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Cleaning the inside of an AR bolt carrier

Discussion in 'Gunsmithing and Repairs' started by 4v50 Gary, Mar 13, 2013.

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  1. 4v50 Gary

    4v50 Gary Moderator Staff Member

    Dec 19, 2002
    The trouble with scraping tools is that the bolt carrier's hole where the bolt is inserted into is not necessarily machined smooth. A scraping tool will only clean the surface it contacts and not the grooves it cannot clean.

    I dumped the bolt carrier into a ultra-sonic bath for 20 minutes. I soaked the same bolt carrier overnite with a Hoppe's saturated cloth. I even scraped at the bolt carrier with a bamboo BBQ stick.

    I destroyed an old 45 caliber handgun brush scrubbing at it; but success was limited as the bristles faced the wrong way.

    I finally found a dremel brass wire brush whose bristles faced forward. Perfect, except that the dremel wouldn't reach down that far. A scribe with a removable tip was found and the tip removed. The brass wire brush was secured in it and the scribe body placed in a drill press (and later a lathe). Turn on the press and hold the bolt carrier up to it and it cleaned up rather nicely.

    Why bother? It was an exercise for me in a class. Part of it was accomplishing the actual task itself. The other part was to figure out how.
  2. a5werkes

    a5werkes Member

    Apr 28, 2009
    I tried all the above mentioned cleaning methods.

    Finally, fabricated some brass rods that will accept threaded tips for brushes, dremel QD brushes, brass brushes wrapped in fine steel / copper wool etc.
    Wrapping the brushes in steel wool, etc, solves the direction of bristle orientation; once wrapped you can run the brush clockwise / counter-clockwise as you like.

    Use a hand drill at low speed, chuck the long brass rod and cleaning tip of choice and it cleans the AR chambers nicely without marring the internal surfaces.
    Various sized rods, both diameter and length, also provide cleaning options for revolver barrels and fixed barrel semi-auto's whereby you can introduce the cleaning tips from the muzzle end and rotate the
    brush heads in the direction of the riflings without any problems.

    I initially tried using standard brass gun cleaning rods cut to size, however the diameter of the rod was too small, i.e. flexed too much.

    Whistle while you work.

    Screenshot2013-03-13at124343PM_zps388a28d0.gif CIMG0308a_zpsa031f6f8.gif
    Last edited: Mar 13, 2013
  3. dfariswheel

    dfariswheel Member

    Dec 26, 2002
    There's two ways to clean AR bolts and bolt carriers of carbon fouling: Mechanical and chemical.

    Mechanical methods use scraping tools like the Magna-Matic, C.A.T. 4 tool, or the other tools that clean only the bolt or only the bolt carrier.

    The chemical method uses a dedicated carbon removal chemical like the excellent Slip 2000 Carbon Killer.
    The easiest method of using this is to really shake the jar, then drop the parts in the jar and let soak 15 minutes.
    Remove and brush. If the parts are still carboned up, soak another 15.

    This works very well because it gets into places the scraping tools may not be able to reach, especially in substandard parts that have a lot of machine marks, and the liquid gets into the gas key on the bolt carrier.

    Either method will do what's really needed, and that's to remove the carbon fouling from the critical areas that might cause malfunctions. Even if not every trace is removed, either method will be enough.
  4. rskent

    rskent Member

    May 28, 2006
    The land of blue sky and sunshine
    Hey Guys. I don't mean to be a jerk, but if you are getting a bunch of hard carbon buildup that needs special tools to get rid of you might want to take a hard look at your lubrication. Its clearly burning off.
  5. dfariswheel

    dfariswheel Member

    Dec 26, 2002
    Of course the lube burns off.
    There's no lubrication made that can withstand super heated incandescent gas at 2500 degrees and around 20,000psi pressure.

    The AR bolt and carrier WILL get carbon fouling which is why all GI manuals show methods of cleaning it off.
    The commercial tools and chemicals just make a faster/easier job of it.
  6. joeschmoe

    joeschmoe Member

    Dec 27, 2012
    No scraping tools here. Brass and nylon only.
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