RE: EXACT steps to shooting for load develpoement.
It seems like, generally, most of my guns shoot the faster lighter bullets higher, in terms of point of impact at 100 yards; and heavier slower bullets print lower. Extreme spread might be around 12" at 100yards between a light sabot bullet with three Pyrodex pellets and a heavier lead conical with a moderate load of loose Pyrodex. All three of my in-line guns exhibit this same tendency.