Alright, I've got seriously stubborn leading in my 9mm CZ, which I'm betting is in part from forgetting about it and shooting my messy lead reloads before some FMJ. Most of the crud came out pretty easily, with a good scrub and soak in a 'salad dressing' of 50/50 acetone and automatic transmission fluid, which does well in the garage. But this stuff crammed into the grooves has been utterly unaffected by brand new bronze brushes, the 50/50, Hoppes #9, a few strands of knockoff Chore Boy (which turned out to be plated, not pure copper like it actually says on the package ), 40X bore cleaner, and the WD40 and teflon-based 'penetrating oil and lubricant' I figured wasn't going to hurt, and all combinations. And I can't find Kroil in the local places for the life of me. So, is PB Blaster safe enough to use? Is there an actual lead solvent, or something else that works as well as Kroil? Most penetrating oils, I've found, are just ATF with cleaners in them, or an attempt to recreate WD40.