I thought the convergence for buffs referred to the point at which all guns aimed when fired simultaneously. Even with the dual gun positions in the ball, upper, tail, and chin turrets, I figured the guns were close enough together to effectively fire at the same point. Could it be that the convergence is mainly for the elevation? Granted, on a shot to either the 9 or 3 oclock positions you spray a wide area, but a burst toward the 12 or 6 oclock positions has most of the guns arrayed in what is effectively a straight line.
Maybe I'll up one in a bit and do some testing. Anyways, I'm just glad to be able to set the convergence. Thanks again for the tip, Curly, I'd have never thought to manually edit the .cfg file.