How are machine guns operated?

Machine guns are operated using a mechanism that cycles through the firing process automatically, typically through gas-operated or recoil-operated systems. In gas-operated machines, gas from the fired cartridge is redirected to cycle the action, eject the spent cartridge, and chamber a new round. Recoil-operated machines use the energy from the recoil of the fired round to perform the same functions. Both types can fire continuously as long as the trigger is held down and ammunition is available.