PaulN/KS said:
Shot size no bigger than #2 and no smaller than #9...
For what it's worth, here are my loads:
28ga:
Small game: 60gr FFFg, 2 cardboard OP cards, 1 oz #6 shot, 1 OS card
Turkey: 70gr FFFg, 1 cardboard OP card, 6" jute cord frayed into a ball of fiber for use as TOW, 1 more cardboard OP card, 1 7/8 oz #6 shot, 1 OS card
Deer/hogs: 70 gr FFFg, 2 leather OP wad/cards, patched .527 RB or .515 PRB, with different patch thicknesses of course.
Now before you go trying these loads, my .54 smoothrifle is a Lyman GPR flinter with a GM smoothbore barrel that is 32" long by 15/16", so it is a heavy barrel with lots of steel in it, and the above loads are safe in mine, but may not be if yours is a light-weight fowler. I really don't know since you didn't specify what exact gun you're using, so the above loads may or may not be of any use to you. I use the heavy shot load when required to use loose shot (by land owner), and it gives a good pattern out to about 30 yards with my gun, but when allowed to, I switch to the PRB (allowed by State law) and get good turkey killing groups out to about 60 yards.
And I use #6 shot just because that is what I can make myself, and it works for my needs. I have experimented with #4 buckshot (.240"), but my patterns weren't good enough for anything past 20-25 yards, so I standardized on the loads above.