PSS silent pistol

The PSS silent pistol or MSS "Vul" ("Вул") is the last completed weapon system resulting from the Soviet development of silent pistols operating on a sealed cartridge system. Two previous designs were considered unacceptable for use due to their limitation to two shots. Earlier systems included the MSP and SP-4M double barreled pistols. Developed around 1980 for assassinations and reconnaissance, the PSS was first issued to KGB Spetsnaz in 1983. It is under production in the special weapons foundry at TsNIITochMash. PSS pistols are still in use by elite special forces units of many nations and by some FSB and MVD units.
The original PSS was succeeded by the PSS-2 in 2011, using the more powerful silent 7.62×43 mm SP-16 cartridge.
Purpose.
The PSS was developed to give Soviet special forces and secret police an almost completely silent option for covert operations such as reconnaissance and assassinations. The weapon uses a special cartridge with an internal piston to achieve this goal. Otherwise, it is a fairly simple double-action pistol. Few details are known about the pistol's performance, as only a few have entered Western hands.
Operation.
Cartridge.
The PSS uses a specially-developed 7.62×41mm necked round SP-4 (СП-4), also used by the OTs-38 Stechkin silent revolver. The cartridge contains a propelling charge which drives an internal piston in contact with the base of the bullet. On firing, the piston propels the bullet out of the barrel with enough energy to achieve an effective range of 25 meters. At the end of its travel the piston seals the cartridge neck, preventing noise, smoke, or blast from escaping.
Action.
The PSS is recoil-operated. It has a slide designed to operate silently, in keeping with the pistol's design for silent operation. In other respects the PSS generally follows traditional conventions, except for the slide's guide rod, which is located above the barrel and instead of guide rails on the pistol frame.
Variants.
The PSS-2 silenced pistol was developed in Russia, based on the original PSS but with some features of the SR-1M pistol and some improvements. It fires SP-16 noiseless 7.62x43 mm ammunition, more powerful than, but incompatible with, the original 7.62×41 mm cartridge. The PSS-2 was adopted by the Russian FSB security agency in 2011.