The AEK-971 Assault Rifle emerged from the Kovrov Mechanical Plant (KMZ) during the 1980s with design work having begun the decade prior. At its core the weapon became a traditional automatic weapon system firing the usual array of Soviet standard cartridges through a gas-operated, rotating bolt action. Its form and function were similar to the classic Kalashnikov family of rifles and included the over-barrel gas cylinder as well as the curved, detachable box magazine. Where the AEK-971 differed was in its use of the BARS action - "Balanced Automatics Recoil System" - which has proven to increase shooter accuracy in successive fire (i.e. burst fire, full-automatic fire) by reducing the effects of recoil. In the BARS system, the recoil effects are moved closer to the muzzle and a rearward action of the bolt and bolt-carrier help to further minimize the effects of "muzzle climb".
The AEK-971 was one of several firearms entered into a competition to find the next standardized Soviet Army rifle and this included the competing AN-94 detailed elsewhere on this site. The rifle was eventually adopted, though in limited numbers, and issued to various elements of the Soviet Navy and federal forces but little else in terms of reach has been seen of this design - it did manage to see combat service in the Second Chechen War with Russian forces. The AN-94, despite being heavier and more expensive to manufacture, won out over the AEK-971 in the long run.
Nevertheless there still remained support for the AEK-971 design which has managed to stay in the fold and deliver several related variants and subvariants. AEK-971 became the primary variant of the family, chambered for the 5.45x39mm cartridge, while the AEK-972 was chambered for the 5.56x45mm NATO cartridge favored by the West. This led to a slight variation in the curvature of the magazine. The AEK-973 was the third in the series and chambered for the 7.62x39mm rifle cartridge which gave better penetration at range. The AEK-971 and AEK-973 then begat subvariants all their own, these becoming the improved AEK-971S and AEK-973S (respectively) forms. The pair used an all-new trigger system, three-round burst fire mode, and lighter-weight shoulder stocks.
More modern incarnations of the AEK-971 are the A-545 and A-762. As their designations suggest, these models are chambered for the 5.45x39mm and 7.62x39mm cartridges respectively. The A-545 is actively competing against the AK-12 model as both remain in limited service for evaluation purposes. The A-545 is considered the direct successor to the earlier AEK-971 line.