Muzzle - of any hunting gun, not just muzzleloaders - is sometimes taped to keep out any unwanted material (water, small branches, etc.) while hunting, especialy so in rough terrain and bad weather. This was recommended by P.O. Ackley in one of his books and I followed it for a while but now I mostly just check the bore for any obstructions from time to time.
Regards,
Jani