The SR-2 (Russian: СР-2; standing for "специальная разработка 2", Spetsialnaya Razrabotka 2, lit. "Special Development 2"), codenamed Veresk (Russian: Вереск; literally "heather") is a Russian submachine gun firing the 9x21mm SP-10 (SP stands for Spetsialnyj Patron, lit. "special cartridge") armor-piercing ammunition (also known as the 9x21mm Gyurza) originally designed for the SR-1 Vector pistol. It is a gas operated submachine gun, using a scaled-down version of the action in the SR-3 Vikhr compact assault rifle. It can use 20- and 30-round magazines.
There are three variants of the SR-2:
SR-2, the original variant.
SR-2M, the modernized variant with a folding front grip and redesigned muzzle.
SR-2MP, the improved variant of the SR-2M featuring Picatinny rails and the ability to install suppressors as well as an alternate buttstock.
