I was using 15 grains of 777 with lubed wonder wads. The guy in the shop just tried a .454 ball ontop of the chamber and it looked ok but they press in easy and it doesnt shave anything off really.
I wouldnt really call it a grouping lol they were a bit all over the place. I dont have sights adjustable for elevation.
Perhaps with tighter fitting balls I might get better consistency?