Use SHOOTER'S CHOICE. It will remove copper fouling. Clean as normal until most of the nasty black stuff comes out. Run a patch soaked with SC through the barrel and let set over night. In the AM run another patch soaked with SC through the bore. If you get a green-blue color you have copper fouling continue this procedure until all blue green doesn't appear. In the process run a copper brush through the bore to remove stubborn fouling. the SC will eat up a bore brush so clean it after use. Continue this procedure until blue green doesn't appear, may take sometime but a good cleaning works wonders. Good luck and good shooting!