Maybe I am overthinking this, but how much copper in the barrel acceptable? I have one gun that I purchased used. Last summer it took a lot of work to clean the copper, but grouped .75" by hunting season. I have maybe 40 rounds since cleaning the copper. Today I added another 15 rounds just goofing off with milk jugs. I noticed it doesn't shoot as good as just before elk season. When I cleaned the gun this afternoon I noticed copper between every rifling at the muzzle. Here are my questions: 1 Is this barrel going to always copper up? 2 Did I not clean the copper out enough previously? 3 Is this normal? 4 What would cause this gun to do this so quickly compared to my other rifles? Suggestions?