Probably gonna open up a can of worms, but what is the best solvent to remove lead?
Seriously? Mercury. Cork the barrel, leave it in overnight, and pour it out in a strainer the next day. You'll have pieces of lead in the strainer.
That said, you must have the proper HAZMAT tools to do this.
It's not for the average person any longer. Easily absorbed heavy metal, dude!
Speaking of which, the black stuff that will come to the top when you throw sawdust or wax or whatever into your lead, it's easily absorbed. Have good ventilation. This season I believe I'll start using a respirator, too. Dispose of that stuff safely.
Back to removing lead.
Even with poorly sized bullets, as long as you have a decent lube, you should be fine with a copper brush. I just pull a Bore Snake through from the chamber end, then from the muzzle end, and most of the lead comes out, if I have any.
For bad leading, try this:
Lewis Lead Remover at Brownell's
Never used it. Some swear by it. I see no reason it wouldn't