Machine guns are automatic military weapons. They are mounted (on a vehicle, stand, bipod/tripod) and portable (not handheld) and usually fire at at least a few hundred rpm. They usually use ammo belts, and sometimes magazines. They are usually used for suppression and can fire for a long time without stopping (heating up, running out of ammo, etc.). A good example of a machine gun is the .50 Cal Browning Machine Gun (nicknamed Ma Duce).