7.62×45 SP-16

The SP-16 internally suppressed cartridge is an evolutionary development from SP-4 round. Designed by Russian TSNIITOCHMASH, SP-16 features same basic design with niternal pusher piston that propels the bullet out of the gun and then locks powder gases inside the case; however, it features larger case and redesigned projectile, made of steel, with chisel-shaped nose for improved penetration. So far it is used in only one gun, the PSS-2 noiseless pistol of Russian origin.