Description
A full-length 20-inch barrel is still the best way to squeeze every bit of velocity out of a 5.56 round, and this Faxon Duty Series barrel does it without turning your rifle into a nose-heavy club. The secret is the Gunner profile, which keeps government-style thickness from the extension back to the gas block where rigidity and heat resistance matter, then tapers down to a pencil-thin front end past the gas block. The result is a barrel that shifts the balance point back toward you for better handling on longer strings, offhand shots, and all-day range or field time.
What the Gunner Profile Brings to a 20" Build
Running a rifle-length gas system, this barrel gives you the smoothest, softest recoil impulse the AR platform offers, which is exactly what you want when you're chasing tight groups or shooting suppressed. It's chambered in 5.56 NATO so it happily eats .223 Rem too, and the 1:8 twist is the sweet spot for stabilizing everything from 55-grain plinking loads up through 77-grain match ammo. The 1/2-28 muzzle threads accept your favorite brake, comp, or suppressor adapter, and the .625" gas block journal runs 1.9" long, with an adjustable block being a smart move if you plan on running a can.
Faxon Duty Series Build Quality
Faxon machines these barrels in-house in Cincinnati from certified 4150 CMV steel, then treats them inside and out with a QPQ black nitride finish for serious corrosion resistance and easy cleanup. Every Duty Series barrel is stress relieved, air-gauge tested, magnetic particle inspected, and headspace verified before it ships, and each one wears an 11-degree target crown for consistent bullet release and repeatable accuracy. It uses a standard M4 barrel extension, so it drops into any mil-spec AR-15 upper and works with a standard bolt.
Who This Barrel Suits
If you're piecing together a practical DMR, an SPR-style precision rifle, or a lightweight hunting AR that still reaches out there, the 20" Gunner hits a rare balance of long-barrel velocity and nimble handling. It's a lot of barrel for the money and a proven choice for accuracy-focused builds.
Key Specifications
- Manufacturer: Faxon Firearms
- Model: Duty Series Gunner
- Manufacturer Part Number: 15A58R20NGQ
- UPC: 816341020214
- Caliber: .223 Rem / 5.56x45mm NATO
- Barrel Length: 20"
- Twist Rate: 1:8
- Profile: Gunner Light Hybrid
- Gas System: Rifle-Length
- Barrel Material: 4150 CMV Steel
- Finish: QPQ Black Nitride (inside and out)
- Muzzle Thread: 1/2-28 TPI
- Gas Block Journal: .625" diameter, 1.9" length
- Gas Port Diameter: .093"
- Barrel Extension: M4
- Crown: 11-degree Target Crown
What’s Included
- Faxon Duty Series 20" Gunner Profile 5.56 NATO barrel
Frequently Asked Questions
Does the Faxon Duty Series 20" barrel come with a gas block or gas tube?
No, this listing is for the bare barrel only. You'll need to add a .625" gas block sized for the 1.9" journal along with a rifle-length gas tube to complete your setup. An adjustable gas block is worth considering if you plan to run a suppressor.
What ammo works best with the 1:8 twist on this Gunner barrel?
The 1:8 twist is a versatile all-arounder that stabilizes the full range of common 5.56 and .223 loads. It handles everything from 55-grain range ammo up through 69 and 77-grain match projectiles, which makes it a great choice for a rifle that pulls double duty between plinking and precision work.
Is this Faxon Duty Series barrel suppressor friendly?
Yes. The rifle-length gas system already delivers a soft, smooth impulse that pairs well with a can. Pairing it with an adjustable gas block lets you dial back the extra back-pressure that comes with suppressed shooting for even better manners.
Will the 20" Gunner barrel fit a standard AR-15 upper?
It will. The barrel uses a standard M4 barrel extension, so it drops into any mil-spec AR-15 upper receiver and runs with a standard bolt. Just match it with a rifle-length gas tube and an appropriate buffer for reliable cycling.







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