Cleaning an M4, what a mess.

K

Kimio

New member
So not too long ago it was that time again and I had to qualify once again to retain deployable status. Typical fair of training as it was, the real interesting bit came when me and the other folks who shot with me had to actually clean the rifles we were issued.

These had to be some of the most filthy M4’s I have ever seen. Even more so than the M16 A2’s that I practiced with back in BMT. The rifles looked like they hadn’t been touched at all since the last 2-3 range sessions they’d been through.

The carbon build up along the O-ring and the gas key was so intense that it took a dental pick and probably at least a good 15-20 minutes me scraping away at it just to get it visible again. Corrosion was evident on the bolt itself as well as the firing pin which also required a great deal of care. Most of our cleaning kits were lacking even the most basic cleaning supplies and we were supplied with a small dallop of CLP to clean both the bolt and Barrel, which is clearly NOT what was needed to get these rifles cleaned up properly (good enough to keep going is the goal I suppose). The cleaning brushes and rods looked ancient and likely wouldn’t provide a good cleaning to the bore even with 4-5 passes due to the wear and tear I saw on them.

Me and about 4 others in my group commented on this and the instructors stated that the rifles are cleaned after every range session, however, due to the porous nature of the metals, carbon seeps into the metals and after they sit for a while, they come out and combined with firing close to 200+ rounds per student, their carbon fouling is quite bad by the end of the day. They get not nearly every day, so the issue just keeps getting worse and never has a chance to clear up.

I have never ever heard of this before and wasn’t sure if they were just speaking out of their asses or not, but figured more educated folks could enlighten me.

Is this a thing? I’ve shot hundreds of rounds through my own AR15 in a single session, and never had this ever happened with my own personal rifle, granted, it goes to the range, gets cleaned and is only shot sparingly these days due to budget constraints.
 
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" porous nature of the metals " , " carbon seeps into the metals " . As a metallurgist I would like a more technical explanation ! In the throat of a rifle the steel gets hot and the carbon from burning gases 'diffuses' into the steel .Is that what you mean ?
 
@Mete I honestly do not know, that is what my instructors told me is the cause of the severe carbon fouling on the bolt, gas key and within the chamber itself. Which is why I’m asking here. I’ve never heard of this being a thing before, I was always under the impression that once you cleaned the rifle that was mostly it. If done correctly, you shouldn’t have much of any carbon fouling, even if the rifle sat for a while. However, I don’t fire the same volume of rounds that these rifles would in the span of a year let alone a single week that these M4’s do.
 
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CLP only removes about 85% of the carbon. If all you clean with is CLP, you are going to get carbon buildup over time. This is why the armorer's manual calls for periodic cleaning with dry cleaning solvent followed by reapplying CLP.
 
...wasn’t sure if they were just speaking out of their a$$es or not...
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Ahhhhhh.... Forum rules inhibit my heartfelt reply. Wow.

That said, if these instructors would just shoot the bolts "wet" ... maybe even just squirt some standard 20-Wt into the ports every 3-4 dozen rounds or so... the bolt carrier group could be near wiped totally clean with just a paper towel at the end.

This ain't rocket science
 
"porous nature of the metals " , " carbon seeps into the metals " . As a metallurgist I would like a more technical explanation
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Anodized aluminum is somewhat porous, at least the surface is. Same with parkerized steel. Its the same principle that traps a thin film of oil and keeps it on the surface or somewhat "in" the surface. Blued steel, or any polished metal, does not hold oil (preservative) well at all. So I understand exactly why you question this, but the anodized aluminum in an AR receiver is porous enough to trap carbon. You can white glove clean an AR, add a light film of oil, and go back to it a few days later and you can dirty up some white gloves. I know I've done it inspecting weapons in the armory.
 
Carpenter #158 & 9310 steel for the bolt/carrier group, w/ various nickle/boron/chromium coatings, no ?
 
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@5Whiskey but that level porousness wouldn’t cause carbon fouling so bad that is a couple of millimeters in depth would it? 200 rounds of 5.56 shouldn’t cause carbon build up around the gas key and o-ring on the bolt that is so think that a normal brass brush can’t scrape it away. I had to grind the carbon off with a dental pick and then sit there for a long while with several brushes to just get the bolt clean enough to not bind or stick in the carrier. Even the firing pin needed thorough attention since it did not want to fall out freely like it normally it would due to how dirty the gun was.

Honestly, I’m impressed my particular rifle didn’t have more malfunctions than it did given the state it was in when I took it apart.
 
200 rounds of 5.56 shouldn’t cause carbon build up around the gas key and o-ring on the bolt that is so think that a normal brass brush can’t scrape it away.
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OK, attention to detail on my part... I missed the part about the build-up on the bolt and carrier. Yes that would have nothing to do the "carbon sweat" phenomena. That's called... it probably wasn't cleaned after the last class (or two).

Honestly, I’m impressed my particular rifle didn’t have more malfunctions than it did given the state it was in when I took it apart.
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M4s are quite reliable. I have seen carbon build-up behind the gas ring of the bolt that was so bad I could make a pretty nice sized pile of the scrapings. I almost wished I would have had my small digital scale to weigh it it was so much. Rifle still ran like a top.
 
Put together your own cleaning kit, and add carburetor cleaner to it, it really saves a lot of work. A big bottle of Rem oil, or something like that, should work wonders.

"Me and about 4 others in my group commented on this and the instructors stated that the rifles are cleaned after every range session, however, due to the porous nature of the metals, carbon seeps into the metals and after they sit for a while, they come out and combined with firing close to 200+ rounds per student, their carbon fouling is quite bad by the end of the day. They get not nearly every day, so the issue just keeps getting worse and never has a chance to clear up."

The instructor made that up, IMHO.
 
Most of our cleaning kits were lacking even the most basic cleaning supplies and we were supplied with a small dallop of CLP
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That makes life difficult. It also begs the question of how clean do they think you can get them without a decent kit?
they come out and combined with firing close to 200+ rounds per student, their carbon fouling is quite bad by the end of the day
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200 rounds between cleaning should not carbon up an AR, unless you are shooting frangible ammo or blanks. I'm guessing the frequency of cleaning was grossly overstated, or the cleaning kits just don't do much.

I've personally shot 1,500+ rounds through an M4 with just a few drops of oil at about 800 rounds during a get low and dirty class with the only stoppages being those induced for the class. I know plenty of others with similar experiences.
 
Kimio said:
These had to be some of the most filthy M4’s I have ever seen. Even more so than the M16 A2’s that I practiced with back in BMT. The rifles looked like they hadn’t been touched at all since the last 2-3 range sessions they’d been through.

Most of our cleaning kits were lacking even the most basic cleaning supplies and we were supplied with a small dallop of CLP to clean both the bolt and Barrel, which is clearly NOT what was needed to get these rifles cleaned up properly (good enough to keep going is the goal I suppose). The cleaning brushes and rods looked ancient and likely wouldn’t provide a good cleaning to the bore even with 4-5 passes due to the wear and tear I saw on them.
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Sounds like the culprit is substandard cleaning gear coupled with little to no inspection when turning the weapons back in. Even when complete and functional, the cleaning kit that fits in the buttstock of the rifle is pretty basic and needs to be replenished with consumable things like patches, CLP, etc. A good armorer is going to provide additional cleaning supplies like rags, q-tips, CLP, etc. if he wants the weapons to be really clean.
 
I know a guy who ran his AR until it began to act up.

2000 rounds as I recall. No where near the level of crud being reported.

Really badly run operation and disregard for the basic of whats supposed to be trained for, take care of you gun.
 
I know a guy who ran his AR until it began to act up.
2000 rounds as I recall. No where near the level of crud being reported.
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There was a thread on TFL about 10 years or so ago where the poster shot his AR about 20,000 rounds IIRC without cleaning just to see how long it would keep running. Any malfunction was treated to a little CLP, then back at it. I have had ARs come into the shop that had never been cleaned (no mention of number of rounds) and the upper and bolt carrier were molded to fit in carbon. They still ran fine. 10 minutes in the ultrasonic and back to normal.
 
I'm guessing the frequency of cleaning was grossly overstated
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Yaa think??? I think the OP's group just drew short straw and lucked out.

Personally, my AR carbine has about 3000 rounds through it and I haven't cleaned it. Just a squirt of CLP in the bolt and off I go. Having said that, I do pull the bolt to inspect it every so often and I've not seen anything like the OP describes. Even in Army basic training... lots of blanks, lots of full auto fire... they were never that bad.

Ha! Back in Basic I would have given my left arm to have a CAT M4 or any bolt scraper tool!!!
 
Hrm, Midway discontinued the G&G Tool.

I see that Brownells sells something called
OTIS - 5.56 B.O.N.E TOOL

Youtube has a demonstration of the tool and it looks good.
 
When I was in the Army decades ago you could not turn it into the armory until the standard of rifle cleansliness was met. I remember large groups of soldiers out on the sidewalks of the armory performing that remedial cleaning. I found that all armorers were pretty much universal in this regard. If the standard wasnt met you couldnt turn it in. This aspect kept me from ever liking or enjoying that particular rifle...
 
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