AR-15 .400 Legend 16" Rifle Kit, 1:16 Twist, Quad Rail, LE Stock

.400 Legend Rifle Kit: Specs & What's Included

Built for shooters looking for a .400 Legend AR-15 rifle configuration, this Moriarti 16" .400 Legend AR-15 rifle kit combines a 4150 CrMoV barrel, forged slick-side upper receiver, free-float quad rail, M16-style bolt carrier group, Mil-Spec lower parts kit, and adjustable LE-style stock system.

The 16" .400 Legend barrel features a 1:16 twist, carbine-length gas system, .750" gas block journal, 5/8x24 muzzle threads, and durable black nitride finish.

This kit includes the components listed below for completing a compatible AR-15 configuration. Lower receiver is not included.

Color options are available at the top of the page. Applicable components are Cerakoted in your selected color.

16" .400 Legend Barrel

At the heart of this rifle kit is a 16" .400 Legend medium-profile barrel manufactured from 4150 CrMoV steel and finished in black nitride for increased surface durability and corrosion resistance.

Barrel Specifications:

• Caliber / Chamber: .400 Legend
• Barrel Length: 16"
• Profile: Medium
• Material: 4150 CrMoV
• Finish: Black Nitride
• Twist Rate: 1:16
• Gas System: Carbine Length
• Gas Block Journal: .750"
• Muzzle Thread: 5/8x24 (.40 Cal)
• Muzzle Device: A2-Style Flash Hider

Free-Float Quad Rail

The barrel is paired with an aluminum free-float quad-rail handguard, providing four-sided accessory-mounting space while keeping the handguard isolated from direct barrel contact.

The handguard is Cerakoted in your selected color where applicable, allowing you to personalize the appearance of your .400 Legend rifle configuration.

Forged Slick-Side Upper Receiver

The kit features a precision-machined 7075-T6 forged M4 flat-top upper receiver with a clean slick-side configuration.

• 7075-T6 forged aluminum
• M4 flat-top design
• Slick-side configuration
• No forward assist
• Ejection port cover
• Optics-ready top rail
• Selected components Cerakoted according to chosen color

M16-Style Bolt Carrier Group

A complete M16-cut bolt carrier group is included for the listed .400 Legend configuration - 6.5 Grendel cal.

• M16-cut carrier
• Chrome-lined carrier
• 9310 steel bolt
• MPI tested
• Complete bolt assembly
• Cam pin
• Firing pin
• Firing pin retaining pin

AR-15 Charging Handle

An AR-15 tactical charging handle is included and Cerakoted to coordinate with the selected color configuration where applicable.

Mil-Spec AR-15 Lower Parts Kit

Includes a DPMS-style Mil-Spec AR-15 lower parts kit containing the listed components for use with a compatible stripped AR-15 lower receiver.

Lower receiver is not included.

M4 LE Adjustable Stock & Buffer System

The rifle kit includes an M4 LE-style 6-position adjustable stock and Mil-Spec buffer system.

Included:

• M4 LE-style adjustable stock
• 6-position Mil-Spec buffer tube
• AR-15 buffer
• Buffer spring
• Required buffer-system components

Kit Highlights

.400 Legend | 16" Barrel | 1:16 Twist | Medium Profile | Carbine-Length Gas | .750" Gas Block Journal | 5/8x24 Threads | Black Nitride | Forged Slick-Side Upper | Free-Float Quad Rail | M16-Style BCG | Mil-Spec Lower Parts Kit | M4 LE Adjustable Stock | Color Options Available

Important Product Information

This .400 Legend AR-15 rifle kit comes unassembled and includes the components shown and listed for the selected configuration.

Lower receiver is not included.

Product images are representative and may not be an exact representation of the final product. Appearance and individual components may vary according to selected configuration, color, and component availability.

Why is a 16-inch barrel popular for a .400 Legend AR-15?

A 16-inch barrel is a popular choice for .400 Legend rifles because it provides a practical balance of rifle-length performance and maneuverability while keeping the configuration relatively compact. For hunters, a 16" AR-15 can also be easier to carry and handle than a longer rifle. This Moriarti configuration pairs its 16" .400 Legend barrel with a 1:16 twist, medium profile, carbine-length gas system, and 5/8x24 muzzle threads. Actual ballistic performance depends on the ammunition used.

FAQ

Is a lower receiver included?

No. The lower receiver is sold separately; you finish the build on your own AR-15 lower.

What bolt and magazines does it use?

Magazines made for .400 Legend are recommended for reliable feeding.

Related: .400 Legend parts kits · all AR-15 parts kits

Images may not be an exact representation of the product.