autocannon

An autocannon is a fully automatic firearm designed to fire explosive shells at high rates of fire and at calibers larger than those of conventional machine guns. Autocannons are typically chambered from about 20 mm to 40 mm and are mounted on ships, armored fighting vehicles, aircraft, and fixed installations. They provide firepower against light armored targets, aircraft at close range, and materiel targets that are not well protected against larger rounds.

Most autocannons are single-barrel weapons that are gas-operated or mechanically driven, while others use a multi-barrel rotating mechanism. Rotary autocannons, or Gatling-type guns, are driven by electric motors and achieve very high cyclic rates, often in the thousands of rounds per minute. Notable examples include the M61 Vulcan (20 mm) used on many fighters, the GAU-8 Avenger (30 mm) on the A-10, and the M242 Bushmaster (25 mm) on armored vehicles. The 40 mm Bofors has also served as a widely used autocannon in naval and land roles.

History and role: Autocannons began appearing in the early 20th century and became common on warships and aircraft in the World War II era. After the war, advances in fire control and cooling enabled more capable rotary and single-barrel designs. In modern forces, autocannons fill roles ranging from point defense and close air support to light anti-armor engagements, often in conjunction with missiles and other weapons.

Operational considerations: Autocannons require substantial power, robust feed systems, and adequate cooling to sustain fire. Ammunition types include armor-piercing, high-explosive, and high-explosive incendiary rounds, chosen for target type. Reliability, maintenance, and integration with fire-control systems determine effectiveness in combat.