I shoot a Lyman Trade rifle in that caliber. It will shoot .530 or .535 ball. I am testing both ball right now to see which one shoots best. Last year I was hunting with a .530 ball, .018 patch, and 90 grains of Goex 2f. Mine is a flintlock, so shooting black powder is very necessary. If you do not think that load has some power, last year at 52 yards I shot length way through a deer and the ball even had enough powder to break the back leg as the final insult before it dropped the deer where it stood.

I would guess that the Deerstalker would shoot 80-100 grains of Pyrodex RS, or Goex, or any of the sub powders well. I would start with a lubed .015-.018 patch and a .530 roundball. If you find loading too easy, then go to a thicker patch or a larger .535 ball.