Without doubt, the most difficult part of cleaning an AR-15 is the space at the back of the bolt carrier where the bolt fits in. This is an area that is subjected to the operating gasses of the rifle, and as a result it acquires a significant deposit of carbon. The hard carbon is very difficult to remove, and this is compounded by the difficulty in getting at this area where it collects.
Everyone that cleans an AR-15 has struggled with this task. Some have tried bore brushes, solvents, dental picks, and I've even seen some use screwdrivers to break off this hardened deposit. These time consuming methods are mildly successful, and sometimes damaging.
There is a better way. It is a purpose designed tool called a 'bolt carrier carbon scraper', and it is extremely effective. Resembling a short, stubby screwdriver, the carbon scraper breaks up the carbon deposits, and makes their removal a simple task.
Operation is simple; from the instructions that accompany it we have:
ENSURE THAT THE FIREARM IS UNLOADED
- Remove bolt carrier assembly
- Remove firing pin retaining pin, firing pin, cam pin, and bolt from bolt carrier
- Insert the carbon scraper into the bolt carrier as you would replace the bolt
- Pressing lightly, twist the carbon scraper clockwise to break up carbon deposits on the inner surface of the bolt carrier
- Clean carbon dust out of the bolt carrier with a cotton swab or cleaning patch
NOTE: The Bolt Carrier Carbon Scraper is not a metal cutting tool, it is only used to break up excess carbon buildup inside the bolt carrier. Care must be taken to ensure proper alignment with the bolt carrier. As with any reamer, turn only in the direction specified. Turning the Bolt Carrier Carbon Scraper counter-clockwise will dull this tool.
Versions of this tool can be found from different sources, and one of these is Brownells, of Montezuma, Iowa. The tool is manufactured by Mark Brown Custom (Los Alamos, New Mexico) and distributed under the Brownells, Inc name. Retailing for about $25, it is an indispensable part of AR maintenance. Brownells offers friendly staff to take your order 24 hours a day, and it was delivered within 2 days. Brownells can be reached at 515-623-5401 or at www.brownells.com. When you order, don't forget to request a free (almost 300 page) catalog - it is one of the best available for whatever your firearm needs.
Construction of the carbon scraper was actually better than I had expected. It is made from a steel bar stock fitted into a strong black "screw-driver" handle, and it is machined to fit closely into the bolt carrier. The "business" end of the scraper features four sharp cutting edges, and space for the broken up carbon to go. The very end fits into the back of the bolt carrier to provide perfect alignment.
The tool is well constructed, offers a nice tight fit, and works like a charm! Two or three twists is all it takes to remove years of carbon buildup. I was so impressed I went and cleaned 4 or 5 bolt carriers just to see it work! I'd definitely recommend it to anyone interested in maintaining their AR-15.