GAU-8 Avenger

An aircraft built around a gun

The GAU-8 was developed alongside the A-X competition that produced the A-10A-10 Thunderbolt II AircraftThe Warthog: a straight-wing, armoured close air support jet built around the 30 mm GAU-8 cannon., from a specification of 1970. Both A-X prototypes were designed for it, although they first flew with an M61M61 Vulcan OrdnanceThe six-barrel 20 mm Gatling gun that has armed US fighters of every service since 1959. as a stand-in. [1] The complete gun system, properly the A/A 49E-6, makes up about 17% of the A-10’s empty weight. The gun matters so much to the aircraft’s balance that a jack must go under the tail whenever it is taken out, to stop the A-10 tipping backwards. [1]

The gun alone weighs 281 kg. With its drum, feed and a full ammunition load, the system weighs about 1,828 kg and extends roughly 5.8 m from muzzle to the rear of the ammunition system. The drum holds up to 1,174 rounds. Those are installation figures: the barrel assembly is only part of what the aircraft carries. [1]

How seven barrels work

The Avenger is an externally powered rotary cannon. Each barrel has its own breech-bolt assembly and fires once in a complete rotation. Seven barrels share the firing loads; General Dynamics also attributes reduced component impact loads to the mechanism’s continuous rotation. The arrangement is intended to sustain rapid fire while extending barrel and parts life. [2] [3]

The A-10 installation uses hydraulic drive and a linkless ammunition supply. [1] The manufacturer’s broader gun specification lists hydraulic, electric or pneumatic drive and linked or linkless feed. Those options describe the weapon family, not three drive systems fitted to an A-10. [2]

The cartridge matters

The ammunition family is 30 × 173 mm, but its projectiles do different jobs. General Dynamics distinguishes three principal rounds: [4]

Round	Role	What it does
PGU-13/B HEI	High-explosive incendiary	Uses fragmentation and incendiary effects against targets including personnel, trucks and ammunition stores.
PGU-14/B API	Armour-piercing incendiary	Uses a dense penetrator to penetrate armour and produce effects behind it.
PGU-15/B TP	Target practice	Provides ballistically matched ammunition for training, weapon tests and aircraft-system checks.

The manufacturer describes the practice round as ballistically matched to both combat types. That makes it relevant to training the weapon system, rather than simply providing a cheaper projectile of the same diameter. The listed roles do not establish a universal combat ammunition mix or guarantee penetration of a particular target. [4]

Rate of fire and dispersion

The A-10 rate quoted in the existing reference is about 3,900 rounds per minute. [1] General Dynamics quotes a maximum of 4,200 for the gun. [2] The two figures should not be treated as interchangeable installation settings.

The manufacturer’s dispersion specification is an 80-percent circle, five milliradians in diameter. That is an angular spread, not a promise that every projectile strikes the aiming point. [3]

Illustrative calculation: at a range of 1,000 m, a diameter of 0.005 radians gives approximately 1,000 m × 0.005 = 5 m. This is a geometric conversion of the published angle, not a predicted combat grouping: it does not model aiming error or aircraft motion. [3]

Integrating the weapon

The manufacturer lists average recoil force as 44.5 kN. [3] This is another installation consideration alongside the ammunition mass and feed system, rather than just a characteristic of the visible barrels.

The GAU-8 also equips the Goalkeeper ship-defence system, where General Dynamics identifies a missile-piercing discarding-sabot round. The same gun designation therefore does not imply identical ammunition or a complete A-10 installation transplanted to a ship. [3] Some Avenger technology also went into the smaller 25 mm GAU-12GAU-12 Equalizer OrdnanceThe Marine Corps Harrier's five-barrel 25 mm gun, carried in a belly pod; the F-35's GAU-22 is its four-barrel cousin. used by the AV-8B Harrier IIAV-8B Harrier II AircraftA vectored-thrust jump jet: vertical or short take-off, flown by the US Marines for close air support.. [1]

For the aircraft’s wider role, see the A-10A-10 Thunderbolt II AircraftThe Warthog: a straight-wing, armoured close air support jet built around the 30 mm GAU-8 cannon. article and the definition of close air supportCAS GlossaryJoint terms: Close air support. Air action by fixed- and rotary-wing aircraft against hostile targets that are in close proximity to friendly forces and that require detailed integration of each air mission with the fire and movement…. The Manual’s weapons-delivery module covers the associated delivery concepts.