OTs-33 "Pernach" (pernach = multivaned mace) is a recent entry into the small and very special class of automatic (machine) pistols, and is intended to replace obsolete Stechkin APS pistols in the hands of various special units in Russian police and other paramilitary units. Developed circa 1995-96 by the Igor Stechkin at the TSKIB SOO (central design bureau for sporting and hunting arms, Tula, Russia), the same designer who developed the APS, the OTs-33 is now in limited production by the KBP design bureau. OTs-33 has simplified "squared" shape and is much easier (and less expensive) to manufacture, as well as simpler in design. It is capable of fully automatic and semi-automatic fire, and can be fitted with detachable folding shoulder stock, made of steel. It is in limited use with some OMON units in Russian police.
OTs-33 is a blowback operated, selective fire weapon. While there's no positive lock between the slide and barrel, the barrel is allowed to recoil in the frame for a short distance. As the gun is fired, the slide recoils back, and at the final stage of recoil it hits the barrel and carries it back. The additional weigh of the barrel helps to slow down the slide and thus decrease the felt recoil and the cyclic rate of fire without the complicated rate reducer, found in APS pistol. The OTs-33 has double action trigger with exposed hammer. The ambidextrous slide mounted safety / fire mode selector has thee positions, for safe (top), single shots (middle) and full automatic mode (down). When the safety/selector lever is pulled above the "save" position, it safely de-cocks the hammer and then returns to safe position. The ambidextrous lever inside the triggerguard, just ahead of the trigger, is used to disassemble the pistol (unload pistol, pull lever down, then remove the barrel/slide assembly). OTs-33 is fed using double column magazines with capacity of 18 (standard) or 27 (optional) rounds. The OTs-33 frame has integral accessory rails under the barrel for tactical lights or laser pointers. Frontal parts of the barrel and slide are ported to act as a muzzle jump compensator. Fixed sights have white inserts for improved visibility. OTs-33 is issued with leather holster with separate magazine pouches and a shoulder stock pouch.