Mosty people don't understand that not only can they turn the AC with rudder while in a gun position,they can also set there speed to auto climb at 250, when the air speed drops after the climb the nose will dip down and try to regain speed,this causes a slow up and down motion,coupled with your rudder turning. MUCH better then a plane flying level dodging back and forth through the enemy's gun fire.
Best thing is it can be done in any ac with rear guns, and in bomber formations it can become deadly.
Try it some time guys, you wont ever consider your fighter bomber/bomber a sitting duck.
(worse comes to worse it gives the impression your bomber is being manned by another gunner, and that will always give you a psychological advantage.