Shooting 10,000 rounds through a .45 automatic (SIG P220) in a single day was, to say the least, an educational experience. Although the gun was cleaned after each thousand rounds, we ended up with a streak of copper virtually plated to the steel of each groove in the barrel. Conventional brushing was only slightly effective, even with a variety of solvents. I finally got the gun clean using a product recommended by an old-time gunsmith. It looks like a pot scrubbing pad from a clean kitchen. The loops and curls of the pad are silver in color. A couple of strips clipped off and wound into a bristle brush are enough. Using one of the currently popular pull-through devices might work, but might also take a little longer. Properly used, this product will have your barrel spotlessly clean more quickly than anything else I know of. (800) 342-1548; big45metalcleaner.com
