I can't seem to get the bore on any of my milsurp rifles ('03-A3, M39, 49/56, etc) to truly come clean after a shooting session. They all have excellent, mirror-bright bores, but no matter what I do, when I push a clean patch through the barrel it still comes out with a little bit of black on it. I've tried Hoppe's #9, copper solvents, foaming Gun Scrubber, CLP, tried soaking it overnight...nothing gets the bores clean enough to keep a patch from picking up a little black when I run it through.
I'm not one to wear out a bore by frenzied scrubbing with a bore brush, and anyway the barrels on my milsurp shooters are in excellent condition free of pitting and corrosion. I just don't understand the black in them that stubbornly refuses to clean up. Any suggestions would be muchly appreciated.