ORIGINAL: octafoil

Mossbergman....I've cleaned some nasty weapons for other people before, especially muzzle loaders and what I've found work best for some bad build up is....runbore cleaner with a bore brush heavy in the barrel a few times. Let it sit for a couple of hour just like that. Thenrun the brush with cleaner a couple more times. Take a couple of patches thru it. Now this I think does the trick...I tear up a old Tee shirt and make "tight" patches a force them thru the barrel ( by tight I mean snug) I do this with clean tees until they come clean. Then oil'er up as prescribed. On some of the tougher Muzzle loaders, I've left the bore cleaner in over night.