I would get rid of the abrasive cleaners. You're going to wear out that bore from scrubbing it too much. Try the electric method first. This is one way of doing it, and is reputed to work wonders on a dark bore: http://www.surplusrifle.com/reviews/copperout/index.asp
After you've done that, then you should think about using fine abrasives to smooth the metal back down. Firelapping is probably better than anything else, though. I know a lot of people like JB Bore Paste and all the other stuff, but that's like trying to clean a dirty window with Comet cleaner. Using abrasives in a bore are going to eventually wear out the bore. For simple cleaning, use chemicals and let them do the work. Don't rely on scrubbing or swabbing or any other mechanical action.
The electric bore cleaner will generally get your bore as clean as it's going to get, without scratching the inside. Just don't do it too long.