Much earlier than I thought
CHECKS B-29 TURRET IN ENGLAND U. S. AIR FORCE GUNNER John K. Bryan, New Orleans, L>* itrip* tin ammunition belt from the turret of a B-29, soon after.tho arrival.of the U. S. superfort in England. Sixty U. S. "Forts" and five C-54f-will, based "temporarily" at three British R.A.F. base*. (International).