. The bolt starts to move forward, picks up a new cartridge from the magazine.
3. The bolt inserts a new cartridge into the chamber and breaks the primer.
4. A shot is fired, the powder gases push the bullet along the barrel, as well as the bolt through the sleeve.
5. Shutter stops
6. The shutter, having received energy from the powder gases through the sleeve, begins to move back.
7. The bolt removes the spent cartridge case from the chamber and discards it.
8. Having reached its extreme rear point, the bolt stops by compressing the return spring (for single fire mode).
In general, everything is simple, you can even say that everything is the same, just the numbering of actions has been shifted. An example of the application of such an automation system can be at least a PCA. The free shutter automation system is essentially the first automation system on the basis of which the first self-loading weapons were made, so we can say that this system is one of the oldest. Despite all its limitations on the power of ammunition, it still remains a fairly common system, and its reliability and ease of production make many weapons manufacturers pay attention to it.
Fixed shutter automation system
Unlike the previous automation system, a fixed shutter is very rare, one might even say that it does not occur at all, but since such an automation system exists, it cannot be missed, especially since it, like the previous one, does not rigidly lock the barrel bore so they are somewhat similar. At the same time, a fixed-breech automation system is a kind of exception, since all other options used in self-loading weapons cannot do without it. There are very, very few weapons with such an automation system, the most famous is the Mannlicher M1894 pistol.
You won't have to paint this automation system for a long time, everything works very simply and clearly. As you know, there are grooves in the bore of the weapon, and the bullet itself must pass quite tightly along the bore for the most efficient use of powder gases. Thus, if the barrel of the weapon were movable, then when fired, the bullet would push it forward due to the frictional force that occurs when it passes along the barrel. It is on the basis of the movable barrel that the automatic with a fixed shutter works. In other words, instead of using a movable shutter for reloading, pushed by the energy obtained from the powder gases, a completely different principle of operation was used, in which the powder gases, although they participate, are not directly related to the automation system. It all works as follows.
1. When the powder charge is ignited, the bullet begins to move along the barrel, pushed by the powder gases, while the barrel of the weapon, having a greater mass than the bullet, also begins to move forward, but this is almost imperceptible.
2. The bullet leaves the barrel of the weapon, and the barrel itself, having received enough energy from the bullet for a full rollback forward, begins to move, compressing the return spring.
3. The barrel goes forward, freeing the spent cartridge case, which falls out, having received the long-awaited freedom, independently, or pushed by a spring-loaded element.
4. The barrel reaches its extreme front point, compressing the return spring as much as possible.
5. Under the action of the return spring, the barrel begins to move backward, while it picks up a new cartridge from the chamber.
6. The barrel rests against the fixed bolt and the weapon is ready for the next shot.
As is clear from the description, there is nothing difficult to connect the movable barrel with the trigger of the weapon, for its automatic cocking, or to introduce a double-action trigger mechanism. This automation system is quite interesting and simple, but its implementation requires a very precise fit of parts, in particular the barrel and frame, so that the movement of the barrel does not affect the accuracy of the weapon. Naturally, the durability of the weapon will depend on the quality of the materials used, and in this case, in any case, it is subject to very rapid wear. Thus, weapons with such an automation system will need constant lubrication, will be very susceptible to contamination and will not last long, even with the highest quality production. Actually, this was the reason that weapons with such an automation system are very rare.
For the first part of the material on weapon automation systems, I think it will be enough, but there is still a lot of interesting things ahead.
P. S. The first photo is not a suicide club, people are holding ice cream in the form of pistols.
