S4M Russian Pistol

The S4M was a highly secret Soviet special-purpose pistol developed during the Cold War for covert operations. It was designed not as a standard military sidearm but for intelligence work, particularly silent assassinations and close-range missions.

It was developed in the early 1960s and adopted around 1965, linked to organisations such as TsNIITochMash and produced by the KBP Instrument Design Bureau. Production numbers were small and tightly controlled, as the weapon was issued mainly to KGB operatives and special forces.

The S4M has a distinctive two-shot, break-open design with two barrels arranged vertically. It is manually cocked and uses a simple loading system with no automatic ejection of spent cases.

Its most important feature is its unique 7.62×63mm PZ-type ammunition, derived from rounds used in the AK-47. The cartridges contain an internal piston that pushes the bullet forward while sealing gases inside, making the weapon effectively silent without a suppressor.

The pistol was intended for short-range covert use, where silence and concealment were critical. However, its two-shot capacity and limited range restricted its practicality. It was eventually replaced by more advanced silent weapons such as the MSP pistol and the PSS pistol.