For what it's worth, hunting with a fouled barrel in a centerfire rifle is customary and reccomended. However, the residue left in muzzleloaders, regardless of what propellant that you use, can cause corrosion very quickly. Fouling attracts moisture like a sponge, builds up quickly with muzzleloaders and can inhibit optimum accuracy. Consistancy is the important thing. Shoot the same bullet, charge and primer, clean the barrel after each sight-in shot at the range and hunt with a clean barrel, and you will have the same point of impact in the field, and arguably as important, maintain your bore's condition for the long haul.