Cleaning the AR Bolt Carrier

**4V50 Gary** · March 12, 2013, 11:20 PM

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.

Striker1 · March 13, 2013, 12:49 AM

You plan on doing that every time you shoot it?

I always used a rod section to scrape off any big chunks of carbon, then followed with a chamber brush. These days I rarely bother and it doesn't seem to matter much with reliability.

ScottRiqui · March 13, 2013, 12:59 AM

I'm not saying the OP is this bad, but I have met AR owners who, if they treated their cars like they treat their rifles, would change the oil after every drive, along with pulling the cylinder heads to scrape the carbon off the pistons until they gleamed!

**4V50 Gary** · March 13, 2013, 04:29 AM

The purpose of the thread was to suggest an approach to cleaning the bolt carrier. As to why even bother, figuring it out was part of the exercise for a gunsmithing class.

Dfariswheel · March 13, 2013, 10:10 PM

From your similar post on another forum, my response:

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.

**4V50 Gary** · March 14, 2013, 07:07 PM

Thanks Dfariswheel for the suggestions.

BTW, prior to this experience the bolt carrier was placed into an ultrasonic bath for 21 minutes. It loosened a lot of dirt, but not the build up inside the bolt carrier.

March 12, 2013, 11:20 PM	#1
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,838	Cleaning the AR Bolt Carrier 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. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

March 13, 2013, 04:29 AM	#4
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,838	The purpose of the thread was to suggest an approach to cleaning the bolt carrier. As to why even bother, figuring it out was part of the exercise for a gunsmithing class. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

March 14, 2013, 07:07 PM	#6
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,838	Thanks Dfariswheel for the suggestions. BTW, prior to this experience the bolt carrier was placed into an ultrasonic bath for 21 minutes. It loosened a lot of dirt, but not the build up inside the bolt carrier. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

March 13, 2013, 12:49 AM	#2
Striker1 Senior Member Join Date: May 22, 2004 Location: TX Posts: 710	You plan on doing that every time you shoot it? I always used a rod section to scrape off any big chunks of carbon, then followed with a chamber brush. These days I rarely bother and it doesn't seem to matter much with reliability.

March 13, 2013, 12:59 AM	#3
ScottRiqui Senior Member Join Date: January 27, 2010 Location: Norfolk, VA Posts: 2,905	I'm not saying the OP is this bad, but I have met AR owners who, if they treated their cars like they treat their rifles, would change the oil after every drive, along with pulling the cylinder heads to scrape the carbon off the pistons until they gleamed!

March 13, 2013, 10:10 PM	#5
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,478	From your similar post on another forum, my response: 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.