Interesting tales [B-25 nose armament].
I remember reading that the pilot and co-pilot stated that the gun lay between them and that the plane seemed to "hesitate" when it fired. They could see the gun recoil right beside them. I guess the bombardier fed the shells into the breech.
I'd also guess that when the 3-inch wing mounted rockets appeared, this "upgrade" was obsolete.
Pic of guns being fired at night, HOOOAH
Obligatory nose art pic on a TB-25N
Last one for now, Gotta get to work :-)
Sorry don't have any "H" Model Pics, 75mm Howitzer model handy.
Regards
alfa6 ;>}