That's really bizarre. JB/Kroil is the only thing that I have found that DOES remove copper effectively! Effectively being the key word, because a lot of ammonia based solvents remove copper....slowly from my experience.
I am a little lost, I guess. The JB' is the scrubber and the Kroil is the lube?
Don't get me wrong here as that is the same thing I used for a while.
They both have their uses. But to get all the copper out, is a lot of scrubbing. Then it is questionable if it is clean as new, or close. I thought back then the Kroil and JB was doing the trick. Then I ran some Barnes through the bore and got blue patches.
I am no scientist, but I suspect the Kroil and JB just knocks everything down smooth?
Some interesting angles and thoughts here on this thread.
One thing I have fought with is carbon. I can't say I have a carbon ring at the throat on anything, but then I wasn't looking for such a thing either.
Worst carbon cases I have ever fought with was on some of the milsurps I play with. It absolutely crazy how many layers of gilding metal,carbon and powder can build up in years and years of shooting.
A long soak in Kroil is a my beginning attack method. Plug the muzzle, filler' up, stick muzzle in a can and walk away and forget it.
Kroil and Hoppes, smell of a good day! ;-)
Jeff