Greetings, new poster here. I recently purchased an Rem. 700 sps tactical in 308 and looking from the muzzle end there is a whole lot of fouling on the left side of the bore in about the last 4 to 5 inches of the barrel. (Came this way from remington, rifle was nib) Never seen anything like it. I did over a hundred passes with Hoppes no.9, some nitro solvent, and 50 bmg copper cleaner using copper (with hoppes and nitro) and nylon brushes and patches but it's still there. The patches started out real dirty but have come fairly clean. Any suggestions on other cleaners or what it might be? I can definitely tell it's not tooling marks. I have shot the rifle and accuracy was acceptable for the extremely flexible hogue stock and lack of bedding. The fouling doesn't appear to be stacking on the bad spot either but I just can't stand seeing it.