I've heard a few mentions of bore butter here on this thread. I noticed barrel fouling in my Thompson Center Omega. I threw everything at it to try to scrub it out. Turns out the fouling is the bore butter that over time bakes in the barrel. Sort of like a seasoned frying pan. If you choose to use the bore butter for storage. Make sure you clean it out before shooting. Over time it will bake in the barrel. I've always kept my muzzleloaders clean and never leave them dirty. I threw my tube of bore butter in the garbage can. I still haven't got this cleaned out yet. I've tried J&B abrasive paste, scorching hot soapy water, Pasload impulse nail gun cleaner, abrasive aluminum polish, butches bore shine and a few others. Nothing has worked