I would use 80 - 100 grains of loose powder. What type of bullet are you shooting, conical(fullbore), sabots, powerbelt? hornady XTP or TC shockwaves, and 100 grains of loose powder is a good all around load. If the supplied sabots are loose in your bore, and accuracy is poor, try MMP or some other tighter fitting sabot. A tight sabot is crucial to accuracy. The black powder forum has alot of good info. too.