If all else fails with the bore, you can "crest" it. Basically, a small amount of "Crest" toothpaste on your bore brush and run it through a few times. THIS DEFINITELY A LAST DITCH TECHNIQUE FOR THE BARREL. Per my FBI sniper instructor, you can seriously harm the barrel if you do it more than once or twice. I have done it to a couple of guns followed by a good copper remover and it will remove a lot of whatever is in there.