AK-107 / AK-108 animation

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It has been a while since I have posted an animation. This one, author unknown, shows how the balanced gas operating system works in the AK-107 and AK-108 rifles.

Ak 107 108-3
( If the animation is not playing, try this link: click here)

Wikipedia explains how the system works:

The AK-107 and AK-108 represent a significant change to the Kalashnikov operating system originally designed in the late 1940s. The new rifle features a balanced system that functions along the lines of Newton’s third law of motion, which states that for every action there is an equal and opposite reaction. This system uses a recoil-dampening countermass mechanism with two operating rods that move in opposite directions, thereby providing “balance”. One operating rod, the upper, has a gas piston facing forward while the bolt carrier also has a gas piston. The gas tube at the forward end of the handguard is double-ended to accommodate the two rods. The enlarged gas tube cover of the upper handguard guides both rods in their travel.

When the rifle is fired, gas is tapped from the gas port to enter the gas tube, driving the bolt carrier to the rear and the counter-recoil upper rail forward. The critical timing of the reciprocating parts is accomplished by a star-shaped sprocket that links and synchronizes both components, causing both to reach their maximum extension, or null point where forces are exactly equal, at exactly the same instant. The felt recoil is therefore eliminated, enhancing accuracy and assisting control during fully automatic fire. The travel distance of the AK-107 reciprocating parts is less than other Kalashnikov designs, so the cyclic rate is higher at 850–900 rounds/min rather than 600 rounds/min on other AK rifles. However, as the felt recoil is virtually eliminated, the manufacturer claims that accuracy is enhanced, especially during burst fire. An enhancement of 1.5 to 2 times has been reported.

The system was previously used on the prototype AL-7 and AEK-971 rifles in the 1970s.

Hat Tip: fuliginosus @ guns.reddit.com


Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


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  • Jesse

    That’s amazing. I wonder if this will improve accuracy because a large part of the reason that the AK is less accurate has to do with the recoiling mass of the piston.

  • http://emptormaven.com EmptorMaven

    That is a very cool design! Are there any balanced piston actions available in the U.S.?

    • Hannibal

      Redhat on Sons of Guns combined an AK gas assembly with a hydraulic action with a M4 lower receiver and a 5.56 barrel. The result is an M4/AK hybrid that doesn’t jam when dragged through Nevada sand or dunked in a tub full of water, yet fires on full auto with the speed of an M4. Forget this 107.

      Redhat has a brand new assault rifle out there that is the best of both rifles and it performs amazingly well. So well in fact, that U.S. nuclear facility security forces are going purchase thousands of these from Redhat.

  • Vitor

    Really cool mechanism, and actually looks quite simple.

  • Brandon

    Hmm, scratching my head on this one. I’m usually pretty keen on physics so in my estimation “recoil free” is not true here. With newtons laws accounted for the reciprocating bolt is balanced by the reciprocating rod, but that still leaves one opposite reaction for the bullet. Since this is a gas operated gun not a recoil operated gun where has the recoil gone for the bullet?

    No I haven’t shot one, maybe they are recoil free. This is just a physics inquiry for those who may know a lot more about what goes on under the hoo…err… furniture in this rifle than is apparent by the animation up there.

  • Jay

    Excellent animation. Descriptions of how a mechanism works are always good, however sometimes the addition of an animation helps smooth things out a bit… I’ve never seen one for the 107/108 before. Thanks!

  • Jacob

    It`d be cool to see a AR-15 model with the balanced system. A modded HK416 perhaps?

  • Bram

    I thought that the purpose was to eliminate climb – not recoil. Of course they are related – your shoulder gets shoved back hard, the muzzle is going to head skyward.

    But get that reduced recoil going straight back with the counter weight at the end of the barrel and you have a chance of keeping the sights on target.

  • hga

    This can’t be “recoil free”. The bullet and gas behind it cannot be counteracted by any contraption of moving parts in what’s left behind.

    Which doesn’t mean that this design can’t be ergonomically more friendly than the original (beyond improving on the problem of the moving piston), just that it can’t negate Newton’s Third Law.

    • http://www.thefirearmblog.com Steve

      you are right, it cannon eliminate recoil, it it built to reduce the effect movement of the bolt on accuracy.

  • jgon281

    I have an Ak-107 F from Arsenal . I have never fired an Ak previous to firing mine so I can’t say if it has less recoil or not. I can say that it is not what I expected . My first thought was that I’d better prepare for a good kick but it didn’t happen . It was very similar to firing my AR with a tad more ummff. A very pleased owner here.

  • jgon281

    disregard my comment . I have a different rifle than the russian Ak .

  • Brad

    I don’t know anything more about the AK-107 than what is contained in the story, but I see how the counter-mass could function to reduce recoil from firing the cartridge.

    Just because the counter-mass/gas-piston is synchronized with the bolt-carrier/gas-piston doesn’t mean the counter-mass is equal to the bolt-carrier. Perhaps the gas-port for the counter-mass is much larger (and operating spring much stiffer) than that for the bolt-carrier. There might be much more momentum in the counter-mass than in the bolt-carrier.

    But even if the AK-107 functions as advertised the tactical concept of hand-held full-auto fire for every infantryman seems like an idea whose time has come and gone. A mixed squad combining accurate semi-automatic fire provided by well trained infantry using accurate rifles with optical sights plus volume fire from a dedicated squad-automatic weapon seems like the wave of the future now.

  • comatus

    I suppose everyone here would know it already, but there are similar mechanisms in high grade air rifles. It’s why an Anschutz target air rifle costs more than an Anschutz target smallbore: more parts.

  • MattCFII

    If you want to see a similar Russian development look into the An-94 as well. The AK-107/108 should be more reliable than the AN-94 because it uses cables and pulleys IIRC. One other piece of cool AK-107/108 trivia is that it has 3 round burst, full, and semi. I still don’t think that the newer system is as reliable as a standard AK but interesting.

    Yes their is still going to be a recoil force back but Netwon’s 3rd still applies the forward force of the counter weight which is timed to counter the recoil at the same time reducing the resultant rearward force of the recoil impluse.

  • jdun1911

    A good muzzle break and free floating barrel is far better then this complicated system.

  • Vitor

    Complicated? I didnt find it so.

  • jdun1911

    Mechanically it is complicated for a rifle. AR15 is simpler then the standard Kalashnikov because the piston on the AR15 is part of the bolt. So you have one less moving part to deal with and hence greater accuracy and lighter weight.

    The AK107/108 has an extra piston, spring, and a wheel from the looks of the animation. That’s three extra moving parts that can fail. It add unneeded weight and complexity for what? Lower muzzle climb and better accuracy? You can do it with a free floating handguard and a good muzzle break.

    The AK 107/108 like the AN-94 isn’t going anywhere.

    AR15 accuracy:
    http://www.ar15.com/forums/topic.html?b=3&f=118&t=414599&sr=0

    How the Piston in your DI AR works
    http://www.ar15.com/forums/topic.html?b=2&f=130&t=165511

  • http://ridenshoot.blogspot.com Ride Fast

    [...] AK-107 / AK-108 dual gas system [...]

  • mike

    i think its a better system than , every time you fire the bullet craps into the receiver , this system is very effective look it up its on youtube. if they made a 308 or 762.54r with this system in a saw config. they would dominate. the NEW 416 that everybody is suckin on is really nice but isn’t it just a gas piston like the ak? hmmm maybe those darn russians were onto somethin! they have less red tape and are very interested in infantry small arms and the mythical FREE floated barrel and muzzle brake don’t really compare to this system you can throw all types of crap on your fake m4 but it will never be as good or advanced as this, the m4 is not even close to being as reliable as this system you cannot take a handful of ammo from 7 different countries load it into a clip and fire . it will NOT work i bet u my check on it . you can fire the 762.39 on full auto and the weapon barely moves ?? its a very good system

  • mike

    well i checked and couldn find it easily on youtube i was thinking of the aek which similar and had them all mixed up

  • Steven

    To everyone who thinks this is a complicated/unreliable system. First I am going to explain that this system only works on 1 spring, not 2. The recoil spring is in the exact same place as on a normal AK rifle. The Pinion wheel returns the forward gas piston, not a spring. The forward gas piston is essentially a free-floating part. If you study these images…

    http://world.guns.ru/assault/as07-e.htm

    …you will find that there are only 2 or 3 more parts than a standard AK, and field stripping is just as easily done.

    Aslo, nowhere in this article were the words “Recoiless” or “Recoil Free”. The counter-mass’ only purpose is to dampen the blow-back of the bolt-carrier, and to keep the muzzle down as a result of the force vector from the recoil spring and shoulder collisions. To sum it all up, the only collision that is canceled in the entire mechanical operation is the recoil-spring and shoulder. The explosive force of the cartridge is the only felt recoil of the weapon, which is actually less force that the recoil spring using the receiver and your shoulder as a backstop in order to return forward.

    Also the force vector from the explosion is exactly perpendicular to your shoulder as you fire the weapon. The force vector of the recoil-spring is actually offset above your shoulder which is ultimately what causes the muzzle to climb. So it should be clear to anyone that just the reduction/cancellation of the recoil-spring’s force alone, is enough to improve a weapons accuracy incredibly.

  • Jim

    I can’t believe this! I invented this design (the countervailing weight used to reduce recoil by borrowing some of the explosive force of the round which also actuates the bolt) just a few months ago! All of my best ideas get put into production long before I can even develop them. Not saying that they were stolen, but damn is it unfortunate that great minds think alike.

    Oh well, back to the drawing board.

  • Dave

    For those of you wondering whether the AK-107 is recoil free, IT IS NOT RECOIL FREE BUT THE AK-107/108 AND AEK-971 SURPASSES ALL OTHER ASSAULT RIFLES ON FULL AUTOMATIC (AN-94 is more accurate on 2 round burst than the AK-107/108 and AEK-971). The balanced action cancels the recoil generated by the movement of the bolt carrier. Also, the AK-107/108 has a muzzle brake similar to that of the AK-74. Given the fact that an AK-74 has about half the recoil of the M16 due to the muzzle brake, you can imagine how good the AK-107 is. The muzzle brake alone drops recoil to about half that of the M16 plus recoil generated by the movement from the bolt carrier is eliminated. The AK-107 has very “soft recoil” and is 15-20% more accurate on full automatic when compared to AK-74. Direct impingement sucks, AK-107 balanced action is way better.

  • http://russianmilitaryphotos.wordpress.com/ Lorenzo

    The AK-107 is not “revolutionary” enough to replace the AK-74M, so don’t expect to see too many of these (if any) in service anytime soon.

  • Lemming

    Always loved this rifle, and with the new rails and sights this gun seems almost perfect. Just improve the ergonomics like they did on the AK-12 and this will be an orgasmic weapon. I really wish the Russian military would open their eyes and stop being so conservative. This rifle has the potential to be the very best out there.

  • Sven

    Reakce zpětného rázu zůstává celá zachována, pouze je pomocí ozubeného pastorku, který je součástí pouzdra zbraně, rozložena do mnohem delšího časového úseku, než u klasických zbraní.

    Sorry my english:
    Reaction of recoil stay full, only by help of teeth wheel, which is solid component of cascet weapon is this force unfold to very longer time interval, against classic weapons.

  • Sven

    Lépe řečeno :
    Zpětný ráz je stejný jako u klasického AK (do okamžiku odemčení), kdy projektil přeběhne piston. Dále platí předešlý příspěvek.

    Better say :
    Recoil is the same how has classic AK ( to time unlock ), when projectile run acros the piston. After is valid previous report.