During World War II, polygonal rifling emerged again in the German MG 42 general-purpose machine guns, as an outgrowth of a cold-hammer forging process developed by German engineers prior to the outbreak of the war. The process addressed the need to produce large quantities of more durable gun barrels in less time than those produced with traditional methods, as the MG 42's infamously fast rate of fire tended to overheat the barrel quickly and thus warranted frequent barrel changes. The MG 42 successor, the Rheinmetall MG 3 machine gun, can also have polygonal rifling.