The 7.62×39mm round is a rifle cartridge of Soviet origin that was designed during World War II. It was first used in the RPD. Due to the worldwide proliferation of the SKS and AK-47 pattern rifles, the cartridge is used by both militaries and civilians alike. 7.62×39mm ammunition is purportedly tested to function well in temperatures ranging from cementing its usefulness in cold polar or hot desert conditions.