Hoppe’s 9 Bench Rest copper remover gun bore cleanerHoppes No. 9 Bench Rest Copper Remover Overnight Copper Fouling Removal for Rifles, Shotguns & Handguns Copper fouling is the enemy of accuracy. As jacketed bullets travel down the bore, copper from the bullet jacket deposits in the rifling building up over hundreds of rounds and progressively degrading accuracy as the bores geometry changes. Standard bore solvents remove powder fouling effectively but struggle with copper, often requiring hours of