How To: AR-15 Barrel Installation

Hello everyone! We are back and this time Team Clevenger is taking you to school! Well not really….

Most gun owners feel attached to their guns, every piece and part! But eventually those pieces and parts need replaced, or better parts need to be installed to make your gun run even better. Well Heath and I recently received new Criterion Barrels, so you can imagine how excited we were to get these new barrels installed! The thing is, I have no idea how to do that! I’m not even sure what parts you need, or even what some of the parts are or what they do. Luckily for me, my amazing husband does and was willing to film a video on how to install your new [Criterion] barrel into your AR-15. A task that may seem simple to people who have been shooting and working on guns their whole lives but may not be that simple to new shooters like me. Best way to learn is to have someone that is willing to teach you, and Team Clevenger is here to teach you.20150228_112045First here is Heath to give you a quick step by step explanation with pictures.

Heath: “First you will need the right parts. Today I worked with the receivers that I pulled the old barrels out of and I am  replacing them with Criterion hybrid contour 16.5 inch barrels with a mid-length gas system. I will be using a Syrac adjustable gas blocks, and new gas tubes on both rifles. I will be reusing the free float hand guards, and the Miculek Compensators for these rifles. I completed two builds, one had pictures taken during the build, and one we filmed the actual build. So, each gun had a different hand guard. One rifle has a Troy hand guard and the other has a Samson. Both are quality products and have held up to years of [ab]use.

Also, I like to check the headspace in the barrel prior to installing the barrel into the receiver. You will need at least a NO GO headspace gauge. The NO GO is the one to worry about. Take the bolt out of the BCG and place the NO GO gauge in the bolt. Then attempt to “chamber” the gauge and turn the bolt in the barrel extension. If it turns, then you have a problem. If you have access to the GO gauge, you can check it but I generally only worry if it is not going to work. If it fails, you will need to see if the bolt is the problem or the barrel. If you use quality parts, this should not be a problem.


Step one: Put the upper receiver into the vice block and secure it into the vise. Take some gun oil and lube up the receiver extension and the barrel extension. This will allow the barrel to slide into place easier and give you reliable torque specs when tightening the barrel nut later. Also, when it comes time to pull the barrel out of the upper receiver, it will come out easier. Next, put some grease or anti-seize on the barrel nut threads. Again this will help with yielding the proper torque specs and disassembly in the future.

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Step two: Hand tighten the barrel nut on the receiver then get you barrel nut wrench and be sure it is properly set in the barrel nut. I begin with tightening the nut down to 60 ft./lbs. Then loosen the nut and retighten again. I do this three or four times to help set the barrel all the way into the receiver. Then I increase the setting on the torque wrench to 70 ft./lbs. I set the gas tube into the upper receiver and over the notch in the barrel nut that will line up under the gas tube hole in the receiver. As I do the final tightening of the barrel nut, I watch the gas tube to be sure it is perfectly aligned with the gas port in the barrel. If the barrel nut pushed the gas tube to one side or the other, it will cause premature wear on the gas tube. If you are running an adjustable gas block with the gas cut down, then you could have some failure to cycle sooner rather than later. A competition gun has to be reliable.


Step three: Take your gas block and install it onto the barrel. I prefer the one with the set screws in the bottom of the gas block. That helps keep the block pulled down on the barrel to prevent as little gas escape and possible from happening between the gas block and the barrel. Criterion has the barrel cut on the opposite side on the gas port to make sure that your gas block is aligned with the gas port. Not all barrel companies cut that in for you, and it is a big help to the guy putting his own rifle together. I put blue Locktite on the set screws to keep them from backing out. This is another area of the rifle that gets real hot during shooting. Any screw on a gun will come unscrewed eventually, given enough time and shooting without some sort of lock on the screw. Now insert the gas tube into the gas block. Be sure that you slide the tube all the way into the gas block and get the hole in the tube lined up for the roll pin installation. Then take your roll pin punch and get the roll pin started. Never hit a pin with a hammer, ever. Always use a punch. It helps protect the pin. Then take a larger punch and finish putting the roll pin all the way into the gas block. I like to tape up the end on my larger punches to keep from marring up and leaving marks on my parts if possible.

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Step four: Almost done. Install the free float fore rail on the rifle. I like to take scope mount or old A2 style carry handle to make sure the rail and the upper receiver are perfectly aligned. (I prefer the 15 inch length rails to help make sure the barrel does not come in contact with any barricade during shooting. It also allows the shooter to get the support hand out as far as necessary to the end of the barrel during shooting to control the rifle.)

20150228_110958 20150228_111124 20150228_111128 20150228_111135 20150228_111215 20150228_111239 <— You will need tighten up your rail onto the barrel nut. Follow the instructions of your rail manufacturer. I am installing a Samson rail in the pictures above.

Step five: You may want to tape up the end of the barrel just before the threads. This will protect the barrel finish during the install of your flash hider/ compensator. Just another thing to help your rifle look good, along with preforming well. Install the flash hider or comp. Some flash hiders and comps come with a crush washer. Crush washers are only good for one use. The Miculek Comp uses a lock nut. I apply a little blue locktite on the barrel. This helps the comp from unscrewing over time. The lock washer is used by adjusting the comp into position and then tightening the nut against the comp. The crush washer applies pressure to the comp/ flash hider to prevent it from unscrewing.

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Now you are ready to head to the range and sight in your new upper receiver.”

Still need a better explanation? Well lucky for y’all we made an informative video.

The barrels used come from Criterion Barrels a manufacturer located in Wisconsin. They were initially a division of Krieger, Criterion is now a completely separate facility, with over 30 years of experience and expertise. They manufacture quality button rifled barrels. Criterion offers a complete lineup of rifle barrels to include classics such as M1 Garand and 1903, Tactical models for AR pattern rifles and the M14, and a custom line dedicated to OEM and match shooters.

Thank you again for checking us out If you want to see another video or have any questions, please feel free to make suggestions and ask any questions. We want to help.

Thank you,
Niki and Heath Clevenger

“Whatever your hand finds to do, do it with all your might”- Ecclesiastes 9:10


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