Cleaning Your AR-15 is Pretty Much a Waste of Time

I’m not the first person to say something like that.

I’m definitely not the most experienced AR shooter to say something like that (Recently, Mike Pannone published an article called “The Big M4 Myth” regarding fouling. I don’t want to claim any of his ideas as my own. If you see something that seems really intuitive, it probably came from him. In this article, I’m going to talk about the same subject, but with a slightly different approach).

And yet, the “clean your AR-15” mantra is repeated over and over, in gun stores, online, at shooting ranges, in military training, and so on.

Over the past few years, I’ve fired a number of ARs (and a number of other weapons, for that matter) for thousands of rounds without any sort of cleaning whatsoever – in most cases, I just kept adding lubricant to the weapon. Recently, as you can see right below this post, I fired close to 3000 rounds through a 5.45 AR-15 without cleaning or lubrication.

“But how?!” you say. “The AR-15 ‘defecates’ where it eats! I know this because people on the internet have been saying it!”

Well, I don’t want to spend too much time describing how the AR-15 works – Steve at Adco Firearms does a pretty darn good job here.

Self Cleaning?

What’s important to know is that the bolt is itself a piston – it even has rings just like the pistons in your car’s engine (unless you’re a Wankel fan). In other words, those rings need to have a good seal against the cylinder walls – the bolt carrier.

Every time the weapon is fired, the rings scrape carbon away from the carrier – the same goes for the bearing surface farther forward on the bolt (with the exception of the extractor, which must have room to maneuver, and therefore cannot serve as a bearing surface). Practically no carbon will build up on the areas where these components actually touch, even after thousands of rounds have been fired. This goes for the bolt carrier, too – where it contacts the upper receiver, it will be clean to the point that it appears polished.

Here are some photos to explain what I’m talking about:

Take a guess as to where the carrier contacts the upper receiver.

The contact points on the carrier are clean. Pretty much everything else is filthy. No big deal.

See all that carbon? Its presence is essentially inconsequential to the operation of the weapon.

It’s a bad photo, but you can clearly see the path traced by the extractor – rather, the path of carbon left where the extractor rides just beneath the forward bearing surface on the bolt. This bearing surface removes carbon from the rest of the inside of the carrier.

Here we see a very clear delineation between where the gas rings seal against the bolt – and where they do not.

What does all this mean?

Quite a few people are worried about carbon buildup. There are even companies that will sell you carbon scrapers – and of course, there are companies that will sell you an external piston/op-rod setup. Both have major drawbacks. Excessive cleaning can remove finishes which are important to the operation of the weapon. And eliminating the inline operating system, the “internal piston” as Armalite calls it, has a host of drawbacks that I won’t cover here and now.

The bottom line is that cleaning for the sake of reducing malfunctions is a waste of time. Cleaning may make the weapon prettier, cleaning may make you feel better – but cleaning will not drastically improve the reliability of the weapon, unless unrealistically large round counts are being considered. Even then, you would have a better chance of improving reliability simply by adding lube to the weapon, as shown by the single drop of oil in the cam pin hole of the 5.45 allowing the weapon to run for another 150 trouble-free rounds.What’s easier in the field – some lube, or a complete detail strip and scrape of every part with carbon on it?

There are reasons to clean your weapon, though – such as the corrosive primers used in surplus 5.45 ammunition, for example. Good finishes and metal treatments such as nickel boron and melonite should reduce this need, but only time will tell if it’s been eliminated.

Some people say that their AR only works when it’s perfectly clean. I say that if so, there’s something else wrong with the weapon. Some part is probably worn out – a spring, the gas rings, and so on – and needs to be replaced. Read Mike Pannone’s article for more information on that subject.

If your AR-15 is properly lubricated, and it’s malfunctioning, fouling is NOT the source of the malfunction.



Filed under AR-15

29 responses to “Cleaning Your AR-15 is Pretty Much a Waste of Time

  1. Dan

    I have to say that I consistently enjoy reading your articles. It is refreshing to see people who have an opinion and can back it up with an example. I have tired of the whole “DI is unreliable” nonsense. I am not going to knock gas-piston systems, but I don’t know of a single AR carbine class where the instructor uses an AR gas-piston rifle. The weapon wasn’t designed for it (carrier tilt anyone?). If you are going to use gas-piston, then the rifle should be designed for it from the ground up. Too bad Bushmaster screwed up the ACR.

    • Zoobster

      I have no clue how AR-15s work – but wouldn’t letting carbon build up in the “non contact points” reduce the effectiveness of rifling? The grooves need to be grooves to get the rifling effect – otherwise you’re shooting a very fancy muzzle-loader.

      • Andrew (Vuurwapen Admin)

        This morning I took the 5.45, which had never had the bore cleaned, to a 600 yard match. I shot a 179-3X (out of a possible 200-20X). The barrel was not free floated. 53gr surplus ammo was used.

  2. Josh

    Awesome post. My one question is how often should the barrel be cleaned? I read once you should only clean a chrome lined mil spec barrel once you notice a decrease in accuracy.

  3. MrMaigo

    The AR is a smartly built platform. The only parts that are close together are generally high tolerance, lubed, contact points. Everything else has plenty of space to be covered in crap.

    Wouldn’t it affect lubrication though? I’d think carbon build up would wick away lube making you lube more and more frequently.

  4. John Jackson

    thanks for the testing, results and insights – I’m learning a lot

  5. Not true and dangerous advice for the working rifle.

    Twice I have seen rifles in carbine classes fail to lock due to carbon build-up on the flange of the bolt’s tail and its opposing surface inside the carrier. The amount was so great that it kept the bolt from telescoping fully into the carrier. All that scraped carbon goes somewhere unless the AR/M design violates the 1st law of thermodynamics.

    One rifle was shooting Black Hills exclusively as a duty load and the other was running “whatever’s cheapest.’ Both rifles were back on the line after piece of 7.62X51 brass as a scraper.

    That said, I don’t see the need for a dedicated tool when a USGI chamber brush and a pocket knife work fine.

    • Andrew (Vuurwapen Admin)

      There must have been an exceptionally abnormal amount of carbon, or something else was the root cause of the malfunction. Even at 3000+ rounds, the bolt of the 5.45 weapon in question still has full and free travel. I have seen weapons with far higher round counts than that – they still had free & full travel in that regard.

      Please provide more details on the malfunctions and the actions taken. Was the only action by the shooters to scrape the carbon away, or did they lube the weapons as well?

      • I scraped off carbon off and ran a reamer into the bolt carrier. A failure to lock is exactly that, a failure of the bolt carrier to go fully into the battery position.

      • Andrew (Vuurwapen Admin)

        So no lubrication was added to the weapon at all? To not do so would seem an odd response to a malfunctioning AR.

        A “failure to lock” would seem to refer to a “failure to lock back.” The malfunction you describe is more commonly called a “failure to go into battery.” That is the malfunction I experienced after 2778 rounds (watch the video immediately below this post) with no cleaning and no lubrication. I added one drop of oil, directly onto the bolt at the cam pin area, and the weapon experienced zero malfunctions after that – I proceeded to fire 150 rounds as fast as I could pull the trigger and swap magazines. If you require proof, the entire thing is on tape, and it’s quite clear from the current condition of the bolt carrier group that I did NOT scrape any carbon away from those components.

        I say again, if the weapon is properly lubricated, and the weapon is malfunctioning, fouling is NOT the source of the malfunction. As to your comment on the creation and/or destruction of matter, the area you refer to does have two vent holes. When push comes to shove (and tens of thousands of pounds of pressure are involved), excess carbon will be forced out of those two holes. Carbon will not build up in that area indefinitely.

        Note that the point of my article is not that the weapon will function indefinitely without cleaning OR lubrication – only that lubrication is not required for thousands and thousands of rounds. Friction caused by carbon buildup is not a factor in the performance of the weapon until several cases of ammunition have been fired. At that point, the faster and more efficient manner of returning the weapon to service is to add lubrication to the contact areas. Scraping all the carbon away from the weapon takes more time and more effort. It requires breaking the weapon down to small components that can be easily lost in the field. Adding lube to the BCG takes seconds and does not expose the user to the loss of any small parts. It WILL, without exception, return the weapon to service.

    • willardcw4

      I’m not really sure how the first law of thermodynamics (which deals with the conservation of energy of a thermodynamic system and its surroundings with regards to internal energy, work, and heat transfer) can be applied to a macroscopic view of carbon and fouling being carried through a gas-impingement AR-15 system.

      However, I do agree with the write-up in that, if the weapon is not malfunctioning and lubrication is applied in a reasonable fashion, cleaning carbon and fouling may often be not as a high priority to ensure the proper functioning of the weapon system as most people think. I’d be more concerned with worn gas rings than carbon build-up on the end of the bolt tail.

      I am curious how cleaning the barrel (chrome vs. non-chromed) could change the performance of the rifle in a variety of circumstances.

      • Energy equals Matter. Matter cannot be destroyed only changed. The fouling that is scraped off by the bolt rings ends up somewhere.

      • willardcw4

        Yes, conservation of mass/matter… but you are assuming that the fowling ends up in a place inside the weapon system that will induce failure. I think what Andrew is saying is that, based on the way the weapon operates, up to a certain point, the system will be pushing and moving the carbon / fowling into places inside the BCG and upper that do not interfere with the weapon’s performance (to a point, of course).

        The fowling that ends up in the barrel, top of the upper, walls of the BCG, buffer tube, pistol grip, etc. (being hypothetical) would affect the weapon in different ways, or not at all. There is a lot of gas, carbon, and fowling that is blown around the upper receiver, but even more out of the end of the barrel.

  6. The big issue is to get over the garrison mentality that a well oiled rifle equals a dirty rifle. This counter-productive idea was mentioned as problem as far back as the Spanish-American War by notables such as John T. Thompson.

    It is ironic that the Army is now coming around again to recommending the use of more lubricant. After the well-publicized problems with the XM16E1/M16A1 in 1967, new instructions were sent out to field units to use additional lubrication, along with switching from the light VV-L-800 to the thicker LSA.

    Now heavy lubrication can be an issue when someone takes the idea too far and lubricates everything, including his ammunition.

  7. Correction: John T. Thompson’s quote actually predated the Spanish-American War, and referenced user feedback on the Krag rifle.

    “Attention is respectfully invited to Captain Leefe’s suggestion of a metal oil bottle. The magazine rifle is a small machine demanding more intelligent care from the soldier than the Springfield rifle. Certain working parts must be kept lightly oiled. The old idea that the soldier’s piece must not show, at inspection, any signs of oil must give away to the necessity for keeping these parts lubricated.”

    • Andrew (Vuurwapen Admin)

      Amazing. That mindset (oil is bad) has been passed down from generation to generation in the military, and it’s the source of a lot of problems.

  8. Have it your way folks, ignore my 2o years of working (building and teaching) with this platform professionally in favor of an anecdote.

    • Andrew (Vuurwapen Admin)

      Your information is no less anecdotal, and is not supported by the video evidence I have, showing that even when friction from carbon does cause malfunctions, lube is the answer. You did not answer my question – did you add lube to those two rifles?

  9. Redchrome

    Thanks for the link to the Mike Pannone article. Much of the stuff I knew already, but is new to a lot of people.

    What I take away from this article, plus my experience being an instructor at an Appleseed shoot immediately after reading this article (where I saw a couple of reasonably clean ARs with failure-to-go-into-battery and failure-to-extract problems with Wolf steel-cased ammo) is:

    * The AR platform can be made reliable under some conditions (proper gas dwell time, proper buffer weight, good quality spring, brass-cased good quality ammo, appropritate lubrication).

    * Carbon fouling isn’t as bad a problem as some would have you believe.


    * The carbon fouling doesn’t help anything.

    * I want a gun that isn’t so temperamental. The AR18 is basically an existence proof (from the mid 1960s) that a lot of things on the AR15 could be designed better. A Glock pistol can run for tens of thousands of rounds without cleaning (and possibly even without lubrication, tho like anything it wears out less quickly with it). I wonder how long a SCAR, XCR , or AK47 will run without cleaning or lubrication?

    * The length of time that things will work under good conditions (clean, good springs, brass-cased ammo), is an indicator of how well they’ll work under poor conditions (dirty & rusty because it was smuggled under a cart of manure to a freedom fighter, then buried under the floorboards for years, lubed with motor oil and put into action). Things just break down faster under bad conditions.

  10. Redchrome

    I should point out that the ARs I saw with problems running steel-cased ammo were in 5.56×45. (I’ve seen M14s fail to function after several hundred rounds with steel-cased 7.62×51 as well). Ammo better designed for reliability like 5.45×39 would probably be much more likely to run even under bad conditions.

  11. Aaron


    Thank you for this awesome post.

  12. wehrwulf

    I think when discussing the issue of Ar15 failures one should preface whether steel case or brass case 5.56 X -45- is used.

    Steel case 5.56 is study unto itself, no?

    Then there are slow burning powders? More carbon -will- be deposited. Whose ammo is cleaner?

    I would love to see this test repeated with steel 5.56 and brass 5.56 and -then- compare round counts and failure modes to the 5.45 steel of Andrew’s test.

    In all cases, as mentioned, keeping the gun (any gun for that matter that deposits carbon on critical working parts) “wet” with lube not only helps lubricity but keeps carbon in suspension. Motor oil additive packages have to deal with combustion by-products. So should gas guns………..especially ones fed steel case straight walled cartridges. This is beyond question.

    BTW, the Germans knew what they were doing when they designed the 7.92mm Kurz:-) The Russians apparently thought so too.

  13. Tim D.

    I cannot express how re-assuring this post (and others like it) is. In time, maybe these myths about the AR15 will simply fade away. Keep up the good work Andrew.

  14. mark

    Too much basic in my head to leave it go dirty, but as a unit armorer I considered running blanks as an extreme example of fouling and we couldn’t get more than a few mags run through before multiple failures. It would sort of work but not cycle well. I never had to clean those so I didn’t inspect until they came back fairly clean to compare to what you ran into. We certainly never told anyone to add any lube, would that have helped?

  15. Cephelo

    It takes a special kind of silly to suggest that a weapon system, *any* weapon system, does not need regular cleaning and lubrication for optimum reliability and performance.

    Just because you can get away with not cleaning your weapon for extended periods; doesn’t mean that you *should*.

  16. BAC

    Great article. First, I am a novice when it comes to this system so please bear with me. This system was originally designed with a 20″ bbl. and corresponding gas tube. What problems have been created by creating the M4 which I assume was not contemplated by the original designer? Is a mid length system a better compromise? My current rifle is a rock river upper 5.56 chrome lined mid length. Should I consider any modifications to the extractor, spring and buffer? What other modifications would you recommend? Thank you.

    • Andrew (Vuurwapen Admin)

      Well, the M4 tends to cycle a little faster, and because operating pressures are higher, parts tend to wear out faster. It can still be made to operate just as reliably, however.

      I do think that the midlength is a better compromise. If your rifle is working right now, chances are that nothing needs to be changed. If the gas port is an appropriate diameter, and the chamber is 5.56, a midlength should not need extra power extractor springs or heavier buffers to perform reliably. There might be room for improvement, though.

  17. Thanks for a good article. I had read this info elsewhere. Thanks for the info.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s