Thread: KG 12 copper remover

KG 12 does work well but I found I needed to leave it in for about 24 hours. My 300 Rum had noticeable copper build up at the muzzle end and after scrubbing barrel with a nylon brush and KG 12 and leaving it overnight it had removed the copper.
I use it only when I can see the build up and in between use Hoppe's Solvent which I have used since I started hunting and has worked well for me. Patches do show green if you scrub and leave in for a day or two so it must be removing some copper.