OC-27M pistol PSA "Berdysh" is designed to equip military units and law enforcement agencies. The barrel has an integral feed ramp, and is quick, making it easy to change the caliber of weapon. Replacing the barrel allows pre-select caliber pistol. Three options are available: 7.62mm chambered for 7.62x25 mm TT, 9-mm chambered for 9x18 mm PM or PM-M and a 9x19 mm "Parabellum". To dampen the recoil momentum of the shock-absorbers. All these features have made the gun very popular among stalkers.