MPN: WH-UR-16-556


  • Caliber: 5.56 NATO
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver: Mil-Spec AR-15 Upper - 7075-T6 Aluminum
  • Handguard: Battle Arms Development 15-Inch WORKHORSE Free-Float M-LOK Rail
  • M4 Feed Ramps: Yes
  • Muzzle Device: A2 Flash Hider
  • Barrel: 16" 1:7 Nitride Coated 4150 Chrome Moly Vanadium Barrel
  • Muzzle Thread Pattern: 1/2"-28 TPI
  • Gas Block: .750" Low-Profile Gas Block
  • Gas Tube: Mid-Length Gas tube
  • Bolt Carrier Group: Not Included
  • Charging Handle: Not Included

*This upper assembly does not come with Bolt Carrier Group and Charging Handle


  • Weight: ~3.24 lbs.
  • Length: ~24.5"


  • AR-15 lower receiver


  • 1x Battle Arms Development 16-Inch 5.56 WORKHORSE Upper With M-LOK Rail


If you’re doing an AR-15 build and need an upper that is reliable, modern, and well made, you should check out the Battle Arms Development 16-Inch 5.56 WORKHORSE Upper With M-LOK Rail. This upper assembly has all the features for a high-quality AR-15 that looks amazing and shoots great as well.

The Battle Arms WORKHOUSE Upper Has A High-Quality Barrel

This upper assembly comes with a high-quality Nitride coated Chrome Moly Vanadium Barrel. Chrome, molybdenum, and vanadium are impurities added to the 4150 steel of the barrel to make it stronger, wear-resistant, and corrosion resistant, allowing your barrel to last longer than a simple one chrome-lined barrel. The barrel is also Nitride coated for corrosion resistance and longevity.

The barrel has many similarities with a standard Military M4 barrel. It is 16 inches long, has an A2 profile flash hider, and has a fast, 1:7 twist rifle sling, which makes the barrel more accurate with heavier rounds.

Smooth Shooting Gas System

The Battle Arms WORKHOUSE Upper has a mid-length low profile gas system. The mid-length gas tube allows the rifles to operate more smoothly and reliably. It puts enough pressure on the bolt carrier group to make the rifle cycle reliably without over-pressuring the chamber and increasing recoil and wear.

The low profile gas block also allows for a full-length free-floating M-LOK handguard which offers a better sight picture, more landscape to mount accessories, and get a longer grip to control the rifle and shoot more stably and accurately.

Lightweight and Sturdy Upper Receiver

The upper receiver of the WorkHouse Upper is made from 7075-T6 Aluminum, which is very durable and lightweight. The receiver and M-LOK rail also have a Hardcoat Anodized finish, which improves its longevity and makes it look great.

The receiver is chambered for 5.56 or .223 Remington rounds and features M4 feed ramps, which ensure more reliable feeding for various kinds of ammunition.

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  • This Item: Battle Arms Development 16-Inch 5.56 WORKHORSE Upper With M-LOK Rail
    MSRP: $529.99
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