To answer (what I now believe was) your original question:
Yes, powder burn marks can be easily cleaned from a revolver cylinder and frame using a little solvent and a copper brush or scrubber.
Looking at the pics, I would be surprised that someone who would so carefully clean the cylinder/frame would be careless about the barrel. Either way, if you are finding copper in the barrel, then I would suggest "Like New" is a more accurate description.
Also, unless you ran some copper solvent through the barrel before giving it to your friend (which you may have) you won't know when the copper was deposited; it may have been your friend, it may have been the factory, or it may have been the individual who sold it to you as "unfired".