YouTube Video: APS (Stechkin Machine Pistol)

The Stechkin APS (Avtomaticheskiy Pistolet Stetchkina, Russian: Автоматический Пистолет Стечкина) is a Russian selective fire machine pistol. It bears the name of its developer, Igor Stechkin.
The Stechkin pistol was originally chambered for 7.62x25mm Tokarev. Circa 1961 - 1975.
Stechkin changed the pistol to the 9 mm caliber used in the new Makarov pistol, as it became clear that this cartridge was set to become the new service ammunition for handguns of the Red Army.
In 1951, both the Makarov and Stechkin were introduced into the Soviet military arsenal, replacing the trusted Tokarev TT-33. They do not only look similar but have indeed much in common, such as the simple unlocked blow-back mechanism.
In contrast to the Makarov, the Stechkin APS has an automatic fire mode, which is selected using the safety lever. In burst or automatic fire, the pistol should be fitted with the wooden shoulder stock; otherwise, the weapon quickly becomes uncontrollable. The detachable stock is similar in appearance and design to that of the Mauser C96, and likewise, the pistol can be stored inside when not in use. The extra weight of the stock helps to control the recoil.