Well if you r on realistic the gun will reload and it takes a while. but if u r on limited ammo u literally run out of ammo and it never comes back untill u die.

lol that's realistic, all right. Even b-17's often ran out of ammo long before making it out of enemy territory, at which point they were sitting ducks especially if they fell out of formation.

A couple months ago I linked a guncam video I found of a winchestered b-17 being leisurely done in by a bf-110 from 6 o'clock level. The 110 casually lit up all 4 of its engines in one strafe.

I've got one effective way of improving bomber fire, but I had to sacrifice the rudder. Make a custom controller layout, similar to aviator, but eliminate the rudder and move the trigger to the shoulder buttons. Then you can move the crosshairs and fire at the same time.