Decoppering a rifle barrel

by Catoosa, Monday, April 23, 2012, 21:34 (4597 days ago) @ Charles

I have a 6.5 Arisaka that has a rough bore. When it's clean it shoots nicely, but a few years back it got so badly fouled that it wouldn't stay on a gallon jug at 100 yards. After wearing out a couple of brushes and my arm with little improvement, I tried this trick and it worked:

Dismount the barreled action from the stock, remove the bolt, and plug the chamber with a cork or wood plug. Stand the barreled action, receiver down, in a bucket and stick a small metal funnel in the muzzle. Heat about a half cup of Kroil on a hot plate, not quite boiling but pretty hot, and pour it into the bore. Let it stand for about 30 minutes, and then pour it out. Scrub the bore with a bronze brush, and you will get out lots of little strips and chunks of copper.

Apparently, when the hot Kroil hits it, the copper heats and expands faster than the barrel steel, and that makes it turn loose so the Kroil can get under it and lift it off. Then the brush pulls it out.

Kroil is combustible, so it probably wouldn't be a good idea to do this indoors or use any kind of open flame to heat it up.