Pyro P
 

I've been using Pyrodex "P" in all my BPs for years. Started using it due to periodic hesitation problems. It solved that plus burns cleaner. I use a formula I worked out for rifles that works out very well.
3.1416 X Radius sq X barrel length X 15,72 = load for patched ball and 50 cal sabot 45 cal 240 grain.
Tweak from there.