The following is from *Fire int he Sky: The Air War in the South
Pacific* by Eric M. Bergerud (p. 626 HC) -- a quote from Rich
Walker, who flew a B-25 strafer for the 5th USAAF 3d Bomb Group.

"We would fly on one engine. A B-25 was pretty iffy on one,
particularly one of our homemade strafers. They destroyed the balance
of the plane by putting all that weight up front and pulling the
bottom turret out. That changed the center of gravity. They had a
slide rule you were to use to figure out your weight balance. We sat
there one day working the slide rule, and hell the slide nearly fell
out of the rule. So we threw it away."