In my Black Diamond XR when shooting black powder, after ten shots it is sometimes necessary to pull the bolt and the nipple and wipe both of them down. I think it depends on the humidity actually as to how fast it collects fouling. This is also when I take the opportunity and give the breech plug a twist back and fourth to make sure it is not seizing up. The Black Diamond is a great rifle, but a more fouling rifle, I do not think was ever made.