How to Align an AR Barrel Nut

How to Align an AR Barrel Nut

Gus Norcross, originally trained on National Match rifles and pistols by the National Guard Marksmanship Training Unit specializes in Garands, M14s and 1911s at his small shop on the coast of Maine. His website is www.angusarms.com. He will be offering gunsmithing tips and tricks on Fridays.

A properly installed gas tube should last for many thousands of rounds, but in the current market where everyone with a barrel nut wrench is building ARs in the basement, we should discuss the relationship between gas tubes and barrel nut alignment.

A slight misalignment between the barrel nut and the carrier key during assembly may cause premature gas tube wear and drag on the bolt carrier. The tip of the gas tube is enlarged slightly and nominal diameter should be .180".

A shoulder is present where the large end transitions to the smaller .170" main tube that can wear away on one side, causing gas leakage and short stroking. Check a suspect tube for this condition visually with a magnifier and verify proper diameter with a micrometer. Tubes that are bent during installation or cleaning may also wear unevenly.


Check barrel nut alignment by stripping the bolt carrier assembly and inserting a #15 drill or .180" gauge pin into the carrier key. Install the carrier and charging handle into the upper receiver and slide it forward until the drill protrudes through a hole in the barrel nut.


If the barrel nut is misaligned, the drill won't be centered and may not even pass through it. Adjust the position of the nut as necessary. I have seen upper receivers that had the gas tube hole drilled slightly off center but fortunately such defects are rare today.

Gas tube replacement is a simple task with the Mark Brown gas tube wrench, available from Brownells, but take care not to bend them on shorter gas systems where they have to be weaseled around a bit during installation. Operators firing full-power 5.56mm NATO spec ammo such as M193, M855 or MK262 may find a worn gas system less problematic than a civilian shooting .223 Rem. commercial fodder at lower pressure levels.

Gauge pin inserted

The .180" gauge pin is inserted into the gas key on the stripped bolt carrier.

Alignment

The pin protrudes through the barrel nut as the carrier is installed, indicating proper alignment.

Gas tube

The Mark Brown gas tube wrench firmly grasps the gas tube, making removal and installation much easier.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Springfield Armory Saint Victor in .308

Springfield Armory Saint Victor in .308

The Saint Victor in .308 features a 16" light weight barrel, M-Lok® free float hand guard and included flip-up sights.

Shooting the 20mm Lahti

Shooting the 20mm Lahti

David Fortier had the chance to fire the Lahti L-39 while filming the 2018 season of Guns&AmmoTV while on location at DriveTanks.com.

New addition to the Browning X-Bolt rifle series

New addition to the Browning X-Bolt rifle series

New for 2019 is the Max Long Range model featuring a composite Max stock with fully adjustable comb, spacers for adjusting length of pull, stainless fluted heavy sporter barrel, threaded muzzle brake and extended bolt handle.

New Bushnell Prime 1700 and Nitro 1800 Rangefinders

New Bushnell Prime 1700 and Nitro 1800 Rangefinders

Jake Edson of Bushnell Optics tells OSG's Lynn Burkhead about the brand new Prime 1700 and Nitro 1800 rangefinders.

See More Popular Videos

Trending Articles

Want the “Holy Grail” of AR-15 rifles? Brownells has made that possible with their BRN-Proto retro rifle. Rifles

Brownells BRN-Proto Retro Rifle

Patrick Sweeney - July 02, 2019

Want the “Holy Grail” of AR-15 rifles? Brownells has made that possible with their BRN-Proto...

No one can restore receptivity to another Trump term with these disaffected gun owners but the president himself. 2nd Amendment

2020 is Trump's to Blow with Gun Owners

David Codrea - July 09, 2019

No one can restore receptivity to another Trump term with these disaffected gun owners but the...

CRKT makes 17 different knife models exclusively for Ruger, from fixed hunting knives to tactical folders, and many of their models are offered in several different styles. Accessories

Ruger CRKT Knives Review

James Tarr - July 08, 2019

CRKT makes 17 different knife models exclusively for Ruger, from fixed hunting knives to...

Rhode Islanders are setting brushfires for freedom once again as they advance a Second Amendment Sanctuary Town movement. 2nd Amendment

SPECIAL REPORT: BIG 2A HISTORY BEING MADE IN LITTLE RHODE ISLAND

John Peterson - May 22, 2019

Rhode Islanders are setting brushfires for freedom once again as they advance a Second...

See More Trending Articles

More How-To

When facing a crises, there are only two types of people—the prepared and the unprepared. The How-To

How to Create the Ultimate Grab-and-Go Survival Bag

Brad Fitzpatrick - July 01, 2015

When facing a crises, there are only two types of people—the prepared and the unprepared....

Give me a Garand, a pocket full of clips and a place to shoot it, and I'm a happy man. The M1 is How-To

Troubleshooting The M1 Rifle: Bolt Release Timing

Gus Norcross - February 09, 2015

Give me a Garand, a pocket full of clips and a place to shoot it, and I'm a happy man. The M1...

Hodgdon has launched three new how-to videos on its popular Reloading Data Center, which is not How-To

Hodgdon Reloading Data Center Videos

SGN Online Editors - June 08, 2014

Hodgdon has launched three new how-to videos on its popular Reloading Data Center, which is...



Without a doubt, it was a bit awkward and the side-mounted magazine didn't help its balance any. How-To

Shooting the MP-28 Submachine Gun

David Fortier - June 09, 2016

Without a doubt, it was a bit awkward and the side-mounted magazine didn't help its balance...

See More How-To

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.