I originally put 129 and thought it wrong thats what happens when I do not consult my books yes it was used on the eastern front, other machines mounted the 2pdr Molins on the mossie, 2 x40mm on the Hunrricane, 2 x 37mm on the Stuka. I have seen footage of the 75mm being fired in the B 25 and it fairly makes the aircraft jump.
I have also seen the footage of the 50 cals on the 25 going off they had to reinforce the fuselage skin due to the blast from the muzzles that caused probelems. Even with it beefed up the side skin still compressed when the guns were fired, the horse power it delivered up front was awseome. Also in the clip was how they skip bombed the detonation usually happened on the 3rd skip primaraly used on Japaneseshipping in small coves that torpedoes would be ineffective having the wrong angle when dropped.