Autocannon

An autocannon is an automatic, rapid-firing cannon that launches shells, typically larger than 20 millimeters. It is used against aircraft, vehicles, and other targets.

Automatic firearm: A firearm that continues firing while its trigger is held, using energy from each shot to cycle its action. Autocannons use automatic cycling to fire successive shells without manual reloading.
Cannon: A large-caliber gun that fires projectiles using expanding propellant gases. An autocannon is an automatic member of the broader cannon family.
M61 Vulcan: A six-barrel, electrically driven 20 mm rotary cannon developed for aircraft use. The Vulcan exemplifies the high firing rates achievable with a multibarrel autocannon.
Machine gun: A fully automatic firearm that typically fires bullets smaller than cannon shells. The distinction often rests on ammunition size and projectile type, though thresholds vary.
Anti-aircraft warfare: Military methods and weapons used to detect, deter, or destroy aircraft. Autocannons became a central option for short- and medium-range defense against aircraft.
Recoil operation: A firearm operating principle in which recoil moves parts of the action to eject a case and chamber another round. Many autocannon actions harness recoil to cycle after each shell is fired.
Cannon shell: A projectile fired from a cannon, often carrying an explosive charge or specialized payload. Autocannons fire shells rather than the smaller bullets typical of machine guns.
GAU-8 Avenger: A seven-barrel 30 mm rotary cannon designed for the A-10 attack aircraft. Its aircraft installation demonstrates an autocannon optimized for attacks on ground targets.
Howitzer: A cannon designed to fire shells on relatively high, curved trajectories, commonly for indirect fire. Howitzers prioritize long-range artillery trajectories rather than rapid direct-fire bursts.
Strafing: An attack in which an aircraft makes a low-altitude pass to fire on targets with guns. Aircraft autocannons made strafing a major form of close air support.

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Rotary cannonNarrower topic: Rotary cannon is a multi-barrel design within the broader class of automatic cannon.