This is awesome! I had range session with my CBI barrel on Sunday and I fired 50 rounds through it, but mine is red inside. Maybe it has to do with bullet jackets, I was using Hornady A-Max and SST, Sierra SMK and PH, also Lapua Scenar. That was my 260 barrel, but I also shot my 6BR and it has no visible signs of copper, there is something about that 260, but it groups well.