A general-purpose machine gun (GPMG) is an air-cooled, belt-fed weapon with a quick change barrel that can be used in a variety of roles, from bipod- or tripod-mounted infantry support, to deployment as a helicopter door gun, or a vehicle-mounted support weapon. Modern GPMGs fire full-power rifle cartridges such as the 7.62×51mm NATO, 7.62×54mmR, 7.92x57mm Mauser, etc.