The gunner entered the ball turret via a door at its rear, which also served as an emergency exit in case of trouble. The gunner could enter the turret from inside the plane by having the turret rotated until the door opening faced the interior of the plane. However, since this required that the ball turret be positioned so that the guns were pointed downward, this meant that the turret could not be entered from inside the plane while it was on the ground.
It was possible for the gunner to enter the turret from outside the plane while it was on the ground by having it rotated so that its door faced outside the plane. However, once he did this, he would have to stay inside the turret during the takeoff. Since the turret was only 15 inches off the ground, it would take a bold soul to ride inside the belly turret during take off or landing, and most ball turret gunners chose to enter the turret while the plane was in the air.
Normally, the guns were stowed facing rearward with the barrels horizontal for takeoffs and landings.
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