The Faxon Duty Series 12.5" Gunner Profile 5.56 NATO barrel blends two proven contours — Government and Pencil — to deliver strength where it matters and weight savings where it counts. Built in-house from certified 4150 CMV and finished black nitride inside and out, this mid-length gas barrel provides smooth timing, excellent balance, and repeatable accuracy in a compact package.

Key Benefits

• Balanced Gunner contour: Government strength behind the gas block with Pencil-style weight savings forward for quick handling and reduced fatigue.
• Mid-length gas reliability: 12.5" with mid-length gas offers smoother cycling and easier tuning (suppressed or unsuppressed) than shorter systems.
• Duty-grade materials: Certified 4150 CMV, button-rifled 1:8 twist, and black nitride finish for longevity and corrosion resistance.
• Accuracy-focused: Fully stress relieved, air-gauge tested, MPI, and finished with an 11° target crown.
• Build-friendly interface: Standard 1/2-28 muzzle threads and .625" gas block journal (1.9" length) for broad compatibility.
• In-house QC: Individually headspace-checked with precision gauges before it leaves our Cincinnati facility.

Specifications

Why Choose the Gunner Profile

The Gunner profile brings the rifle’s balance back toward the shooter, enhancing control and reducing fatigue through long training days or hunts. Government contouring behind the gas block preserves rigidity where forces are highest, while the Pencil-like forward section trims weight without sacrificing a full shoulder for secure muzzle device and suppressor mounting.

Installation & Compatibility

• Standard M4 barrel extension fits AR-15 uppers and bolts.
• Use a .625" gas block on the 1.9" journal; low-profile adjustable blocks pair well for suppressed builds.
• 1/2-28 muzzle threads support common brakes, comps, and direct-thread suppressor adapters (verify suppressor caliber rating).
• Tune buffer/spring and gas for your ammo and muzzle device to optimize reliability and recoil impulse.

Frequently Asked Questions

Overview: The 12.5" Mid-Length 5.56 Barrel Sweet Spot

For many builders, 12.5 inches with a mid-length gas system is the modern sweet spot for a compact 5.56 carbine. The Faxon Duty Series Gunner Profile 12.5" 5.56 NATO barrel is engineered to make the most of that configuration, offering smoother gas timing than shorter systems and a noticeable improvement in balance over heavier profiles. By blending Government rigidity behind the gas block with a Pencil-like forward section, the Gunner profile keeps the rifle lively, reduces front-end weight, and helps bring the center of gravity back toward the shooter for faster transitions and less fatigue.

Faxon starts with certified 4150 CMV bar stock and employs button rifling with a versatile 1:8 twist to stabilize common 55–77 grain 5.56 projectiles. Each barrel is fully stress relieved to minimize point-of-impact shift over time and is treated with a durable black nitride finish inside and out to enhance wear and corrosion resistance. Attention to detail matters: an 11° target crown promotes consistent gas release at the muzzle, and every unit is air-gauge tested, magnetic particle inspected, and individually headspace-checked with precision gauges before leaving our Greater Cincinnati, Ohio facility.

The interface is builder-friendly: a .625" gas block diameter with a 1.9" journal supports common low-profile blocks, while standard 1/2-28 muzzle threads accept a broad range of brakes, comps, and direct-thread suppressor adapters. Pair the barrel with an appropriate buffer and spring, and consider an adjustable gas block for fine-tuning — especially when running a suppressor — to dial in reliability and recoil.

Whether you’re assembling a compact defensive rifle, a suppressor-ready carbine, or a do-everything training setup, the Faxon 12.5" Gunner profile delivers the right mix of light weight, durability, and accuracy that modern shooters demand. It’s a confident, duty-grade foundation for your next AR-15 build.