Forgot to mention...
If/when you get "ball creep" in any gun, it creates post-compaction airspace between the powder and ball. This must be avoided at all cost! It can be downright dangerous!
Black Powder: Not because it is easy, but because it is hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win...