AR-15 Barrels | Explained

AR-15 Barrel questions answered - Thumbnail
March 6, 2024 Edited March 6, 2024 215 view(s)
AR-15 Barrels | Explained

How to clean an AR-15 barrel

We’ve all been there: a few hundred rounds down range, and our AR-15 barrel is caked with grime and buildup. So, what do you do about this disgusting buildup of grime, grease, and gunpowder residue?


And also, do you really need to clean it after every trip to the range? Let’s take a look at what it takes to keep your AR-15 barrels clean, what you should use to do the job, and even how to remove one if you really want to.

How often should you clean your AR barrel?

In a perfect world, you should clean your AR-15 after every use. But we don’t live in a perfect world. So, how often do you really need to clean your AR-15 barrel? Well, to be honest, there are some variables to consider. 

  • How many rounds have you put through it since the last cleaning?
  • What type of ammunition do you regularly run through it?
  • How often do you shoot it?
  • And how often do you take it out of the safe?

There is no downside to cleaning your AR-15 after every time you shoot it, so we suggest you do just that. Also, if you have questions about your specific firearm, consult your owner’s manual. 

How to remove an AR-15 barrel

One question that is often asked is how to remove an AR-15 barrel. First off, you don’t need to do this for routine maintenance or cleaning. 


If you do decide to remove your AR-15 barrel, you’ll need the following:

  • Upper receiver vice clamp
  • Barrel nut wrench, spammer wrench, or AR-15 armorer’s tool, depending on the type of barrel nut.
  • A workbench, preferably with armorer’s mats.
  • Standard assorted bits and driver for removing the hand guard and any other miscellaneous items.

Here are the basic steps:

  1. Install the upper receiver in a vice block and in a vice.
  2. Remove the hand guard.
  3. Remove the gas tube and gas block as a unit if possible.
  4. Remove the barrel nut (it may have set screws in it, so check for these first).
  5. Slide the barrel away from the receiver.

How to measure an AR-15 barrel length

Okay, this one is really important because it has strict legal ramifications.


AR-15 barrel lengths are measured without any removable accessories on them, i.e., the muzzle device. Now, if the middle device is pinned and welded into position, it does count toward lengths determined from the very end of the chamber to the crown of the thread portion of the muzzle.


Since the legal limit is 16” for a rifle or shotgun, this is the most common standard length, although you are free to get any barrel you want since they are unserialized. But beware that you must be able to make it a total of 16” from the end of the chamber to the end of the muzzle, which includes a muzzle device if it is permanently fixed. 


The old XM-177s are a great example of this. The muzzle device, called a moderator, is 4 ¼” long, so you could technically use a 12” barrel, pin and weld the moderator on, and be legal. Of course, that seems illogical since that reduces muzzle velocity and energy, but it does meet the letter of the law. 

What is the best thing to clean a rifle barrel with?

First and foremost, read your manual. The manufacturer knows exactly what to use.


Generally, a good .22 caliber bore brush will do the trick, and you can dip it in a good solvent like Hoppes #9 or CLP


The bore brush breaks loose powder and other stuff caches while the solvent neutralizes the burnt powder residue. Usually, you can get a piece of cloth and dip it in solvent to run down the barrel to catch the grime and then a dry one to pick up the residue. After that, I dip another clean cloth in gun oil (RemOil is my go-to) and run it down the barrel to lubricate it.


The bore snakes in the market also interest me. They make it so you can just pull the brush through the breach and down the barrel. This eliminates the need for cumbersome brass extension rods that are never seen to be the ones you need when you need them. IYKYK.

Should you oil an AR-15 barrel?

Should you oil an AR-15 barrel? I’d say yes. Guns don’t really require all that much oil, so be conservative. Just a very light film is all the barrel needs to be protected from the elements, corrosion from gunpowder, etc.


If you have questions about the specifics of your barrel or your AR-15 in general, consult your owner’s manual 

Is WD-40 good for gun barrels?

WD-40 is a lot of things, but it is not a gun oil. 


Don’t use WD-40 on your guns. If you have a rusty padlock, spray it with WD-40. If you need your bike chain to stop squeaking, spray it with WD-40. 


Gun oil is really cheap, and you can get it at all sporting goods stores or Walmart. Don’t even think about cheaping out and putting general-purpose lubes on a gun when gun lubes are readily available and don’t cost any more. 

What is the best oil to put on a gun barrel?

I hesitate to endorse any one oil to put on a gun barrel because the “akshually” reply guys will eat me alive. 


So I’ll just say this: use a firearm-specific oil. No general household or shop lubes. No silicone. My favorite is the old-school classic Hoppes #9 lubricant. I have never had a problem with it, and it is sold at Walmart. Why go fixing something that isn’t broken? The formula is the same now as it was around the turn of the 20th century. Do your own research and use whatever brand you like the best, but do not throw 3-in-1 oil on there or anything like that. Just get some good gun oil, and do not use it liberally. CLPs are dirt and scum magnets, so a very light, thin coat is all you need. 

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Francisco Solis
April 3, 2024
I have the 10.5" .556 complete upper and want to add a angle foregrip. The mlok doesn't have any where to mount one. What is a good quad rail to use it is a bca upper?
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