1 1/4 oz of #2 bismuth over 4 drams of FFg in brass cases worked well for me in my 1883 Colt 10 ga. on Montana honkers last December.

I think the old colt could take a heavier load, but the recoil of 4 drams was enough for me and it seemed to kill geese as well as the 3 1/2 inch semi-auto guys I was hunting with.