That may vary depending on whether you are shooting pure lead, or an alloy of some combination. Our hard cast pistol bullets shot fine in our .367 mganum with no evidence of melting, but they were as hard as wheelweights, or maybe harder! You might read the opening text from Steve Garbe's Black Powder Cartridge Reloading Manual, where he and Steve Venturini have spent much time explaining exactly how they load their ammo to get those 2 1/2" groups at 200 yds. using a Tang Peep sight, and a .40-65 or .45-70 rifle. They cover everything from the choice of casings, primers, powder wads and bullets, to how they position the bullets in the casings for consistency, and how they position the casings in the chamber for consistency. Add to that the latest writings of Matthews concerning primer pocket size, and using small pistol primers rather than large rifle primers to get even better accuracy( from the Single Shot Exchange), and you can squeeze out all the accuracy that fine barrel was made to give you shooting black powder. But, in the end, if you don't clean that barrel, everything else you do is wasted. You are right on that point. For other readers, we are talking about milking the most accuracy out of a rifle for the sake of long range shooting and small groups. Hunting accuracy rarely demands this kind of atteniton to loads, and no one but an moron would ever shoot at live game at the long ranges used today to shoot at targets with these guns. Respect for the game we hunt demands that we get much closer so that we have a decent chance of taking a second shot to humanely finish an animal that is wounded because something unforeseen occurs, like a gust of wind just as we release the trigger, a twig 20 yards in front of the animal that we didn't see, the animal turning so that we hit forward, or back of our aiming point, etc.
