A drum magazine stores ammunition efficiently and still allows extremely rapid feeding to the weapon It is generally flexible and may allow empty casings to be stored back in the magazine.
Only its muzzle of its seven (7) 30mm barrels poke through the nose of the A-10. To aim at the target the whole aircraft must point at the target.
At left is the body of an A10 showing the arrangement of the Avenger weapon system. The hollow zone besides the gun is for the forward landing gear.
The linkless drum magazine employs a spiral arrangement of the rounds. The body of the magazine features longitudinal "channels" whereas the inner rotor features a spiral grove. As it rotates, the channels force the rounds to go straight towards the face of the drum.
The differential ammunition buffer mounted on the face of the magazine serves two purposes. The first is to get the rounds from each linear channel of the magazine as they slide forward, and the second is to adapt the speed of the ammunition feeder to the firing rate of the Gatling, which varies due to progressive acceleration when firing commences.
The feeder is mounted on the buffer, it uses sprockets to engage the ammunition rounds and thrust them in the feeder chute. The feeder chute in the A10 the gun is fixed and is not flexible, for greater reliability. The feeding system is bi-directional, which allows to store-back fired ammunition (empty cases) and to unload or reload the gun from a port on the side of the plane.
A gear box between the gun and magazine to provide motion to both.
The photo at left illustrates reloading a a GAU-8 Avenger Gatling gun. 1500 rounds of extremely heavy ammo cannot be expedited manually so a loader is used. It is a device that is much like another magazine except that it is intended to feed the on-board magazine of the gun. It also extracts used or unfired ammo.