7.62x39mm

The 7.62x39mm is a form of ammunition that was created by Russia during World War II, being used for the AK-47.

Soviet Union
During the Virtuous Mission and Operation Snake Eater, various KGB and GRU soldiers, respectively, utilized the 7.62x39mm round for their AK-47s.

America
Aside from Naked Snake utilizing 7.62x39mm ammo during Operation Snake Eater, Soviet soldiers led by Gene occasionally used them with their AK-47s.