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AT3™ FF-ML Complete Rifle Upper - .223/5.56 16" Ballistic Advantage Barrel - M-LOK Free Float Handguard

AT3™ FF-ML Complete Rifle Upper – .223/5.56 16″ 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.

Uncompromising quality meets unbeatable value. The AT3 Tactical FF-ML Complete AR-15 Upper, now with the SPEAR M-LOK Handguard!

AT3 Complete Upper assemblies are Built for Accuracy and Reliability – Guaranteed.

  • Quality Where it Counts – premium components like Ballistic Advantage barrels, and AT3 Tactical’s handguards and uppers. Don’t settle for “bargain uppers” with unknown components.
  • Guaranteed Reliability– Carefully assembled before shipment, and backed by the AT3 Lifetime Warranty
  • Unbeatable Value – Unbeatable quality in the price range. Save up to 20% off vs purchasing the components separately.

This fully assembled AR-15 complete upper includes:

16″ Ballistic Advantage 1:7 4150 CMV Midlength Pencil Barrel (with low profile gas block & midlength gas tube)

Ballistic Advantage Modern Series barrels feature precision-machined 4150 CMV steel, durable QPQ (Nitride) coating, and a Sub-MOA accuracy guarantee. The lightweight profile offers better handling than front-heavy “Government” profile barrels, and the Midlength gas system produces less felt recoil.

AT3 SPEAR Free Float M-LOK handguard

AT3 Tactical Spear M-LOK Handguard 15 Inch

Lightweight and tough, this unique M-LOK handguard is the best rail we offer. This rock-solid 6061 aircraft aluminum handguard that withstands the harshest treatment. 5-slot M-LOK-to-Picatinny rail section included

AT3 Tactical Slick Side 6061 T-6 Upper Receiver

Precision machined from 6061-T6 aluminum, this assembled upper is sleek, with extra material around the barrel extension for superior accuracy. It mates perfectly with our SPEAR handguard and feature M4 feedramps for reliable feeding of ammunition.

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

Optional Upgrades (use the dropdown menu to select):

AT3 Black Nitride Bolt Carrier Group

AT3 Tactical provides Top-Tier Bolt Carrier Groups with all the uppers we sell. They feature M16-style carriers, MPI inspected bolts made from 9310 steel, and properly staked grade 8 gas key screws.

Your choice of Standard GI or Extended-Latch Charging Handle

(Discounted Pricing – Save $4 vs regular price)

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 upper – contact us now.


  • Barrel Length: 16″
  • Total Assembly Length: 24.5″
  • Gas System: Midlength
  • Barrel Profile: Pencil profile
  • 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

3 reasons why AT3 Complete Uppers are better than the rest.

1 – Quality Where it Counts

The single most important component of an accurate AR-15 is the barrel. AT3 uppers are built using Ballistic Advantage barrels with a Sub-MOA Accuracy Guarantee.

But the quality doesn’t stop at the barrel. Our AT3 handguard and upper work together to provide superior accuracy, meaning this upper assembly offers quality without compromises.

Many of the “bargain” complete uppers on the market source their parts from the lowest bidder – at the expense of accuracy and reliable function. AT3 is committed to using only top-quality components in our upper assemblies.

2 – Guaranteed Reliability

AT3 complete uppers are assembled with strict quality controls and carefully packaged for delivery to the customer. All AT3 complete uppers offer a Lifetime Warranty – if you ever have an issue, let us know, and we’ll make it right. It’s that simple.

3 – Unbeatable Value

When you buy a complete upper, you’ll save money and parts and assembly vs purchasing the components separately. Our complete uppers are not the cheapest on the market, but they deliver unbeatable quality in the price range. We sell direct to the customer, and cut out the middle-men, to deliver the best value in AR-15 upper assemblies.

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Customer Reviews

Based on 4 reviews
First order

I purchased a complete upper for my first build. Although I have not completed my build yet, I carefully inspected the upper, m-lock handguard and barrel. The fit, finish, and feel are excellent. Shipped right away too. Awesome sales price as well. Will definitely be ordering from AT3 Tactical again.

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

Bought an upper for my first (lower) build. These guys were more than helpful and took great care of me.

The simple fact that I’m taking the time to write a review should say it all.

Thanks for sharing your feedback, Al. We're glad you're satisfied with your purchase. Cheers!
Real quality upper

Nicest upper I have handled

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

I got this complete upper during the Labor Day sale. I also had them switching the gas block with an Odin that I had which I sent them. I made another change and added a Lantec Dragon. The customer service was amazing, and communication was spot on. They even discounted the Lantec Dragon against the gas block and A2 flash hider that came off the upper. Shipping was unbelievable! 2 day shipping was included, I had the upper faster than I could get tracking number. The upper for the price is everything I could ask for and much much more! Thanks AT3 Tactical.

We are glad to hear that you are pleased with your complete upper and the customer service you received.