Assuming an adequate powder charge the situation is a constant set of variables:
Pellet Count
Pellet Size
Size of shot charge
Distance
If any one of them varies something else usually has to change.
The smaller 7.5's fill up a pattern better than 5's-6's and absolutely will kill a turkey dead where he stands no problem at all...except they won't do it out at 30-40 yards...so distance limitation changes significantly.
Go to a larger pellet to get more energy at longer distances and the pattern thins out compromising some of that very distance...so the outer limits have to be pulled back some.
Finding that sweet balance point is the trick, where the best blend / best compromise of energy/penetration, pattern fill, and distance come into focus...might only be 20 yards, could be 40...all depends.
For a particular muzzleloading game bird that usually only involves 1 or 2 shots per season, an awful lot of BP, wads, shot, and cards go into pattern testing just for those 1 or 2 shots.
:wink: