The process for polishing a 12 gauge is pretty simple. You use a standard 3 piece aluminum shotgun cleaning rod and attach a 20 gauge brass bore brush to the end. Take a piece of green scotchbrite and completely cover the brass brush (1 revolution). Embed a good amount of JB Non-embedding Bore Cleaner in the scotchbrite pad, wet the pad with Kroil oil and using a battery operated drill on low speed, begin working the barrel from the end of the shell chamber to the choke end, back and forth. A vise, with a towel or piece of rubber wrapped around the barrel, makes a great clamping device to hold the barrel. Also use a small box at the choke end, to catch leakage and slinging oil from the scotchbrite if it exits the choke. Make sure you, remove your turkey choke and use an improved cylinder choke in the end of the barrel. You'll be amazed how much dirt, grease, grime and plastic fouling will come out of the barrel. Make sure you keep the pad saturated with the oil. As others have said, this is for steel barrels not chrome lined barrels. Chrome plated barrels have a thin layer of chrome, electroplated, inside the barrel and shouldn't be disturbed. Personally, I use this same process on my 50 cal inline muzzleloader. It cleans the lands and grooves really well, removes the powder fouling and makes loading the 45 cal sabots so much easier. There is a thread with PICS on this website.