Installing a Barrel on Your AR 15

Installing a Barrel on Your AR 15

Installing a Barrel on Your AR 15

If you’re interested in firearms, building your own AR 15 is an experience that you may have been thinking about for quite some time. It’s exciting, rewarding, and if you have the right set of instructions in front of you, not very difficult!

One of the most important parts of the AR 15 building process is the AR 15 barrel install. Knowing the right way to install an AR 15 barrel is crucial if you want a functional gun that’s safe for use. If you’re looking to learn how to install an AR 15 barrel the right way, you’re in luck, because we’ve put together an all-inclusive guide!

What Tools You’ll Need

If you want to undergo any task, you’ll obviously need the right tools to get the job done, and installing an AR 15 barrel is no different. Here is a list of tools you will need to sure you have on standby so that you can get the job done:

  • Upper receive fixture: Choose something with a “pins”-style block to give easy and clear access to the upper interior and make the gas tube alignment checks easier.
  • Barrel nut wrench head: If you can, find a barrel nut that engages full-circle, as most are half-circles. Look at the hand-guard rail you chose and pick something that aligns with that barrel nut.
  • ½” drive torque wrench: Opt for a bigger wrench if possible.
  • ½” drive breaker bar
  • Anti-sieze: Can be found at an auto parts store — this is an important tool to prevent galling and corrosion.
  • Gas-tube alignment tool

Installing the Barrel

Now that you have all the tools you need and all the parts of the AR 15 barrel, it’s time to install your AR 15 barrel. Follow these steps with caution and be sure to double check your work — remember, safety always comes first when firearms are involved.

Step 1: Fit the Barrel

Set up the upper so that it’s fixed into whichever fixture you choose.

  • Wipe down the soon-to-be-mated surfaces to remove any debris or residue on your barrel.
  • Locate the pin on the barrel extension that fits into a corresponding slot on the threads around the barrel extension receptacle within the upper.
  • Seat the barrel into the receptacle — it should slip back and seat fully. If this isn’t the case, the barrel nut will seat it later on.

Using the anti-seize, put a thin, even coat on all the receiver threads. Many people choose to use a flat artist’s brush to do this.

Step 2: Seat the Surface

Get a barrel nut (whichever you have on hand).

  • Fix the wrench head onto a breaker bar so that you don’t have to use a torque wrench to loosen.
  • Run the barrel nut on and tighten it firmly. Yank the barrel nut, back it off, snug it down again, and repeat.
  • Try to take it to at least 35 foot-pounds during the install.

This process is called “seating the surface” and is a form of mating that will face down any surface imperfections on the receiver.


Using your torque wrench, install the wrench head. Tighten the barrel nut until the wrench clicks — only do this once though! Repeated clicking means you’re going too far.

Using either the scallops on the barrel nut, a passage on the barrel nut and the passage through the upper receiver, set up the gas tube so that it’s dead-center through this path.
It’s important that it’s dead centered through whatever it passes through so that it has a clear line down the firearm.

Remove the bolt assembly from the bolt carrier and insert the gas tube alignment tool into the carrier key.
Put the works into the upper and push it forward as far as you can.
Now, you need to decide how much torque to put in your barrel nut? The 35 foot-pounds one usually works well, but you may need to tinker a bit to get different results.

Double-check to make sure that the gas tube is perfectly centered.
Use anti-seize if you need to in order to adjust any structural damage.
The tube should rattle a bit (with free and equal movement all around), but if it’s binding, be sure to adjust that.

Once the tube is installed, move the carrier in and out so that the key is fully engaged in the tube and listen for any movement in the tube. If you don’t hear any, you have successfully installed your AR 15 barrel.

Install your Barrel the Right Way!

All in all, the most important thing to do when installing your AR 15 barrel is to do it carefully. As with anything having to do with a firearm, safety is the utmost priority. Take the time to do it right now so that you can rest assured that everything will be ready to go when you take the weapon to the field or range to shoot it. It’s always better to be safe than sorry! Adding a suppressor into the mix can elevate your AR 15 even further.

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