In 1960s the US Army adopted a new round, caliber 5.56x45 mm. Considering this a serious challenge, the Soviets could not but react accordingly. A novel round of 5.45x39 mm was supposed to be an antipode to the American 5.56 cartridge.
In 1965 - 1966 TSNII TOCHMASH, Russian leading institution in small arms research, outlined new principles of enhancing effectiveness of automatic weapons by means of the so-called balanced automatics. Preliminary experiments revealed that the experimental low-impulse cartridge in caliber 5.45x39 mm round might be a perfect challenge to the 7.62x39 mm, model 1943, unitarian intermediate round. Army experts believed that the new "weapon + round" complex would pave the way toward a new generation of infantry small arms.
The then Soviet military wanted to create a weapon, which would be lighter but more effective than the issue, thus making assault rifles in their classical notion outdated and absolete conceptually. A contest was declared. Izhmash and the Kovrov Arsenal accepted the challenge.
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Izhmash commissioned, a young and promising arms designer. He was appointed as a project engineer to do the job. The Kovrov design bureau had Alexander Konstantinov as a participant of the contest. The army wanted to have the weapon as simple and as reliable as the AK47 assault rifle, but with substantially better performance capabilities, accuracy in particular. For this reason, they recommended that AKM be taken as a basic model for this experiment. Izhmash made an attempt to not only adapt the well-fielded firearm to the new ammunition but also to improve its construction by creating a mechanism of decreasing the muzzle jump, by substantially enhancing controllability and hit probability of the weapon. created a series of experimental rifles, two of them being (Avtomat Lehkiy stands for "light assault rifle") turned out a serious and a tough competition. This version had a laminated handguard, a non-folding buttstock, and an orange plastic 30-rd detachable, like the AKM assault rifle. Alexandrov says, his basic weapon was designed in 1969. Experimental and research works, however, were still going on for a few years more. Finally, the weapon successfully passed all tests, and the project was completed by May 22, 1972.
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At that period and his team were about to complete modernization of the AKM assault rifle, adapting it to the 5.45x39 mm cartridge. "To be or not to be" - which of the weapons, AL-7 would get the upper hand with the military, was a tough question.
The results of an extensive experimentation revealed that the technical doctrine of the balanced automatic mechanics would require substantial capital investments for the factories to change their production lines. The ailing Soviet economy could not afford such a heavy financial burden. Further financing of the program became a problem. Finally, developments and research on the AK-type small arms lead to a compromise between the economic factors and the effectiveness of the weapon.
Thus the AK-74 and its modifications were accepted for service. In the late 1970s and 1980s the ABAKAN program got everybody's attention. This contest resulted in creation of the futuristic "leap-ahead" AN-94 assault rifle, and the idea of the balanced automatics was abandoned. But only temporarily.
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AK in this case stands for Alexandrov + Kalashnikov.
| AK-107 | AK-108 | |
|---|---|---|
| Caliber: | 5.45 | 5.56 |
| Cartridge: | 5.45x39 | 5.56x45 |
| Operation: | Semiautomatic, burst of 3 rounds and full-auto fire modes. Fire from the closed-bolt position. |
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| Cyclic rate: | 850 to 900 rpm | |
| Sighted range of fire: | 1,000 m | |
| Feed: | Fiberglass-reinforced polyamide 30-round box-type detachable magazine. |
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| Weight, empty without mag.: | 3.6 kg. | |
| Weight of magazine, empty: | 0.20 kg. | |
| Length, overall: | 943 mm | |
| Length, with buttstock folded: | 695 mm | |
| Barrel: | Four-grooves, with right-hand twist of one turn in 200 mm (AK-107) and 178 mm (AK-108). |
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| Barrel length: | 415 mm. | |
| Sights: | Sliding tangent-type rear sight with U-notch. Round, post-type front sight with protective ears; adjustable for windage and elevation zero. |
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| Finish: | Black phosphate. | |
| Furniture: | Black fiberglass-reinforced polyamide pistol grip. |
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| Muzzle velocity: | 900 m/sec | 910 m/sec |
| Weight of round: | 10.2 g | 12.5 g |
| Weight of bullet: | 3.42 g | 4.5 g |
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As seen from the photos, the AK-107 and AK-108 Assault Rifles have minor
cosmetic differences compared to standard AK100-series.
The top cover is fixed to the receiver by means of a lever on its rear end.
The geometry of case ejection opening looks slightly differently from the
one in the original AK weapons. The steel cover of gas chamber extends from
the top handguard to the front sight block.
The bolt, the construction of trigger mechanism, receiver, fire mode
selector, front sight, the stock, magazine and muzzle brake are identical
with the AK-family weapons.
The basic difference between AK-107/108 and original AK is the availability
of counter-balancing synchronizer with a six-tooth sprocket.
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The principles of operation of the AK-107/108 weapons are based on the utilization of energy of propellant combustion gases diverted from the barrel into the gas chamber through the side opening in the barrel. In order to reduce negative effect of the shock of bolt carrier in its front and rear positions, the carrier features a connecting rod in the form of a perforated lower rail. The latter is synchronized with the upper rail by means of a six-tooth sprocket. When a round is fired and the gas escapes into the gas cylinder to activate the two pistons of the upper rail and that of bolt carrier, the bolt carrier rolls into its rear position while the upper rail travels into its front position. The two dead points are reached by two inertia masses simultaneously, thus reducing recoil shock thanks to the synchronizing effect of the sprocket.
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When the selector comes one step below into position marked "3", the rifle fires 3-round bursts. This possibility is provided by the special ratchet-and-paw device available on the selector axle. The ratchet has three teeth. When so placed, the rifle fires three successive shots, while the bolt carrier interacts with the ratchet. Each time the bolt approaches and
pushes the device, the latter is turned to the value of the tooth's module and retained in such position. As soon as the last of the three rounds is fired and the ratchet comes into extreme rear, it is automatically released to resume its initial position. The sear retains the hammer. The round is locked in the barrel. To resume the next 3-round cycle, the trigger should be released and depressed again. The hammer releases from the sear to rush forward and strike upon the firing pin. The first shot of the next 3-round burst is delivered.
If the selector is in the extreme lower position marked "1" (single fire, semiautomatic mode) and the trigger is depressed, the weapon delivers only
one shot. In order to repeat the cycle, the operator has to repeatedly release and depress the trigger.
The author found that the average accuracy (fire in a standing position without support) of both AK-107 and AK-108 is by 1.5 - 2.0 times better than that of standard AK100-series firing similar types of ammunition.
