9A-91 compact assault rifle (Russia) 

Caliber: 9x39 mm 
Action: Gas operated, rotating bolt
Overall length: 605 mm with open butt, 383 mm with folded butt
Barrel length: ?? 
Weight: 2.1 kg empty 
Rate of fire: 600-800 rounds per minute 
Magazine capacity: 20 rounds 

The 9A91 9 mm compact assault rifle was originally developed as a part of the A91 family of compact weapons, which included versions chambered for 7.62 x 39, 5.45 x 39, 9 x 39 and 5.56 x 45 ammunition. Of those, only the 9 mm version survived and entered small-scale production at the Tula Arms Factory in 1994. Designed by the famous KBP design bureau in Tula, the 9A91 was originally intended for an Army PDW (Personal Defense Weapon) role, but instead found some favor in the ranks of MVD and Russian police troops, as a less expensive equivalent of the SR-3 "Vikhr" compact assault rifle. The 9A91 also served as a basis for a silenced "para-sniper" weapon, the VSK-94, also chambered for 9 x 39 ammunition.

The 9A91 is a gas operated, rotating bolt weapon, which utilizes a long stroke gas piston, located above the barrel, and a rotating bolt with 4 lugs. The receiver is made from steel stampings; the forend and pistol grip are made from polymer. The steel buttstock folds up and above the receiver when not in use. The charging handle is welded to the right side of bolt carrier. The safety / fire selector lever is located at the left side of the receiver, above the trigger guard, and allows for single shots and full automatic fire. The flip-up rear sight has settings for 100 and 200 meters range, but the relatively short sight base and steep trajectory of the subsonic bullet effectively restricts the 9A91 to ranges of about 100 meters, at which the 9 x 39 ammunition is clearly superior in penetration and hitting power to either 9mm pistol ammunition from submachine guns, or 5.45 and 5.56 mm ammunition from compact assault rifles like AKS-74U or HK-53.

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