You need to come and clean my rifles so I can see the difference between your solvents, brushes, jags, patches and mine ha ha. A clean bore in my rifle means the bullet is an inch off and two shots later is absolutely perfect. Bugs the hell out of me. I have tested this extensively on my range but never been able to fully deal with it. I have used Butches, Hoppes No 9, white spirits etc amongst others. The solvent makes no difference as they are effectively the same kind of thing. If it eats in to copper, it removes the consistent conditioning already in the barrel.
I like having copper left in the bore, so I don't solvent and brush it that often as I like the barrel being conditioned. The idea of carbon cleaner and patched out is something I will try to see if it helps the rifle behave a little better post clean whilst leaving any copper residue in situ.