I finally flew a bomber and, although it seems it's getting fixed, I'm pretty sure it's the same "gun pointing to the same place as the last gunner position you were in" thing I described above.
With the new mouse-head-move thing though, it's just your head looking and the gun meeds to catch up to where your head is.
Almost.

When you hop from one gunner position to another, the guns will stay pointed towards the same
absolute direction (= relative to the
plane). However, since the new version your
view in the new station you just hopped in will be the same
relative to the last stations view. That can happen to be the same (for example when you hop from top to ball turret)... but when you hop from front to ball turret, yiur view will suddenly be nto the exact opposite direction as 12° clock relative to the ball turret position is actually 6°clock absolute! You are suddenly looking into the wrong direction, and to make it worse, the guns instantly swivel around to match your view....