[idonno]

So lets just say that the loader on the B-25's is dealing with a 20lbs complete round.

I would say that your B-25 loader could probably have his gun reloaded in under 10 seconds rather easily. Maybe even half that time. He has a lighter round to work with, and as his shells would be brass cased rather than combustible, he might be able to skip the steps of having to pull one from a rack for the first reload and instead simply have it sitting on his lap or held in his hands. ('Lap-loading')

"The 75mm ... cannon shells were 26 inches long and weighed 20 pounds each and were stored in a rack just above the breech of the big gun and back of the pilot. The rack contained 20 fused shells."



"This 75 mm had a upward sliding breech block that retracted down at full recoil, ejecting the used shell casing and the Cannoneer would then, as fast as he could, slam the next sell into the open breech causing the breech block to slide up to be instantly fired by the pilot..."

Looking at the illustration, it seems the loader merely had to cause a round to drop down into the loading tray. It sounds and looks like it would be a very quick process.