What do your patches look like?? What are you lubing them with?? Most don't pay attention to them after they have shot but since you are using a thin patch and a hot powder (777) I bet you are burning through the patches so they can't impart spin on the ball and accuracy goes to heck...

Change powder and go to a .015 or .018 patch...You won't notice much difference on how hard it is to ram the ball down because once you get past 5-6 inches the lead ball has conformed to the barrel...

777 is hit and miss as far as ignition in a percussion gun because the ignition temp is so high...

If at all possible get a pound of Goex FFF...It's real black powder and ignites at a lower temp, that's why it's so hard for some people to find...

I use 80grs FFF in my .54, that is also plenty in a .50 with a ball...