Some ML's shoot more accurately with a fouled barrel while others shoot well either way. I have a Knight ML that shoots great clean or fouled, but I also have a CVA Kodiak Magnum that likes a slightly fouled barrel, and by that I mean I have to at least pop a couple of primers off thru it to lightly smoke the rifling, or it'll be off on a perfectly clean barrel shot. I have no problem fouling a barrel to hunt a couple weeks with, and if I hunted bad weather I'd just shoot that shot out before coming home and load with dry powder before heading back out. Blackhorn is much easier to do this way b/c it's not quite as corrosive as other BP subs, but I've done the same with Pyrodex for years as well.