I did a few hunts with a T/C New Englander in 12ga as well as an antique 11ga. percussion fowler. In the 12ga. I used 80gr. Goex FFg, a plastic shot cup and about 1oz. of Kent Tungsten Matrix #3 size shot that was stolen from factory ammo. In the fowler I used 80gr. powder, a fiber wad and the same charge of Tungsten shot. I shot a few geese and ducks and results were very good.
I've also hunted geese a few times with my 20ga. flintlock using 90gr. Goex FFFg, a fiber cushion wad and 1 1/8 oz. of Bismuth #4 shot. Having no choke in the gun I kept shots inside 25 yards and all the geese I shot were DRT.