Just finished a Lyman GPR, my first black powder arm, and took it to the range. Very tight group at 25yds with 60gr Swiss 2f, but on 8th round, rifle would not fire. I found patent breech to be totally clogged with fouling. What did I do wrong?? Was using 495 ball with dried moose juice .015 patch and swabbed bore with juice between shots. Any help/thoughts would be appreciated.