Fugitive...are you making allowance for bullet rise (i.e. the arc described by the bullet from its origin {your guns where the bullets begin} to convergence {where the rounds from all of your guns fall to meet} ?
The ballistics in AH are set up so that the bullets "fall" into the convergence, in an arc, not "rise" up to convergence, as in a straight line. Thus, with convergence set at 325 and holding fire until 200, your rounds may be rising above your target if you have your sight set right on the target (this is based upon a dead six shot upon a non-maneuvering enemy aircraft...if you are deflection shooting, and waiting until 200 to fire, and your sight is right on your target, and the target is maneuvering a bit, you may be firing high and behind your target).
This post is based upon 6 wing mounted .50 caliber machine guns only, and my preference to shoot close to, or at, convergence against fighters. Against bombers, I make no changes in convergence, I merely change tactics a bit (yes, I kill more bombers than fighters, so my hit % is usually high, but against fighters I still average about 8-10% in fighter mode).
From your original post it seems you have no problem "saddling up", or "flying to the six" of your opponent, so I have to deduce that you are shooting too late (200 vs 325) for your convergence setting and most of your rounds may be going high. I would suggest that if this is the case, and your flying style gets you this close to an opponents' six...you may want to pull your convergence in a bit to flatten out the arc your bullets are taking to the target and be patient enough to watch for the shot I think you are seeing, but missing due to convergence issues.
This just my opinion...
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