CMMG 55DE10A 16.1" Nitrided Barrel Assembly for 223 Remington/5.56 NATO

The CMMG 55DE10A 16.1" nitrided barrel assembly for 223 Remington/5.56 NATO is a complete, ready-to-assemble upper component for AR-15 builders who want a proven platform without the hassle of sourcing and headspacing individual parts. This barrel assembly arrives pre-installed with an M4 barrel extension and has been factory headspaced to ensure reliable feeding and extraction right out of the box—saving you the time and precision equipment typically required for proper AR upper assembly.

Built with a salt bath nitride finish, this barrel resists corrosion and wear during both range sessions and field use, making it a practical choice for shooters who want durability without premium pricing. The 16.1" length and carbine-profile gas system strike a balance between velocity and handling in a compact form factor well-suited to home defense, competition, or general-purpose shooting. The 1-in-7 twist rate stabilizes a broad spectrum of 223/5.56 ammunition, from lighter varmint loads to heavier tactical rounds.

If you're building an AR upper and want the confidence of factory headspacing without custom fitting, this pre-assembled barrel saves critical steps. Pair it with a compatible upper receiver, bolt carrier group, and charging handle to complete your build. CMMG's focus on AR compatibility and straightforward specifications means you know exactly what you're getting—no surprises.

Key Features

• Pre-installed M4 barrel extension—no additional fitment required
• Factory headspaced for reliable feeding and extraction
• Salt bath nitride finish for corrosion resistance and durability
• 16.1" barrel with carbine-profile gas system for balanced handling and velocity
• 1-in-7 twist rate accommodates light to heavy 223 Remington/5.56 NATO ammunition
• ½-28 thread pitch for standard AR muzzle devices

Specifications

Frequently Asked Questions

Is this barrel assembly pre-headspaced?

Yes. The CMMG 55DE10A comes from the factory properly headspaced with the M4 barrel extension already installed, so you can confidently assemble it into an upper receiver without custom fitting or precision equipment.

What AR-15 uppers will this fit?

This is a barrel assembly designed for standard AR-15 upper receivers. You'll need a compatible upper receiver, bolt carrier group, and charging handle to complete your build. The ½-28 muzzle threads accept standard AR muzzle devices.

What ammunition does the 1-in-7 twist rate work with?

The 1-in-7 twist is a versatile all-purpose rate that stabilizes a wide range of 223 Remington and 5.56 NATO ammunition, including lighter varmint rounds and heavier tactical or match-grade loads.

What's the difference between this 16.1" barrel and a longer option?

The 16.1" length with carbine-profile gas system offers a compact, maneuverable setup suitable for home defense, intermediate-distance shooting, and general-purpose use. Longer barrels typically provide slightly higher velocity and sight radius, while shorter profiles are faster to handle and easier to maneuver in tight spaces.