The Lewis Lead Remover or copper wool Chore Boy method are effective methods and the addition of some penetrating oil is a good improvement over doing it dry. I did happen on a better option and no longer go that route. At some point in my bullseye pursuits I took note of what the BP cartridge rifle shooters were doing to compensate for boolit designs that had marginal lube capacity for the long barrels they were shooting them out of. Leading and hard BP fouling were a problem for some. They dealt with this by seating the boolit on a card wad and a lube cookie so everything was in a snug column in the case. Powder gasses pushing the card wad and forcing lube out against the barrel wall as the boolit was going up the bore, thus anointing the bore with a film of lube that kept the fouling soft for the next shot. I tried that in various (smokeless) pistol and rifle calibers, reducing the load appropriately to compensate for reduced volume in the case and the result was pleasantly mild ammo, a generous lube star on the muzzle and leading disappeared. Thereafter, I kept a box of "cleaning rounds" on hand for after the matches. After 5 or 6 of those, all that was left in the bore was boolit lube. All I needed to get a clean barrel was a couple patches and a squirt of solvent. It took all the "sweat equity" out of cleaning and was much more pleasant.