Hi hegyck,
We're not doing prone rifle shooting so you'll get scatter anyway from relative movement of the aircraft. Speaking of which I am old enough to have shot 0.303 rifles in competitions as a lad and we would put shots inside an 8 inch (?? I seem remember it was almost the size of a human head) bullseye at 200 yards time after time so I suppose your dispersion does come from the Browning machine gun action and vibration (0.303 Bren guns were harder to group).
I doubt if 1C have modelled the Browning dispersion anyway, they have enough trouble with a Merlin engine.
