The Sperry nose turret was tested and preferred, but its use was limited due to poor availability of suitable aircraft designs.

The Sperry ball turret was 3 and a half feet in diameter in order to reduce drag, and was typically operated by the smallest man of the crew.

This left him positioned with his eyes roughly level with the pair of light-barrel Browning AN/M2 .50 caliber machine guns which extended through the entire turret, located to either side of the gunner.

Normally, the gunner accessed the firing chamber by releasing a latch and raising the cover to a position perpendicular to the gun but this was not possible in the ball turret.

In the case of the B-24, the Liberator's tricycle landing gear design mandated that its A-13 model Sperry ball turret have a vertically retractable mount, so that the turret would not strike the ground as the plane pitches up for takeoff or during the landing flare.

It served a double purpose, defense against bow attacks as well as fire suppression and offensive strafing in antisubmarine warfare.

Since this turret is of the ball type, the gunner moves with his guns and sight in elevation and azimuth by means of control handles.