If I have a barrel that needs one of the stronger copper cleaners, my first thought is not new solvent, but new barrel, or different rifle. All of my good barrels show little to no copper, once they have been broken in, and did not take very long to break in. My go to solvent is Butch's. I think that cleaning discussions should be divided into lapped and factory, and which is being discussed mentioned in the first post. In my experience, the requirements for each can be very different.
This is not to say that all of my rifles have fancy barrels, but the ones that I have kept, broke in so that the do not take extraordinary measures to clean.