I need to work on my gunnery big time then. I wind up with only two guns quite often...having shot over, under, and around everyone.....
Learn to set your converg to 350 or less, I use 325 in 99% of the planes, the only real exception is the 109K.
Get well under 400, take a shot and learn to conserve ammo, if you spray 'n pray - you generally won't hit anything but your ammo counter.
80% of my shots are under 200, 20% were at 400, sometimes just tapping someone at 400 will get them to turn, closing the gap for an easy wing shot.