I should have attributed, sorry.

Randall Jarrell, published in 1945.

Bomber ball turret gunners and tail gunners had the shortest life expectancy of any combat occupation in the war, as these were the first targets of incoming fighters. I found one site that said tail gunners’ combat life expectancy was four missions.

Ball turrets couldn’t reload in flight. The ball was too small for parachutes, and the mechanisms jammed or froze often. Typically they put small, young, single guys in them.