In the late 1970s, while designing the GAU-8 Avenger for the A-10 Warthog, General Dynamics developed a smaller NATO friendly counterpart. The GAU-12 Equalizer would incorporate similar design features while using the slightly smaller 25mm ammunition. A small but notable step down from the 30mm ammo used in the GAU-8 Avenger. Using five barrels instead of the GAU-8’s seven, the smaller lighter cannon saw more diverse use.
Utilized on various aircraft since its introduction, the GAU-12 is most commonly seen being used aboard the AC-130U. Pared alongside a 40mm L/60 Bofors cannon, and a 105mm M102 howitzer, it would come to be known as the “Spooky”. Utilizing thermal targeting systems this platform would become an invaluable asset to ground troops needing CAS (Close Air Support).
Type: Five-barreled rotary cannon
Caliber: 25 mm (0.98 in)
Length: 83.2 in (2.11 m)
Weight (complete): 270 lb (122 kg)
Rate of fire: 3,600–4,200 rounds per minute
Muzzle velocity: (HEI) 3,400 ft/s (1,040 m/s); (API) 3,280 ft/s (1,000 m/s)
Projectile weight: (HEI) 6.5 oz (184 g); (API) 7.6 oz (215 g)
Muzzle energy: (HEI) 73,400 ft·lbf (99,500 joules); (API) 79,300 ft·lbf (107,500 joules)