I agree with bronko22000 about Hoppes Elite. Very low odor, (keeps the wife happy, and the deer not so much), and given enough dwell time softens copper fouling as well, so a bronze bore brush can remove it with a bit of elbow grease.
Once the bore is clean, I swab it dry then use a very small amount of Birchwood Casey Barricade as a perservative, which, once dry, doesn't need to be removed before shooting. First shot is in the group.
Best I've found.