Unusual weapons is a series of posts about weapons with rare and interesting design solutions.
PSS silent pistol is Soviet pistol which uses sealed cartridges in order to achieve silent shooting without using a silencer.
The cartridge used by this weapon, SP-4, instead of propelling bullet directly by gasses, uses piston system. Piston, accelerated by gunpowder explosion, pushes bullet out of the case, and seals gasses inside the case afterwards. This allows weapon to shoot quietly and without muzzle flash. See illustration.
It is fed by 6 round detachable box magazine and uses recoil operated action. Among interesting things in the construction of this pistol is the guiding rod located on top, and moving chamber. After shot, chamber moves backwards and only then the barrel starts moving. This is done in order to prevent case to get ripped apart during extraction, since pressure inside it is quite high.
