Muzzle velocity
The GAU-8 itself weighs , but the complete weapon, with feed system and drum, weighs with a maximum ammunition load. It measures from the muzzle to the rearmost point of the ammunition system, and the ammunition drum alone is in diameter and long. Power for operating the gun is provided by twin hydraulic motors pressurized from two independent hydraulic systems. The magazine can hold 1,174 rounds, although 1,150 is the typical load-out. Muzzle velocity when firing armor-piercing incendiary rounds is 1,013 m/s, almost the same as the substantially lighter M61 Vulcan's 20 mm round, giving the gun a muzzle energy of just over 200 kilojoules.