FN Barrel AR-15 5.56x45mm Government Contour 1 in 7" Twist Hammer Forged Chrome Lined Chrome Moly Matte

The FN Barrel AR-15 5.56x45mm in government contour is a hammer-forged AR barrel built on over a century of FN's precision barrel manufacturing. This is the same cold hammer-forging process and Chrome Moly Vanadium steel that FN uses in its machine gun barrels—proven to withstand sustained fully-automatic fire. Whether you're building a duty rifle, a precision carbine, or a general-purpose AR, you get a barrel engineered for accuracy, durability, and reliability right out of the box.

Every FN hammer-forged barrel undergoes Magnetic Particle testing to catch micro-stresses and material flaws before shipping, ensuring consistency across the production run. The 1:7 twist rate handles a wide range of 5.56 ammunition, from lighter varmint loads to heavier combat rounds. Chrome lining throughout the bore and chamber resists corrosion and heat erosion, which directly translates to longer barrel life and dependable feeding and extraction cycle after cycle. The government contour profile balances weight and stiffness—lighter than a pencil barrel, stiffer than a profile designed purely for economy builds.

The matte finish is a Manganese Phosphate coating that stands up to handling, cleaning solvents, and environmental exposure without the upkeep of raw steel. M4-style feed ramps and barrel extension ensure reliable chambering no matter your upper receiver or feeding system. Gas block journal is machined to .750", the standard for modern AR mid-length and carbine systems. This is a no-nonsense replacement or new-build barrel from a manufacturer known for making barrels that work.

Key Features

• Cold hammer-forged from Chrome Moly Vanadium steel—the same material in FN military-contract barrels
• Magnetic Particle tested for material integrity and freedom from micro-stresses
• Chrome-lined bore and chamber for corrosion resistance and extended barrel life
• 1:7 twist rate accommodates a wide range of 5.56x45mm ammunition
• M4-style feed ramps for reliable feeding and chambering
• Manganese Phosphate matte finish resists external corrosion and oxidation
• Government contour profile—proven balance of weight and rigidity
• .750" gas block journal fits standard AR systems

Specifications

Frequently Asked Questions

What lengths and gas system options are available for this barrel?

FN produces this hammer-forged 5.56 barrel in 14.5" carbine, 16" carbine, 16" mid-length, and 18" and 20" rifle-length gas system configurations. Verify the specific length and system for the model you're ordering.

Will this barrel work with my AR-15 upper receiver and bolt carrier group?

Yes. The barrel uses a standard M4-style extension and .750" gas block journal, compatible with any mil-spec or commercial AR-15 upper receiver and bolt carrier group. M4 feed ramps ensure smooth feeding across receiver types.

Is chrome lining necessary, and does it affect accuracy?

Chrome lining improves barrel life by resisting corrosion and heat erosion, especially valuable if you shoot frequently or in harsh environments. The lining is thin and does not measurably degrade accuracy in modern AR barrels—FN's hammer-forging process ensures bore concentricity.

What ammunition does the 1:7 twist rate stabilize?

A 1:7 twist is fast enough to stabilize heavier 5.56 rounds (up to 77 grains and beyond) and also shoots lighter ammunition reliably. This makes it a versatile choice for duty, hunting, and general range use across a broad spectrum of 5.56 loads.