Boilerman, that is the way I've been doing it. A few patrols back, I was in the USS Perch, a porpoise class. I was badly damaged by planes and sinking in the aft if I submerged. So I manned the AA gun, told him to fire at will, I maneuvered, and fought it out with the next few planes. None were shot down (It's TMO) but we managed to fight them off. My AA gunner has 100% skill now and I was sure to give him a medal when we got back to port
I didn't even have to load. I rarely do, only if I die which has only happened once in this campaign with the super duper destroyer, but that's anouther story...