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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AT3™ Red Tail™ Rifle Scope with Mount - 1-6x Magnification


AT3™ Red Tail™ Rifle Scope with Locking Caps – 1-4x or 1-6x Magnification – 5.56 Illuminated BDC Reticle

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

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

AT3 Lifetime Warranty Logo

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

This includes AT3 Red Dot SightsHandguardsIron 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.

Customer Reviews

Based on 7 reviews
Great build

Great beginner build kit it's complete with everything you need except the lower. I enjoyed the process start to finish, learned some things along the way. Brought it to the range Sunday. Minimal adjustments need spot on every shot

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


This is my first AR but I have shot a lot of them. I have seen a bunch of my friends build them and they all love this AT3. Many of them after shooting it say they wish they had found a deal like this when they were looking. The finish is awesome the lines are slick. The way the rail meets the upper is beautiful and a very nice touch. I built this upper on a spikes tactical lower and it fits phenomenally. Nice and tight. No wiggle. I chose the grey option. It's quiet enough to not say look at me but when people see it up close they love it. The grey adds a nice classy touch. Everything operates smoothly and I have not had a single operational issue with it after about 1800 rounds shooting all kinds of diffrent ammo. Price plus quality... I highly recommend anyone looking to build to check AT3 out first. Can't wait to build a 300 blackout using you product AT3. Thanks again for the quality and top notch customer service.

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

Jayson Powell
Excellent quality

This complete kit is excellent! The fit and finish was perfect, not a single complaint. The trigger feels great, everything assembled super smooth. Definitely will be buying from AT3 again!

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

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!

Peter Figueroa

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!