Greener mentions roughing the muzzles in an attempt to slow the wads, preventing them from blowing through the shot cloud. He states that black powder fouling would render this ineffective after few shots, but I can not see this as being fact. The 'tighter' the constriction there due to fouling buildup, the more retardation of the wads would happen and the better should be the patterning. Besides,w hen you load the next shot, you will be somewhat cleaning the 'roughed' surface. This then means he was referring to BP loaded shot ctgs. which are, of course, loaded at the breech. With a smooth muzzleloader, a roughed muzzle should help prevent donuts and the roughed area is virtually cleaned each shot. I seem to recall Greener mentioned using a Tap for roughing the muzzles, but it's been a long time since I read that BIG book. Might be time again to refresh my memory?