The MSP Groza silent pistol (Russian: Малогабаритный Специальный Пистолет «Гроза», romanized: Malogabaritnyy Spetsial'nyy Pistolet "Groza", lit. 'Compact Special Pistol "Thunder"') is an over and under, double-barrel, derringer-type firearm designed in the Soviet Union in 1972.[1] The firearm is chambered for the silent 7.62×38 SP-3 cartridge which can be loaded via a two-round clip. The weapon was designed at the request of the Soviet special services. It is no longer in production, having been superseded by more modern designs.
The Groza uses a specialised cartridge. When fired, an internal piston within the cartridge launches the bullet forward and retains all the gases within the case, thus making a near silent weapon with almost no flash.[2]
To load the weapon the user would depress a button, allowing the barrels to tilt forward and exposing the breech for manual loading either by individual cartridge or with the use of a disposable 2-round clip.