Upper Build Kit 7.5" 5.56 Pistol - Black | A2 | 7.25" M-LOK | With BCG & CH

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Product Code: UBK-RTB75S55675RA2
Quantity in Stock Quantity in Stock: IN STOCK
MSRP: $514.95
Sale Price: Sale Price: $267.95
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Upper Build Kit 7.5" 5.56 Pistol - Black | A2 | 7.25" M-LOK | With BCG & CH

This build kit DOES NOT come assembled. 

This Complete 7.5 inch M-LOK upper receiver build kit comes with a 7.25 inch free float handguard and includes only the best Mil-Spec components for your AR15 build. The core components of this kit are a barrel that’s machined from chrome moly vanadium 4150 steel, the lightweight M-LOK handguard that is machined from 6000 aeries aluminum, an M4 upper that is machined from 7075 T6 forgings, and our black nitride bolt carrier group that is finished with an incredible polish, making the action smooth and easy to keep clean.

As a “do it yourselfers" or DIY enthusiast, you may prefer an AR-15 build kit over a complete upper. Building an AR-15 from a kit allows for a greater level of customization and personalization of the final product. DIYers can choose from a variety of components, such as barrels, handguards, and triggers, to create a rifle that meets their specific needs and preferences. Additionally, building an AR-15 from a kit can be a rewarding and educational experience, as it allows you to gain a deeper understanding of how their firearm functions and how to properly maintain it. Building an AR-15 from a kit may often be more cost-effective than purchasing a complete upper, as it allows DIYers to select only the components they need, rather than paying for pre-assembled parts they may not want or need.

We also carry this Upper Receiver Kit assembled here.

Caliber 5.56
Length 7.5
Material 4150 Chrome Moly Vanadium
Profile Medium
Finish QPQ Corrosion Resistant
Gas System Length Pistol
Gas Block Journal .750"
Dimpled? No
Twist Rate 1:7
Muzzle Thread 1/2x28 TPI
Weight 16.8oz
Barrel Extension M4 Feed Ramps
Target Crown 11 Degree


Bolt Carrier Group:

  • Enhanced 9310 Steel (Bolt)
  • 8620 Tool Steel (Carrier)
  • Bolt is shot Peened and MPI
  • All BCG components pre polished before being processed and then post polished for an incredible shine

Upper Receiver:

  • Machined from a Mil-Spec 7075 T6 Forging
  • Hard Coat Anodized per Mil-A-8625F, Type III
  • M4 Feed ramps


  • 7.25" Lightweight - Free Float M-LOK

Charging Handle:

  • Forged 7075 Aluminum construction
  • Mil-Spec Type-III Hardcoat Anodized finish