None of you going to test this offline at all?
Anecdotally you can dismantle test a B25 in the drone circuit while counting rounds or over time. Or use a stop watch and sit behind it. See how long it takes to cut off a wing shooting at the same spot with all test planes. Or some part of the B25 but, the same part for each fighter. That will eliminate differences in the .50cal programing for each fighter and leave you with differences in relative harmonization aspects since your testing speed will be sitting at about 250 behind the B25.
P51D---275, 300, 325
F6f-----275, 300, 325
F4f-----275, 300, 325
F4u-1A, D, 4----275,300,325
P47D 6 gun package----275,300,325
It may make for a better test of the .50cal programing to set all convergence to 300 since the coad was an inferred possibility as the source of the presented problem.