Faxon Firearms Duty Series 15A4L16C16Ngq Gunner 400L 16

The Faxon Firearms Duty Series Gunner 400L is a 16-inch replacement barrel built for shooters who demand a durable, no-nonsense upgrade. Chambered in 400 Legend, this modern intermediate cartridge delivers rifle-class ballistics in a compact, maneuverable package—ideal for hunting medium game, tactical training, or any scenario where velocity and ergonomics matter. Whether you're building an AR or upgrading an existing platform, a quality aftermarket barrel transforms accuracy and extends the working life of your firearm.

Faxon barrels are known in the community for precision machining and attention to detail. The 16-inch length offers a natural balance between sight radius, handling, and muzzle velocity—short enough for tight spaces, long enough to extract the potential from 400 Legend's case. Nitride finish is the go-to hardening process for professional and competition shooters: it resists corrosion, handles heat cycling, and requires minimal maintenance compared to traditional bluing.

The 4150 CMV steel alloy used in this barrel is a proven, mil-spec standard. CMV stands for Chrome-Molybdenum-Vanadium, a formulation that balances toughness and fatigue resistance across thousands of rounds. You're getting a barrel that can handle both sustained fire and the demands of a working rifle.

If you're rebarreling an AR or assembling a new build in 400 Legend, this Faxon barrel pairs with standard AR-15 gas systems and dimensioning. Installation requires basic armorer tools and knowledge; many shooters have a gunsmith handle the fit and headspacing. It's a smart foundation for a rifle that needs to run hard and stay accurate.

Key Features

• 16-inch length balances handling and velocity for 400 Legend cartridge
• 4150 CMV steel construction meets mil-spec durability standards
• Nitride finish provides superior corrosion resistance and heat tolerance
• Precision-machined for tight tolerances and consistent accuracy
• Compatible with standard AR-15 gas systems

Specifications

Frequently Asked Questions

Will this barrel fit my AR-15 platform?

Yes, this barrel is machined to standard AR-15 dimensions and works with common AR gas systems. However, installation requires proper headspacing and should be done by someone with armorer experience or a gunsmith.

What is 400 Legend and why choose it?

400 Legend is a modern intermediate cartridge that delivers rifle ballistics in a short, handy rifle. It's gaining adoption among hunters and shooters who want a stepping stone between pistol calibers and full-power rifle rounds, with less recoil than many traditional hunting loads.

Why is nitride finish preferred for barrels?

Nitride hardening creates a surface finish that resists corrosion better than bluing, withstands heat cycling from sustained fire, and requires less ongoing maintenance. It's the standard finish on professional and military barrels.

Do I need a gunsmith to install this barrel?

While skilled reloaders and gunsmiths can install barrels with proper tools and headspacing knowledge, we recommend a qualified gunsmith to ensure proper fit, timing, and safety.