If your Buckhorn... that replaced my Staghorn likes the same things, then 90 grains of Pyrodex FFg and a 240 grain T/C Mag Express XTP or 90 grains of FFg and a 348 grain or 295 grain Powerbelt.

Personally, save yourself some money. Get a see through powder measure and some loose power. You will save a lot of money in the long run and tune your rifle a lot better.