You might also try either JB or IOSSO bore paste/polish. This would also smooth out any rough area's in the rifling. Another good one that comes to mind now,is, a bore paste from Remington called 40X. It's like a thinner version of JB, comes in a plastic bottle with a ball bearing in it, like a spray paint can. Shake it till the ball bearing rattle's. It comes out like gravy, and you can feel a little grit in it. I used it years ago on my muzzleloaders, when it was called Gold Medialion. I believe it was made to get plastic fowling out of shotguns.
Part of the reason your gun(s) lead up, or copper up, is if you ever got a chance to look down a barrel with a bore scope, it's really pretty neat. There are microscopic etchings in the rifling. The more you shoot it, and the more you clean it, your polishing out those little scratch's. The smoother it is, the less it leads,or coppers, up. gypsyman