I use a "Slix-Scraper" to clean the carbon build up out of my .357 Mag (and .45 Colt) cylinders. Takes one or two revolutions of the tool and all that carbon built up is gone. Then follow up with solvent patch, etc. like you (should) normally do to clean the cylinders. They also work in .357 Mag/.45 Colt rifle chambers to clean the build up left behind after shooting shorter cartridges (shorter COL). I've tried brushes, etc. and the found the SliX-scraper to be a whole lot quicker and provides a much better result, every time. They're available via www from http://uniquetek.com/. You'll probably find a lot of other interesting gotta-have tools and gadgets when you roll through their on-line store as well. Use this tool once and you'll never scrub your cylinders with a brush again...and you won't miss it either.