The Stechkin automatic pistol was adopted by the Soviet military in 1951, alongside the Makarov pistol. Both are chambered bot the 9x18mm Russian cartridge, and both use simple blowback mechanisms. The Stechkin is a heavier and bulkier pistol, though, as it is designed for fully automatic fire.
The Stechkin uses a 20-round magazine as standard, and has a selector switch allowing single shots or automatic. It was originally issued with a combination shoulder stock/holster (much like the Mauser 1896) to allow more precise shooting, and was supplied to support troops like tankers, RPG carriers, and artillerymen. It became apparent, however, that a machine pistol was not a particularly practical weapon, and the Stechkin was slowly withdrawn from use. The weapon received a bit of new life in the 70s, when some existing stocks were updated for Spetsnaz use, with the addition of sire stocks, threaded barrels, and sound suppressors.
Manuals
Stechkin APS manual, printed 1960 (Russian)
Engish translation of 1960 Russian Stechkin manual
Photos
From Max Popenker, we have a couple photos of a Stechkin APS with stock and suppressor (click to download gallery in hi-res):
I’ve had the opportunity to dig into one of the few APS’s here in the U.S..
Interesting design. Notable is the considerable overtravel exhibited by the slide, likely to assist in reducing the ROF.
Handling and firing was not unusual, in semi they are immensely comfortable, and even in FA, sans stock if one adopts a firm Weaver stance they are not at all as uncontrollable as one would expect.