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Keeping the AR-15 (and M4 carbine) gas system running.

Posted by: Grant Cunningham






I’m constantly amazed at the number of people who believe that the gas impingement system of the AR-15 rife and M4 carbine is
somehow a liability. So strong is this belief that there is today a growing subset of the industry making good money by adding parts to the
original Stoner design in a misguided attempt to “ x” the “problems”.


Over the years (and many tens of thousands of rounds) I’ve not found the gas system of the AR pattern rifles to be of any kind of issue.
Mike Pannone recently wrote a good article about the misconceptions surrounding the gas impingement system, and his long term test to
prove them wrong, over at Defense Review. I recommend that you read the article, as his observations generally mirror mine (with the
exception that I’ve not found it necessary to modify my Colt Carbine, which has proven completely reliable in the nearly 20 years I’ve
owned it.)


Many complaints about the gas system concern the reputed tendency of the gas tube to clog, which I don’t doubt has occasionally
happened. The way to avoid that is to never clean the gas tube!


Lots of shooters will put bore cleaner down the gas tube and swab with one of the gas tube brushes available. This is the start of the
problem, as you can never completely swab out the cleaner. As soon as hot gases are introduced during the ring cycle the remaining
petroleum turns to carbon and adheres to the walls of the gas tube. Repeated cleanings simply add to the deposits.


When I get a new ri e I take a gas tube brush and use acetone or denatured alcohol (acetone works better) to clean out any oils from the
gas tube, then I never touch it again! You can run a brush down the tubes on my rifles and it will come out clean. The gas tube is designed
to be self cleaning, and as long as you don’t soil it yourself it will do its job.


At the other end of the tube, where the gas contacts the bolt carrier to drive it during recoil, is the other source of misplaced concern: that
the gas system fouls the bolt and causes stoppages (“it defecates where it eats” is the nonsensical refrain, usually stated a bit more
colorfully than I have.) I’ve never found this to be a problem either, and again it comes down to proper maintenance.


Many people are of the impression that the gas relief holes in the bolt carrier are for oiling the bolt. Resist that temptation! Oil down those
holes gets into the gas rings and onto the back side of the bolt, where the hot gases quickly turn the oil into carbonized sludge.


I prefer to lubricate the bolt head in front of the gas rings, on the little ridge that runs around the bolt head and serves as a contact point
in the bolt carrier. I prefer to use a light, non-tackified grease (food grade NLGI #0, such as Lubriplate SFL) on just that ring as well as on
the locking lugs themselves. There’s no need to lube the rings or any surface on the back end of the bolt.


A little of that same grease on the contact rails of the bolt carrier and you’re done. The AR-15 bolt assembly needs lubrication to function,
but doesn’t need to be dripping wet.


How reliable are my rifles with this regimen? A couple of years ago I spent several dry, dusty days at a range in Fernley, NV. The earth from
which the range was carved was not sandy; it was very much like talcum powder. The dust got into everything (including the pores of the
green plastic furniture on one of my guns, which to this day I’ve not been able to thoroughly remove.) During that time several of the guns
malfunctioned, including a SIG 550 (or is it a 556? I can never remember their nomenclature.)


Both of my rifles ran without any attention, to the point that several other participants preferred to borrow my guns rather than trust
theirs when time for the end-of-course shooting contest came around.




4/7/2019 Keeping the AR-15 (and M4 carbine) gas system running. - www.GrantCunningham.com www.GrantCunningham.com


www.grantcunningham.com/2013/12/keeping-the-ar-15-and-m4-carbine-gas-system-running/ 2/3





The direct impingement gas system is as reliable as any other when understood and maintained appropriately. I’ve not found it necessary
to be anal retentive in doing so, either; I don’t spend a lot of time cleaning them, because most of the parts are self-cleaning by design
unless you do something to mess them up. Learn how the system works, understand where the contact points are and make sure they’re
lubricated, and your AR-15 will likely work as well as mine do.


-=[ Grant ]=-
 

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Interesting article, thanks for posting!

Despite Uncle Sam’s insistence that we keep our weapons in a near-surgical state of cleanliness, the gas tube was left alone. We never touched them. In regards to lubrication, my experience in the big sandbox across the pond mirrors Mr. Cunningham’s... keep the lube to a minimum, and put it in the proper spots. While I agree that there are pros and cons to both DI and piston-driven systems, I personally prefer the lighter weight and simplicity of a direct impingement setup.
 

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I've been shooting ARs since the early 1990's. I've never cleaned or found a need to clean the gas tube.
 

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I went as far as buying a pack of those long pipe cleaners intended for the gas tube (I've had this AR for decades, shorely the gas tube is dirty), ran it through, and it came out as clean as when it went in.

Never messed with the gas tube in the Army. I am also a "light amount of lube" maintainer. Not a believer in an AR having to be drenched to run. I will admit to running one wetter than I normally do recently; shot my first 2-gun match and it was a brand new build... ran fine.

If anyone needs one of those pipe cleaner thingies I have a few extra LOL...
 

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Interesting article, thanks for posting!

Despite Uncle Sam’s insistence that we keep our weapons in a near-surgical state of cleanliness, the gas tube was left alone. We never touched them. In regards to lubrication, my experience in the big sandbox across the pond mirrors Mr. Cunningham’s... keep the lube to a minimum, and put it in the proper spots. While I agree that there are pros and cons to both DI and piston-driven systems, I personally prefer the lighter weight and simplicity of a direct impingement setup.
Unit Armorers can be real dicks. Never cleaned a gas tube in my life and was handed my first M16 in 1976.
 

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I'm glad to learn my laissez-faire attitude toward gas tube maintenance is the preferred course of action. I built my first AR during college because I thought it would be a "cool" rifle to have. As I become more familiar with the platform, I'm enjoying learning about how well-designed the platform is.
 

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I have a tube of food grade grease I use on bcg but grease in lower is a no go for me . There I use synthetic Castor oil .

Sent from my Moto E (4) using Tapatalk
 

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Keeping the AR-15 (and M4 carbine) gas system running.

Posted by: Grant Cunningham
I’m constantly amazed at the number of people who believe that the gas impingement system of the AR-15 rife and M4 carbine is somehow a liability. So strong is this belief that there is today a growing subset of the industry making good money by adding parts to the
original Stoner design in a misguided attempt to “ x” the “problems”....
-=[ Grant ]=-
There is a prevailing way of thinking with US firearms enthusiasts that goes something like:

  • "if Eugine Stoner designed it that way, he did it for a reason"
  • "if it’s good enough for Uncle Sam, then..."
Supporting that logic, is the fact that the DI system actually works really well, and it is very reliable when a certain "regimen" is practiced to maintain it. Grant is telling us the regimen does not need to be as OCD as the US military trains. Based on my experience, I agree with these facts.

It is also the case; it is usually people who served in the US military that develop an almost fanatical devotion to cleaning their weapons. They accept that a rifle’s BCG and Bolt to get as dirty as a DI piston rifle as “normal”.

There are some of us who are better compared to a Somali militia when it comes to cleaning weapons. Or, we simply look at the design of firearms a lot more critically than others.

I think Grant’s point is why be bothered with a conventional piston in an AR? Why fix what isn’t broken? Consider this:

Eugene Stoner's approach to the AR15 was to line up all the kinetic energy inside the rifle in a straight axis with the bore, front to rear. The DI piston inside the BCG is part of that methodology. There are distinct advantages to this approach that include accuracy and alignment of recoil energies. There are also compromises and liabilities, and other designers of basic infantry weapons went with a more conventional approach. If keeping the action clean and cooler (relatively) are more important than sub-MOA accuracy, the DI piston inside the BCG is not the ideal approach.

Because the system works, and the system does work on a large scale for the United States military, we overlook those compromises because the way the United States implements these rifles it doesn’t really matter.

I would say that the DI piston system has its place. For instance, if I were to employ a highly accurate semi-automatic rifle to engage targets at 800 + yards, say in 6.5 Creedmoor, I would look at a DI AR-10 platform over a piston rifle such as a M1A(M14). This is a rifle that would not sustain a high rate of fire, would be utilized by a specialist who employed a maintenance "regimen" that was congruent with his high level of training and had a support network, and was fed fairly consistent, high quality ammunition. In a basic infantry rifle, the DI piston’s biggest liability is that it exceeds the point of diminishing returns in respect to the benefits it brings compared to overall additional complexity to maintain the system, feed it good ammunition, and spend time cleaning the inside of the BCG and outside of the bolt.

The long discussion about why the AR-15, DI BCG, and Piston are really cool.

The US got the M16 because Curtis LeMay thought it was cool. LeMay usually got what he wanted - and had an eye towards edgy kinds of technology whether they were DI rifles, SSB radios, or supersonic aircraft used to deliver nuclear weapons. He usually had good instincts in this regard.

I’m sure LeMay had considered that the United States military has world class logistics capabilities. The United States can bring the worlds industrial resources right to the battle field in a way no one else can. You need parts for rifles, no problem. You need to rebuild rifles in theater, no problem, we can even get contractors for that. Given this, what is important is that the rifle is 1) relatively inexpensive to initially manufacture 2) can be supported inexpensively due to modular construction so that any part can be replaced at a relatively low level, and 3) replaced in whole or rebuilt inexpensively when rifles are worn out, or need to be upgraded into new configurations. The United States does not need to employ equipment that has to endure the maintenance regimen of a Somali militia, and because of its logistical advantages can afford to employ relatively inexpensive weapons that are modular, practically disposable if need be, easy to maintain by replacing inexpensive, standardized parts. LeMay was a visionary.

The AR-15 is a good platform, but not without some issues. There are things that simply were not addressed because a high level of support was assumed. These are rifles that are intended to be worn out and replaced.

What is very cool about the AR-15 is all the corners that were cut - everything from bolt carrier key gouge in the upper receiver to carrier tilt are easy problems to solve. The speed of the bolt can be slowed down and it will even eat a steady diet of nasty steel cased ammunition without a hiccup. My AR builds are completely different animals that what is normally considered an AR-15 – both inside and out. Usually when people start shooting my rifle, they won’t give it back until they are out of ammunition. And yes, they use pistons and shoot 6.8 SPC with less felt recoil than a standard M4 shooting .223.

Why I think LeMay probably thought the AR-15 is coolis this. I think LeMay anticipated the AR-15 would evolve into something very different than the simple infantry rifle it started as. I think he saw that it is a completely modular platform and can evolve and morph into whatever it needs to be. We used to think of a rifle as a single “thing” with certain characteristics that defined it. The AR-15 changed that – it now defies its own definition and becomes whatever we need it, or what we build it, to be.

I and a lot of other people know how to address AR-15 platform issues in a manner that facilitates radical evolution of the rifle to more closely match the new requirements we have in mind. A piston is one thing some of us choose to employ to reduce the amount of gasses being vented into the action, reduce the temperature of the bolt and carrier, and increase the mass of the gas system. It also keeps the action cleaner and makes it easier to clean. For that matter, chambering the rifle for 6.8SPC is also one of those things.

Traditional wisdom was that if you wanted a piston driven self-loading magazine fed rifle in a short (5.56 sized) action, look towards a FNC, AR-18, T-65, Galil, etc. Traditionalists looked at the AR-15 as being defined by the DI piston in the BCG and not at all suitable for a conventional piston. Even today, gun blogs were full of talk highlighting perceived design problems making a conventional piston run in an AR – the writers focused on problems and not solutions, and either they were purposely omitting an intelligent discussion to bash a product, or they really are as dumb as they sound. That kind of thinking is not valid to people solve problems for a living. I’ve solved **every** problem ever written about AR-15 piston conversions, quite simply.

Today, we can take a single weapon platform, apply interchangeable parts created by industry, identify and define technical challenges and solutions, including those that change the very core function of the weapon, and employ all of this relatively inexpensively to create the rifle we need. LeMay’s vision has materialized. Yeah, it really is legos for guns.

Mikhail Kalashnikov, Hugo Schmeisser, Dieudonné Saive, Ernest Vervier, Wilhelm Stähle, Ludwig Vorgrimler, John Garand and Eugene Stoner all designed rifles that were widely adopted by armies throughout the world that are not DI. So what?

The US military uses DI weapons. They also use at least two conventional piston versions of the AR too. So what?

Gun writers and internet experts repeatedly show us how pedestrian their thinking is by coming out on the anti-piston bandwagon. Their thinking is too conservative. You are amazed because these people have a big voice in the gun forums and blogs and yet there are people who defy them. The danger of their mis-information or narrow vision is that people generally believe what they read, and follow like sheep. The industry only provides the parts and options that sell. These writers essentially are drying up a market by narrowing peoples vision with their short sighted, pedestrian drivel.
 

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After the US military had problems in VietNam they realize how dirty certain powders were. If they had used the powder Stoner had specified, we may have never had these conversations. Also interesting to me, Stoner designed the AR180 with the piston system after the AR15. Maybe he thought the DI system was a mistake? I do remember having to chisel off the carbon on the bcg while in the service.
 

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After the US military had problems in VietNam they realize how dirty certain powders were. If they had used the powder Stoner had specified, we may have never had these conversations. Also interesting to me, Stoner designed the AR180 with the piston system after the AR15. Maybe he thought the DI system was a mistake? I do remember having to chisel off the carbon on the bcg while in the service.
[Mr.Robinson'sNeighborhoodVoice] Can you spell McNamara? [/Mr.Robinson'sNeighborhoodVoice]
 

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In addition to the Vietnam era debacle, when Uncle Sam went cheap on ammo recipe, and neglected to include cleaning kits... there is another facet to the matter. We have not always had non-corrosive, smokeless powder. Anyone who shoots black powder understands the need to THOROUGHLY clean their weapon after shooting it, or start replacing rusted parts/weapons. Generations of our elders have beat into our heads, the NEED to keep a squeeky clean weapon... because it's always been done that way... often, with a "don't question what I say, just DO it" attitude. Well, back in the day, you DID need to keep it squeeky clean/dry/oiled. We didn't have anything fancier than blued finishes, and burned black powder residue trashed metal faster than moisture did.
 

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In addition to the Vietnam era debacle, when Uncle Sam went cheap on ammo recipe, and neglected to include cleaning kits... there is another facet to the matter. We have not always had non-corrosive, smokeless powder. Anyone who shoots black powder understands the need to THOROUGHLY clean their weapon after shooting it, or start replacing rusted parts/weapons. Generations of our elders have beat into our heads, the NEED to keep a squeeky clean weapon... because it's always been done that way... often, with a "don't question what I say, just DO it" attitude. Well, back in the day, you DID need to keep it squeeky clean/dry/oiled. We didn't have anything fancier than blued finishes, and burned black powder residue trashed metal faster than moisture did.
Yes, it was kind of a double edged sword. Dirtier burning powder and no cleaning kits. This is why when you see any of my personal ARs they are slick sides. Don't have any need for all those stop gap doohickies on my rifles.
 

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I remember when I first bought an AR-15, this dealer told me I had to buy pipe cleaners to clean out the gas tube... I still have a big bag of pipe cleaners somewhere, unopened.
 

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I remember when I first bought an AR-15, this dealer told me I had to buy pipe cleaners to clean out the gas tube... I still have a big bag of pipe cleaners somewhere, unopened.
Sell 'em to a libtard... he can clean both ears at the same time. :a01:
 

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Machines made of iron, steel, aluminum or similar like lubrication. In fact, they prefer it to be applied liberally. Adding a variable like a dust storm doesn't change that. The oil is contaminated and the only way to stop it is to seal it off, we can't, or use less lube for the dirt to stick to.
 
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