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AT3™ Complete Rifle Kit – Magpul Lower Build Kit – .223/5.56 16 Inch Ballistic Advantage Barrel – M-LOK Free Float Handguard


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Lifetime WarrantyOn All AT3 Brand Products

All AT3 Tactical Brand Products carry a lifetime warranty against manufacturer’s defects.

This includes AT3 Red Dot Sights, Handguards, Iron Sights, and any other product that carries the “AT3 Tactical” or “AT3™” name. For other brands (ex. Magpul or Troy), please refer to the manufacturer’s warranty policy.

In the event that your AT3™ product becomes unusable, we will repair or replace the product at no charge to you.

If we cannot repair your product, we will replace it with a product in perfect working order of equal or better physical condition. The warranty is fully transferable, but we may require information about the original purchase to validate the authenticity of the product.

If your product is in need of warranty service, please contact AT3 Tactical to start the process

Our contact info is available here. To expedite processing, please provide your order information and description of the defect.

Please note: The AT3 Lifetime Warranty does not cover loss, theft, intentional damage or cosmetic damage that doesn’t affect the performance of the product.

Fast & Free Shipping On orders over $50

You will receive fast, free shipping for all orders over $50

Shipping cost is $7.99 for orders under $50. We ship with UPS or USPS, depending on the item.

Most orders received by 1pm CST ship the same day

You will receive an email with tracking information at the time of shipment. To expedite shipping, we may ship your order from multiple warehouses. Orders placed on weekends, holidays, or after 1pm will ship the following business day.

Instant Rifle.  Just Add Lower.

Don’t settle for the budget-line rifle kits you’re used to seeing.  Get a complete assembled upper from AT3 Tactical, with a lower build kit including a Magpul CTR Stock and Pistol Grip, plus our enhanced Nickel Teflon Trigger assembly.  This is absolutely the best bang for your buck.

The AT3 Rifle Kit Includes:

  • AT3 FFML 16″ M-LOK Complete Upper

    • Lightweight Ballistic Advantage Barrel
    • AT3 SPEAR M-LOK Handguard and Billet Upper
    • AT3 Black Nitride Bolt Carrier Group
    • Your Choice of Muzzle Device and Charging Handle
  • AT3 Enhanced Nickel Teflon Trigger Group
  • Magpul CTR Stock, MOE Pistol Grip, and Trigger Guard
  • AT3 Buffer Tube Kit and Lower Parts Kit

Freedom of Choice

Your choice of standard Black, Magpul Flat Dark Earth, Magpul Stealth Grey, and Magpul OD Green to have your receiver, handguard, and all furniture matching on your new build!


Your choice of 3 different muzzle devices (choose type with dropdown menu)

Complete Upper Muzzle Devices - A2 Flash Hider, Combat Flash Hider

Learn more about these muzzle devices: A2 Flash HiderCombat Flash Hider


Your choice of Standard GI or Extended-Latch Charging Handle

Quality 7075-T6 charging handles – choose between standard latch and extended latch designs.

More info:

This product is built-to-order in our Minnesota facility. Quality takes time – please allow up to 7 days for your order to ship.

All AT3 upper assemblies come with a Lifetime Warranty – if you ever have an issue, let us know, and we’ll make it right. It’s that simple.

Don’t see the options you’re looking for? Let us quote you a custom rifle kit – contact us now.


  • Barrel Length: 16″
  • Gas System: Midlength
  • Barrel Profile: Pencil
  • Twist Rate: 1:7
  • Barrel Steel: 4150 Chrome Moly Vanadium
  • Barrel Finish: QPQ Corrosion Resistant (Nitride)
  • Chamber: 5.56 NATO
  • Muzzle Thread: 1/2-28
  • Barrel Extension: M4
  • Diameter at Gas Block: .625″
  • Gas Block Type: Low-profile
  • Receiver Material: Billet 6061 T6 Aluminum
  • Receiver Extension Material: 6061 T6 Aluminum

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Customer Reviews

Based on 4 reviews
Great buy

This is a great deal on a great build kit. Once you get the lower this kit is ready to rock n roll. No issues at all.

Thanks for sharing your feedback, Jase. We're glad you're satisfied with your purchase. Cheers!

When I first stumbled upon AT3 I was in the market for a 223 kit that was not only affordable but a true value and I found it ! This kit is the best bang for your buck , most kits try to sell you a substandard barrel with mediocre parts BUT not AT3, the Ballistic Advantage Barrel is the heart of this kit and if you ask any AR enthusiasts they will all tell you it comes down to the quality of said barrel. The upper assembly is as tight , no gaps , this looks like a high end rifle through and through! And how many kits offer cerakote colors without an upcharge, no one but AT3 , This is my new favorite of my 223s and if your worried about no forward assist ,DONT, you'll never need it with this beauty , the action is so smooth ! My next kit will be the same but in OD Green , don't miss out you will regret not getting one especially if one of your buddies does , THANK YOU AT3 FOR EXCEPTIONAL SERVICE AND A QUALITY WEAPON , YOUR MY NEW GO TO STORE !!!

Thanks for sharing your feedback, Peter. We're glad you're satisfied with your purchase. Cheers!
Solid deal. Great shipping & communication. Everything is perfect.

Got the complete kit + a couple upgrades. Packaging was great. My favorite is the FDE coating on the hand guard & upper receiver...smooth and looks great. Zero complaints from me. Solid value at that price. Paired mine with the green laser LEOS and an Aero Precision FDE lower. I'M HAPPY!

Thanks for sharing your feedback, Johnny. We're glad you're satisfied with your purchase. Cheers!
Milling was great

The only thing I didn’t like was it came with a Magpul milspec stock and a commercial buffer tube, I think if your selling a complete kit u should be able to build it without having to change the parts it comes with

Thanks for sharing your feedback, Dillan. We'll make sure to send compatible parts moving forward. If you need help with anything, please don't hesitate to reach out to us.