I have had the same problem with my .300wm Rem sps. I then used the Gun Slick bore foam, cleaned with patches, and then used again and all the visible copper that I kept seeing at the end of the barrel came right out. I have been using the Rem core lokts 180grns. I would have to argue with the opinions of the accuracy of these rifles as I have had no problem knocking down 2 liter pop jugs at 450yrds with a small Nikon prostaff 3x-9x 40mm scope. If you guys don't like these rifles and are disspointed with them please send them to me i'll give them a good home
, heck i'll pay the shipping.