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 military and civilians alike. 7.62×39mm ammunition is purportedly tested to function well in temperatures ranging from −50 to 50 °C (−58 to 122 °F) cementing its usefulness in cold polar or hot desert conditions.