Well try the Pyrodex RS powder. Load 80 grains of it. And if possible go to the thicker patch. With the .010 patch you might be getting too much blow by. I would go with at least a .015 patch. A patched roundball is not supposed to be a real easy load you know. You short seat it, then you long seat it and finally drive that down the barrel onto the powder. Also start your shooting at 25 yards. That rifle should shoot real good. You might even have to push that rifle more then 80 grains. Time will tell. If you have some wad, try putting one between the powder and patch. With the pitted barrel it might help a lot.