Don't know all the specifics about all the bombers, but i do know this, of the 12 guns on a B-17, 8 were able to be takin of their mountings in flight. Considering the massive asssembly line construction of these bombers, I would believe that hand crafted mountings were not produced. These factors lead me to believe that some sort of "shaking" is going on. If the gun barrrel moved even the slightest degree from recoil, the difference in trajectory could be a plane width at least.
As for bombers being meat, I would agree with the Ju88 and the Lancaster are "easy" but no way is the 17 and 26 easy and sheesh, I don't think I've killed a Ki, they can outrunn my 109 lol.
The A-20s and Bostons are a dime a piece, but that goes back to the player being able to bank the plane while surgically removing the wings from my plane.
Mind you this post was not intended as a whine, just another bone tossed out there about adding some more "realism" to the game. I kill my share of bombers, more than kill me, so the current model is ok with me.