I just broke in a McGowen barrel in 6BR last Sunday. There was absolutely no copper fouling at all, and I used the same foam and cleaning method that always shows copper in my Shilen barreled 204 Ruger. Just screwing around trying to find the right COAL I was getting multiple sub half inch 5 shot groups at 100 yards using a powder that was not ideal for the heavy bullets I was using. I'm really looking forward to seeing how it likes Varget. When I get this dialed in I think this barrel will be capable of getting in the .200s if I do my part.