Mr. Max Popenker sent us this photo he took of a range of Soviet-era Spetsnaz and KGB pistols. Max writes …
From quiet to silent: Soviet Spetsnaz pistols, L to R: 9×18 PB integrally suppressed pistol, 7.62×63 S4M silent pistol firing PZAM gas-seal ammo, and 7.62×35 MSP silent pistol, firing SP-3 gas-seal ammo.
Both organizations demanded pistols that were both silent and shot ammunition that would have been very confusing to military or law enforcement investigating shootings.
The SP3/PZAM cartridge was based on the 7.62x39mm round and later even fired the same bullet as the 7.62×39 M43 ammunition. Anyone finding the bullet (in a body for example) would assume it had been fired at long range by a AK, not a concealed pistol (long range because the velocity of this round when it hit the target would have been very low compared to a full power 7.62x39mm round). As far as I know, no shootings with this cartridge has ever been reported in the West, which means either it was a very successful cartridge or it was not used often or at all.