Got a copper problem? Hoppes Bench Rest copper cleaner can fix it. Shooting rounds down your barrel causes copper fouling where the jacket of the bullet meets the grooves. Hoppes cleaner removes the residue restoring your barrel back to bare steel. As copper builds up, it can change the velocity of your rounds causing issues and carbon to build up.Features : Removes copper fouling Removes plastic and carbon residue Use gloves while cleaning Always neutralize with oil after bore cleaner