Thrash,
just for arguments sake, since I'm
a card carrying serial killer in the P-47 with full ammo .50s, take an A-20 up with 25% fuel. Go find a spitfire who is playing with himself. Squeeze the trigger at 600 meters - see what happens.
I bet, either he gets masafuk'd within 1/2 a second, or you probally took a wing. Next try a 38, same setup. Then go to a P-47, set yr inside convergence to 475 and yr outside convergence to 425. Report back. If yr still having trouble, I'll ride jumpseat with ya and do some instructor student time.