FAXON INTEGRAL® SERIES 16" PENCIL BRAKE PROFILE MID-LENGTH 5.56 NATO AR15 BARREL

Rifle Barrels › Integral Muzzle Device Barrels › 16″ Pencil 5.56 NATO  |  Works with: .625″ gas block • mid gas tube • 5.56/300 BLK BCG • 13″ handguard

What Integral Means

Most 16″-overall barrels with a short feel are a 14.5″ barrel with a muzzle device pinned and welded on to reach legal length. That works, but it is permanent: the device can’t come off, and on many builds the barrel nut and handguard are trapped behind it. Faxon’s Integral® Series machines the muzzle device from the same piece of 4150 CMV as the barrel. There is no separate device to time, shim, pin, or weld, and the device is perfectly concentric with the bore because it was cut on the same setup.

The slim 3-port brake vents gas up and to the sides to tame muzzle rise and recoil. It can’t be removed or swapped, and there are no muzzle threads, so this is not a suppressor host. If you want the same barrel with the other device, see the Integral A2 flash hider version.

The 16″ Pencil Profile and Mid-Length Gas

The Pencil profile is Faxon’s lightest contour. It heats up quickly but also cools quickly, and because every Duty Series barrel is stress relieved and 100% wet magnetic particle inspected, it is a surprisingly rugged barrel that punches above its weight. It is not a benchrest profile, and it is not meant to be. Mid-length gas moves the port farther from the chamber than carbine gas, for a softer, smoother impulse and less wear on the bolt.

The 5.56 NATO chamber runs both 5.56 NATO and .223 Remington ammunition, and the 1:8 twist stabilizes the common 55 to 77 gr bullets.

Built on the Duty Series

Integral® Series barrels are built on Faxon’s Duty Series architecture: 4150 CMV steel, button rifled, stress relieved, 100% wet magnetic particle inspected, and salt-bath QPQ nitrided inside and out. Nitride is a diffusion treatment, not a plating. It hardens the bore and exterior while adding virtually nothing to them, a few ten-thousandths of an inch, roughly a tenth the width of a human hair, and it needs little to no break-in. Faxon AR-15 and AR-10 barrels have been voted Favorite Aftermarket Barrel by Shooting Sports Retailer every year since 2022, the Gold Award.

How it compares to Faxon’s other lines: Match Series is 416-R stainless with 5R rifling and the same nitride finish; MATCH-X takes 416-R further with a honed and lapped bore; and the Combat Series offers classic configurations with a manganese phosphate exterior and chrome-lined bore. Chrome lining still has its place, mainly sustained full-auto fire, but for most shooters nitride does what they need and more.

What’s in the Box

How It’s Made

1. Drill and ream: The 4150 CMV bar is gun-drilled and reamed.
2. Button rifle: Button rifled, 1:8 twist.
3. Air gauge: Bore air gauged.
4. Stress relieve: Stress relieved at the blank stage, then qualified true to the bore.
5. Profile and device: Pencil profile turned and the integral 3-port brake machined from the same blank, on the same axis as the bore.
6. Chamber: 5.56 NATO chamber cut.
7. MPI and nitride: 100% wet magnetic particle inspected, then salt-bath QPQ nitrided inside and out.
8. Port and extension: Gas port drilled; M4 extension torqued, pinned, and headspaced.

How We Inspect It

Faxon barrels are built to a written control plan, and each run is logged on inspection sheets. Here is what this barrel goes through before it ships.

What Owners Say

Average rating: 5.0 out of 5 stars from 2 reviews on FaxonFirearms.com. The standard 16″ Pencil barrel this one is built on has its own reviews too.

Build It Out: Faxon Parts That Fit This Barrel

Compare Your Options

See every barrel in this line on the Integral Muzzle Device Barrels page.

Integral® 16″ Pencil FAQs

Is this barrel legal for a rifle build?

Yes. The integral 3-port brake is machined into the barrel, so the barrel measures 16″ overall with no pin and weld. That meets the federal 16″ minimum for a rifle barrel; know and follow your state and local laws too.

Can I remove or change the muzzle device?

No. The device is part of the barrel blank, and there are no muzzle threads. Choose the other Integral version if you want a different device.

Will it work with a suppressor?

No. The barrel isn’t threaded and the integral device can’t be removed, so it isn’t a suppressor host. If you plan to shoot suppressed, choose a threaded Duty Series barrel.

Why not just pin and weld a 14.5?

A pinned and welded device is permanent and often traps the barrel nut and handguard behind it. With an Integral barrel there is nothing to pin or weld, the device is concentric with the bore, and the barrel nut, gas block, and handguard can still come off.

What gas block and gas tube does it take?

A .625″ low-profile gas block on the 1.1″ journal and a mid-length gas tube. Faxon’s fixed and adjustable .625″ blocks both fit.

Is a Pencil profile durable?

Yes. It heats up quickly and cools quickly, and because the barrel is stress relieved and 100% wet magnetic particle inspected, it is surprisingly rugged and punches above its weight. It is not a benchrest profile and isn’t meant to be.

What does 4150 CMV and nitride mean?

4150 CMV is a chrome-moly-vanadium barrel steel known for toughness and wear resistance. Salt-bath QPQ nitride is a diffusion treatment, not a plating, so it hardens the bore and exterior while adding virtually nothing to them, and it needs little to no break-in.

Is it full-auto capable, and how much heat can it take?

Yes. Like every Faxon nitrided rifle barrel, it is full-auto capable. The barrel is stress relieved, magnetic particle inspected for flaws, and salt-bath nitrided at roughly 1,050°F, so the steel and the nitride are stable far beyond normal firing temperatures. What limits any barrel on automatic fire is heat. A good guideline, drawn from U.S. military guidance for the M4 carbine: about 12 to 15 rounds a minute can be fired indefinitely, and continuous rapid fire should stop at about 150 rounds so the barrel can cool. Light profiles like the Pencil heat up faster than heavier contours. Push past that and throat wear speeds up, which shortens barrel life. If the barrel smokes or starts to glow, stop: near 1,000°F the steel is approaching the temperature it was nitrided at, where it can begin to soften and the nitride can lose hardness, and military testing has seen M4 barrels fail at about 1,360°F. A hot chamber can cook off a round in as little as 10 seconds, so clear it quickly or keep it pointed in a safe direction. And heat affects accuracy in every barrel: groups open up as it heats. Faxon’s stress relieving and machining keep point of impact from walking, but let it cool before you check zero or shoot for groups.

Where is it made, and what is the warranty?

Made in Greater Cincinnati, Ohio, and covered by the Faxon Lifetime Guarantee.

Full-auto heat guidance is general, based on published U.S. military rate-of-fire guidance and steel and nitride data, not Faxon testing; barrel life under automatic fire depends on rate of fire, ammunition, and cooling. Glock® is a registered trademark of Glock, Inc.; Faxon is not affiliated with Glock. HARMONIX® and MuzzLok® are trademarks of Faxon Firearms. Know and follow all federal, state, and local laws.