Colt M4Cqb Replacement Barrel Assembly 10.3In

The Colt M4CQB Replacement Barrel Assembly 10.3In is a genuine OEM barrel component sourced directly from Colt's production line—the same barrels that ship on factory rifles. Built for AR-15 pistol builds, short-barreled rifle (SBR) projects, or complete upper assemblies, this 10.3-inch barrel assembly arrives ready to install with all the key components you need to get downrange. If you're upgrading an existing rifle or starting a new build from the ground up, a quality barrel is the foundation of accuracy and reliability, and Colt's M4CQB delivers the fit and finish you expect from the manufacturer.

This barrel assembly features chrome-lined construction that resists fouling and corrosion—critical for a short, high-velocity barrel that cycles hard and heats up fast. The rifling is six-groove with a 1:7-inch twist rate, a proven profile optimized for .223 Remington and 5.56 NATO across a wide range of bullet weights. M4-style feed ramps ensure smooth feeding regardless of your magazine choice. The gas system is carbine-length, standard for most AR platforms and widely supported by accessories and gas tube components. At the muzzle you'll find 1/2"-28 TPI threading, opening up options for sound suppressors, flash hiders, or muzzle devices.

Colt's M4CQB barrels carry the credibility of a manufacturer that has been engineering and producing AR barrels for decades. This assembly configuration includes the barrel nut, front-sight tower with post, and sling swivel attachment point—everything needed to attach an upper receiver and gas tube. Whether you're building a home-defense carbine, a recce rifle, or a practical duty-rifle platform, starting with a Colt OEM barrel means starting with proven design and quality control.

Key Features

• Genuine Colt OEM barrel assembly—production-line quality
• Chrome-lined bore resists corrosion and extends barrel life
• 10.3-inch length optimized for AR pistols and short-barreled rifles
• 1:7-inch twist rate handles 55gr to 77gr ammunition
• M4-style feed ramps for reliable feeding
• Carbine-length gas system—widely compatible
• 1/2"-28 TPI muzzle threading for suppressors and muzzle devices
• Includes barrel nut, front-sight tower, post, and sling swivel

Specifications

Frequently Asked Questions

What's included in this barrel assembly?

The assembly comes complete with the barrel, barrel nut, front-sight tower, post, and sling swivel attachment. You'll need to source a gas tube, bolt carrier group, and upper receiver to complete the build or replacement.

Can I use this barrel for an AR pistol or SBR build?

Yes. The 10.3-inch length and carbine-gas system are well-suited to both AR pistol builds and short-barreled rifle (SBR) platforms. Verify your local and federal regulations regarding barrel length and tax stamp requirements if building an SBR.

What ammunition does the 1:7 twist rate stabilize?

The 1:7-inch twist rate is optimized for standard .223 Remington and 5.56 NATO ammunition across typical bullet weights, including 55-grain, 62-grain, and heavier projectiles out to 77 grains.

Is this barrel compatible with standard AR-15 uppers and accessories?

Yes. The barrel features carbine-length gas tube compatibility, standard M4-style feed ramps, and 1/2"-28 TPI muzzle threading—all common AR-15 specifications. Confirm compatibility with your specific upper receiver before assembly.