Technical Information

Upper Receiver: A3 Flat-Top

Barrel Length: 16"

Barrel Contour: Medium

Barrel Material: 4140 Chrome Moly Steel

Muzzle Thread Pattern: 5/8"-24

Chrome Lined: No

Barrel Finish: Salt Bath Nitride

Twist Rate: 1 in 7"

Weight: 4.25 lbs

Chamber: 300 AAC Blackout

M4 Feed Ramps: Yes

Muzzle Device: A2 Flash Hider

Gas System Length: Carbine

Gas Block Diameter: 0.750"

Handguard: Polymer M4-Style

Sights: None, Receiver Height Single Rail Gas Block

Bolt Carrier Assembly Included: Yes

Bolt Carrier Type: Mil-Spec

Suitable for use with Subsonic or Supersonic loads, either Suppressed or Unsuppressed

Compatible with all standard AR-15 magazines (including Pmags), No Magazine Included

This CMMG AR-15 M4 LE Upper Assembly is chambered for the exciting new 300 AAC Blackout cartridge and is ready for instant, drop-in use on any standard small pin lower receiver. Perfect for a myriad of different uses from hunting, to personal defense, to competition or just plain fun, the 300 AAC Blackout offers shooters 30 caliber firepower in a standard AR-sized envelope. The M4 LE features a Forged 7075-T6 Aluminum A3 Flat-Top Receiver that is ideal for adding an optic and/or rear iron sight, and comes equipped with a 16" Medium Contour Barrel with a 1 in 7" twist for easy stabilization of heavy match projectiles. The upper comes complete with a receiver height single rail gas block, A2 flash hider, bolt carrier group, charging handle and M4-style polymer handguards. Magazine not included.The Chrome Moly Steel Barrel is finished inside and out with a Salt Bath Nitride finish. The SBN process surface-hardens the metal, extending barrel service life by reducing friction in the bore and lessening bore surface wear. Also referred to as Salt Bath Nitriding, this treatment produces an extremely hard, slick surface on steel that resists carbon adhesion and increases corrosion resistance, making for easier cleaning and maintenance. Nitriding converts the steel's surface without any build-up, retaining all of the benefits of traditional chrome lining without suffering the accuracy degradation commonly encountered due to uneven application of chrome inside the barrel's bore.This 16" 300 AAC Blackout Upper utilizes the versatile Carbine Length Gas System, a good choice for this cartridge if various weights and types of ammunition are to be used. Most Subsonic and Supersonic loads, fired from either a Suppressed or Unsuppressed gun, are compatible with this configuration. However, some subsonic ammunition may not always cycle reliably under adverse conditions or in a severely fouled firearm without a sound suppressor attached to provide extra backpressure.All CMMG uppers are test fired at their facility before shipment to the end user.

Please Note: Installation of AR-15 upper assemblies with certain features including, but not limited to: flash hiders, bayonet lugs, and threaded muzzles may violate state and/or local laws.