For barrels, a patch cut from lead remover cloth and a brass (not plastic) jag tip. It's been a long time. It's true that a proper matching of cylinder, barrel, and bullet dimensions along with matching the hardness of the alloy to the load will prevent leading.

It sounds complicated but the reality is most of the time the throats are a bit tight. Simply opening them up to bullet diameter tends to solve a whole lot of problems. At least that's been my experience.