Hoppes #9 is a fine cleaning solvent and it will not harm the finish. But my experience says there are much better solvents for removing lead or copper.
For lead, I soak the bore with Ed's Red (about the same as Kroil) overnight. It seeps under the lead making removal much easier. Then I use either a Lewis Lead remover, or some strands from a pure copper Chore Boy wrapped around a worn out brass brush. The lead comes out in flakes. Not much effort at all.