The AK-74 (Russian: Автомат Калашникова образца 1974 года or "Kalashnikov automatic rifle model 1974") is a 5.45mm assault rifle developed in the early 1970s in the Soviet Union. It was developed from the earlier AKM (itself a refined version of the AK-47) and introduced in 1974.
The rifle first saw service with Soviet forces engaged in the Afghanistan conflict. Presently, the rifle continues to be used by the majority of countries of the former USSR. Additionally, unlicensed copies were produced in Bulgaria (AK-74 and AKS-74U), the former East Germany (MPi-AK-74N, MPi-AKS-74N, MPi-AKS-74NK) and Romania (PA md. 86). Beside former Soviet republics and eastern European countries, Mongolia, North Korean Special Forces, and Vietnamese People's Naval infantry use AK-74s.
The AK-74 is an adaptation of the 7.62mm AKM assault rifle and features several important design improvements. These modifications were primarily the result of converting the rifle to the intermediate-caliber 5.45x39mm cartridge, in fact, some early models are reported to have been converted AKMs, with the barrel re-sleeved to 5.45x39mm. The result is a more accurate and reliable rifle than the AKM. The AK-74 and AKM share an approximate 50% parts commonality (interchangeable most often are pins, springs and screws).
The rifle’s operation during firing and reloading is identical to that of the AKM. After ignition of the cartridge primer and propellant, rapidly expanding exhaust gases are diverted into the gas cylinder above the barrel through a vent near the muzzle. The build-up of gases inside the gas cylinder drives the long-stroke piston and bolt carrier rearward and a cam guide machined into the underside of the bolt carrier along with an ejector spur on the bolt carrier rail guide, rotates the bolt approximately 35° and unlocks it from the barrel extension via a camming pin on the bolt. The moving assembly has about 5.5 mm (0.2 in) of free travel which creates a delay between the initial recoil impulse of the piston and the bolt unlocking sequence, allowing gas pressures to drop to a safe level before the seal between the chamber and the bolt is broken. Like previous Kalashnikov-pattern rifles, the AK-74 does not have a gas valve; excess gases are ventilated through a series of radial ports in the gas cylinder. Since the Kalashnikov operating system offers no primary extraction upon bolt rotation, the AK-74 bolt has a larger extractor claw than the 7.62mm AKM for increased extraction reliability. Other minor modifications were made to the bolt and carrier assembly.
The rifle received a new barrel with a chrome-lined bore and 4 right-hand grooves at a 200 mm (1:8 in) rifling twist rate. The front sight base and gas block were redesigned. The gas block contains a gas channel that is installed at a 90° angle in relation to the bore axis. A pair of support brackets are cast into the gas block assembly and are used to attach a BG-15 or GP-25 under-slung 40 mm grenade launcher. The forward section of the front sight base features a threaded collar that is used to screw in a newly-designed multifunction muzzle device (performing the role of a muzzle brake, recoil compensator and flash suppressor) or a blank-firing adaptor. The muzzle device is held in place by a spring-loaded button and is quickly detachable. The distinctive muzzle brake features a large expansion chamber, two symmetrical vertical cuts at the forward end of the brake and three vent holes positioned to prevent muzzle climb and lateral shift to the right (for right-handed shooters). A flat plate near the end of the brake produces a forward thrust when emerging exhaust gases strike its surface, eliminating nearly all felt recoil. The muzzle brake prevents backblast from reaching the firer, although it is reported to be harsh on bystanders as the muzzle gases are dispersed to the sides.
The AK-74 was equipped with a new stock, handguard (which retained the AKM-type finger swells) and gas cylinder. The stock has a different shoulder pad than the AKM, which is rubber and serrated for increased traction. In addition, there are weight-reducing lightening cuts on each side of the buttstock. These also function to distinguish externally by sight and touch between the AKM and the AK-74, preventing the accidental loading of the wrong ammunition in the AK-74. The stock, lower handguard and upper heatguard were first manufactured from laminated wood, this later changed to a synthetic plum and then a black-colored polymer.
The AK-74 gas tube has a spring washer attached to its rear end designed to retain the gas tube more securely. The lower handguard is fitted with a leaf spring that reduces play in the rifle's lateral axis by keeping the wood tensioned between the receiver and the handguard retainer. The receiver remains nearly identical to that of the AKM; it is a 1 mm (0.04 in) thick sheet steel pressing supported extensively by pins and rivets. The internal guide rails on which the bolt carrier travels are stamped and spot welded to the inside of the receiver housing. Minor changes were made to the front barrel and rear stock trunnions as well as the magazine well. All external metal surfaces are coated with a glossy black enamel.
The original AK-74 magazine was identical to that of the AKM, except for minor dimensional changes required by the 5.45x39mm cartridge. These rust-colored magazines are often mistakenly identified as being made of Bakelite (a phenolic resin), where in reality, they were fabricated from a two-part glass-reinforced polyethylene plastic molding, assembled using an epoxy resin adhesive. Noted for their durability, the magazines did however compromise the rifle's camouflage. A new dark-brown (newer magazines are black) 30-round magazine was introduced in the early 1980s, composed of ABS plastic. All AK-74 magazines have a raised horizontal rib on each side of the rear lug to prevent their use in a 7.62x39mm AK. The magazines can be quickly recharged from stripper clips. The 45-round plastic magazine of the RPK-74 light machine gun is also interchangeable with that of the AK-74.
Accessories supplied with the rifle include a 6H4 or 6H5 type bayonet, a quick-loading device, three spare magazines, four 15-round stripper clips, maintenance kit, cleaning rod and sling. The bayonet is installed by slipping the muzzle ring around the flash hider and latching the handle down on the bayonet lug under the front sight base. The rifle fires the intermediate 5.45x39mm M74 rifle ammunition that includes the jacketed, steel-core 7N6 bullet, 7T3 tracer round and a blank cartridge. The ammunition was developed by a team of designers led by Victor Sabelnikov.