16″ .400 Legend AR-15 Barrel – 4150 CMV Nitride, Carbine Gas
Build a reliable and accurate .400 Legend AR-15 hunting rifle with this 16-inch .400 Legend barrel from Mid State Firearms. Designed for hunters and builders looking for a powerful straight-wall cartridge option in the AR-15 platform, this barrel delivers excellent performance, durability, and dependable cycling with quality factory ammunition.
Manufactured from 4150 CMV steel and finished with a durable nitride treatment, this barrel provides excellent wear resistance, corrosion protection, and long service life. The 16-inch length offers an ideal balance of velocity, maneuverability, and handling, making it an excellent choice for deer hunting, hog hunting, and general-purpose big-bore AR builds.
Precision Features for Reliable Performance
Each barrel is designed with features that improve installation, reliability, and overall function:
- .400 Legend chamber
- 16-inch barrel length
- 1/16/ twist
- 4150 CMV steel construction
- Nitride finished for durability and corrosion resistance
- Carbine length gas system
- 5/8×24 muzzle threads for common .30 caliber suppressors and muzzle devices
- Dimpled 180 degrees opposite the gas port for consistent gas block alignment
- Enhanced feed ramp geometry for improved cartridge feeding
- AR-15 compatible barrel extension
The precision dimple located opposite the gas port provides a reliable indexing point for proper gas block installation, helping ensure correct alignment during assembly and reducing installation guesswork.
Designed for the .400 Legend AR-15 Platform
The .400 Legend was designed to give hunters increased performance over traditional straight-wall AR cartridges while maintaining the familiar ergonomics and customization of the AR-15 platform. This barrel is an excellent foundation for a dedicated hunting upper capable of delivering increased bullet diameter and energy while maintaining manageable recoil.
For proper function, .400 Legend builds require a compatible 6.8 SPC pattern bolt and appropriate magazines.
Mid State Firearms Quality
At Mid State Firearms, we focus on producing and sourcing dependable AR components built for real-world use. Every barrel is inspected before shipping to ensure it meets our standards for fit, finish, and performance.
Whether you are building a new hunting rifle or upgrading an existing AR platform, this 16″ .400 Legend barrel provides the performance and reliability needed for your next build.
Technical Specifications
Caliber: .400 Legend
Barrel Length: 16″
Material: 4150 CMV Steel
Finish: Nitride
Gas System: Carbine Length
Muzzle Thread: 5/8×24
Gas Block Journal: .750″ (assuming standard .750 — confirm)
Feed Ramp: Enhanced
Gas Port Alignment: Dimpled 180° opposite gas port
Platform: AR-15
Bolt Required: 6.8 SPC pattern
sound of freedom – This was a great set up. I loved being able to customize the set up. Only issue I had was my own fault as a newb to building these. I used a heavy barrel in a slim hand guard. It makes adding attachments tough with clearances. Hoping someday to also get an AR10 from here.