Sounds like copper, and plastic deposits in the bore. You will not see this looking in the bore. Give the bore a good cleaning, and then wet a patch with Hoppes #9, yes, the old stand-by, Hoppes #9. Let it stay in the bore over night. Next day, run a dry patch down the bore. Is it blue/green? If it is, this is copper build-up. You may have to repeat this process for a few nights to get it all. The instructions that came with my Triumph caution against using bore solvents with ammonia. I have found that many lead/copper solvents/removers contain ammonia. Hoppes #9 does not contain ammonia. It might take a little longer, but it is safe for the bore. Good luck, and let us know how you make out.