AK-12. The layout and features of a modern machine
Layout and design features
I am a follower weapons classical layout. Ease of holding when aiming and shooting (especially offhand) and the location of the controls (ergonomics worked out to the ring), versatility in terms of the left / right shoulder, correct balance, convenience when shooting from a stop or through an embrasure, the normal length of the aiming line of a mechanical sight, better compatibility with accessories, etc., are, from my point of view, a more tangible advantage than the absence of the need to fold or recline the bullpup stock from time to time.
The most developed, reliable and, as a result, widespread automation scheme is at the moment a scheme with the removal of part of the powder gases through a side hole in the barrel wall. A variant of this scheme with direct action of gases, when gas from the barrel is fed through the tube into the moving parts, where the shutter works like a piston (all early and most modern AR models, including M16 and M4), despite the high accuracy of fire of weapons made using such a scheme , as well as on the authority, stubbornness and "weight" of manufacturers, is gradually losing ground due to the low reliability of weapons, especially when firing low-quality ammunition. In any case, all new developments of military weapons on this platform are carried out using a gas piston scheme, with its short stroke.
Such a scheme is also used in the SVD rifle, in contrast to the AK series assault rifles, in which the gas piston is installed in the bolt carrier with the possibility of “chattering” relative to it. By no means conducive to improving the accuracy of fire, the “chatter” of a rather massive gas piston is a necessary structural element that makes it possible to ensure the operability of the weapon in case of misalignment of the gas chamber and the gas piston as a result of an unfavorable alignment of the dimensional chain during manufacture and / or barrel leashes as a result of its heating. In the 9A-91 machine gun, which was produced at one time at KMZ, this element was not there, so ensuring the alignment of the gas piston and the gas chamber was a real torment, in spite of any technological equipment.
Is there a gas regulator? To be honest, I'm undecided on this issue. As a designer who has been involved in the creation and improvement of company (unified) machine guns for a long time, I would prefer to have it, especially if the gas chamber still has a front removable plug - a plug. But if you can do without it, and the operating experience of the AK says that it is possible, or the introduction of a gas regulator into the design will greatly complicate it and increase the laboriousness of manufacturing, then probably not.
In principle, the gas regulator, in theory, can increase the accuracy of fire by optimizing the speeds of moving parts in various conditions of use of weapons, but it turns out that if I misjudged these very conditions or they suddenly changed, I can catch a delay at the wrong time. Do I need it? The machine gun has other modes of fire, including the ammunition load fired before cleaning and lubrication, a longer resource - the regulator is definitely needed there, but in the machine gun - I don’t know. Not sure.
The locking units of modern assault rifles (machine guns) are overwhelmingly made with rotary piston valves. In this case, as a rule, three basic designs are used: according to the AK type (AK and Zig-Sauer), AR-10 and 15 (all AR, AUG 77), AR-18 (SCAR, G-36, L-85 and etc.). Kalashnikov locking unit: two or three (SVD) lugs, a helical spiral on the working surfaces of the lugs and the presence of a preliminary rotation of the bolt when locking. Unsurpassed reliability of work is achieved due to the presence of a spiral on the lugs and a preliminary rotation of the bolt when locking, the ability to use a simple and effective rigid reflector, ease of incomplete assembly and disassembly and the absence of small parts. Reflection of the sleeve to the right up.
Among the shortcomings, in comparison with the AR locking units, one can note the rather large dimensions for a given area of the contact patch of the lugs, a large total angle of rotation of the shutter and the moment of inertia when it is rotated, and most importantly, the complexity in manufacturing and the almost (keyword) inevitable need for manual pripilovki and lugs and a cracker or bevel of the shutter, interacting with it, providing a preliminary turn of the shutter. This led to the fact that, except for the Kalashnikov - and the old (with the exception of the Zig-Sauer 556ix) Zigov, this design is not used anywhere, and I have not heard anything about new developments using it.
The locking units of modern assault rifles in the vast majority (just some kind of hegemony) are variants of the AR-10 and AR-15 or AR-18 locking units. The so-called multi-slotted shutters have 7 or 6 lugs, respectively, reflected to the right up or to the right "to the horizon", respectively. The latter is considered a disadvantage in our country, since there is a high risk of a reflected sleeve hitting the face of a nearby person. Whoever thinks that this is a trifle is wrong. But it simplifies the exclusion of contact between the sleeve and the reloading handle, if the latter is installed on the right side of the receiver.
The absence of a preliminary turn of the shutter is sometimes compensated by the introduction of a special locking mechanism into the design, which excludes the possibility of turning the shutter up to a certain point (Kord machine gun), but I have not seen such a mechanism in assault rifles, where this drawback is sometimes partially leveled by a specially selected profile of the copy groove of the shutter frame interacting with the leading part of the shutter.
In terms of the combination of properties for military weapons, the AK locking unit is probably more suitable, especially in terms of reliability. Although the experience of other developers cannot be discounted. At least, the strong advantages of AR-shaped locking units in terms of manufacturability and ease of manufacture and better weight and size characteristics make their use more than justified.
Other advantages of AR locking units, which are relevant both now and in the near future, are the ability to ensure stable manufacturing quality on CNC machines by eliminating the need for manual debugging (sawing). AR locking units are, in principle, better protected from dust and dirt, although they are more sensitive to them and work worse when the barrel chamber is dirty and with substandard ammunition.
Receiver box design
The receiver of a modern assault rifle, you can’t get anywhere, should include mounting brackets for installing existing and future accessories. For an army machine gun, an upper bar of a given length is sufficient, a lower one in the forearm area and, possibly, a short side bar for a lantern.
The benchmark, from my point of view, in this matter are the Czech "Bren", without unnecessary side bars, and the SCAR "Zig-Sauer". Therefore, the use of a breaking or detachable design is by no means a tribute to fashion, but a necessity. In this case, the butt (more precisely, the base of the folding butt) must be rigidly, relative to the barrel, fixed on the upper part of the receiver. The lower Picatinny rail, designed to be attached to an underbarrel grenade launcher, must be made of steel and closed with a forearm in such a way as not to interfere with the shooter when it is not in use.
When using the bar, the forearm must move (but not separate, otherwise it will be lost) in such a way as not to interfere with the use of the bar for its intended purpose. In general, ideally, it is desirable to apply the same solution to the upper bar in the fore-end area with the possibility of covering the machine in the fore-end area with the hand, but this is probably already a technical utopia.
Receiver material: light alloy or sheet steel. Sorry, but I won’t consider plastic, and the point is not only in the epic of the ill-fated G36, but also in the experience of the creators of the AEK (initially, the AEK-971 had a plastic receiver reinforced with steel - the legacy of the Konstantinov and Abakan assault rifles), when shooting two BCs - designated wearable ammunition, there was a delamination of plastic with metal reinforcement of the receiver.
Light alloy boxes have recently received the greatest distribution. They are distinguished, first of all, by high manufacturability and precision in manufacturing, using CNC machines and progressive blanks for their production. At the same time, it is possible to combine several functions in one part, which in stamp-welded structures perform several different parts.
High manufacturing precision and the almost complete absence of permanent connections and complex assembly operations (attachment, for example, of the barrel coupling and some other parts is usually carried out using screws, union nuts, etc. and requires control only by the tightening torque of the threaded connection) virtually eliminates the impact on the quality of manufacturing parts and their assembly of the human factor, but requires a perfect machine park, highly qualified staff and the availability of expensive tools and industrial equipment. A nice bonus of such designs of receivers is their high variability and modernization potential, and equipping the production with perfect equipment determines its flexibility. Of the other advantages of light alloys - a good heat sink.
The disadvantage of light-alloy boxes is the properties of the base material, which has a certain porosity of the structure and low hardness. At one time, Georgy Semyonovich Garanin told me about attempts to use titanium and aluminum for the manufacture of machine-gun receivers. According to him, powder soot immediately and forever "ate" into the material of the parts, increasing the coefficient of friction to completely obscene values, and this obscenity was not amenable to any cleaning. That is, without special galvanic coatings that strengthen the surface structure, the use of such materials is impossible.
It cannot be said that this problem has not been solved. Decided. 70 percent. Congenital defects, like congenital diseases, are almost never completely cured. The coatings have the ability to wear off, are prone to cracking upon impact, i.e., they have some features that require attention during operation. In addition, electroplating is a hazardous industry, and the human factor is again manifested in all its glory there. Characteristics of reagents, their concentration, temperature, exposure time, cleanliness of the bath, sequence of actions, surface preparation. Some of the above parameters do not lend themselves to any automation.
I still remember how they ruined a beautiful horizontal bar brought by someone for repair - ... it takes a long time to warm up the bath to the regimen, the bath is dirty, Masha is on vacation, etc. Somehow I demonstrated a prototype of my experimental 6,7-mm assault self-loading to a soldier who is fond of one of the types (I won’t say more precisely, in my opinion, just an amateur) high-precision long-range shooting and was amazed by his reaction to the aluminum Picatinny rail made integral with the receiver. He clung to it from the fly, not paying attention to the actual weapon, the meaning of his claims was that such things should be made only from steel, and light alloy has poor wear resistance. Well, imagine army operation - in armored vehicles, in mountainous areas or in an urban environment.
Combined steel-aluminum structures are an electrochemical pair and need to be protected from corrosion, in addition, they have very different coefficients of thermal expansion, and their joint assembly can turn into some design and technological problem (you can hardly apply both spot and any other welding, and you can’t put a rivet without a futorka). The labor intensity of manufacturing and the dependence on the human factor are increasing, and some specific problems appear.
I mentioned above about steel receivers of a stamp-welded design, and I have nothing to add in essence. They are better than any others for military operation, cheaper for mass production, but their use makes sense only if there is confidence in the longevity and decent production volumes of this type of small arms.
That is, the design of a promising assault rifle depends on the specification (primarily), the design of the accessories declared for use, the available technologies of a particular developer, the capabilities of its intellectual design and technological resource, the available backlog (after all, it’s not for nothing that the Kalashnikov concern always gets another AK - already 75 years, and AEK for 40 years of development has changed externally, but not internally, only because of the requirement to add a bar - little things do not count) and some non-production factors. In other words, any developer, instead of a design optimized for the requirements of the TOR he received, will strive to use his backlog, try to adjust and harmonize the TOR for it, etc.
People can be understood, technical risks and the associated responsibility are not needed by anyone. Start somewhere from scratch? And where in this blank notebook can I get the appropriate frames? Promising youth? But this is just material for learning - a reserve for the future. Only constant training and their own experience, which still needs to be gained, can make them specialists (and even then not all of them), but it is still desirable to learn from the mistakes of others, but they still won’t get away from their own. And for training, experienced specialists are required who can design “from a sheet”, and not just assemble pyramids from ready-made cubes. But for some reason, as a rule, they interfere with modern experienced "menagers". In addition, the issue of licensing, testing and other organizational components of the infrastructure necessary for engaging in this kind of activity arises.
I would like to mention once again the design of accessories. Well, if you develop them for new requirements, then it is desirable to develop all accessories for these requirements, and not: this new one with a universal installation on a bar and, say, a grenade launcher - from AK and an installation place, please, do it like an AK. This rigidly dictates the configuration and dimensions of many parts of the weapon, and its architecture as a whole. For sights, flashlights, etc., it is necessary to develop a quick-release mount on the Picatinny rail, similar to what is currently used for mounting on a standard side rail. And, finally, the cartridge, which must be decided not least.
In fact, I will not make a discovery from the assertion that in order to replace such a product as an AK assault rifle (I believe that today it is still the best military assault rifle in the world for our conditions), an integrated approach is needed with carefully thought-out technical specifications and, possibly, , with intermediate R&D to test some solutions.
Forgive me if you will. Of course, I don’t know all the layouts, but it became strange for me to observe what was happening, and in fact, by and large, there is a clearly visible trend of losing our country’s position as one of the main world authorities in the development and production of small arms. It still somehow makes a difference to me, and I think that we should at least talk about it.
And as for the deeply substantiated conclusions of some especially advanced experts that in the age of missile weapons and aviation small arms are losing their relevance, let them try to find at least one example when military operations were carried out without the use of this “anachronism”, but the Taliban, for example, completely managed without missiles and aircraft.
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