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AT3™ FF-ML 16 Inch .300 BLK Complete Upper – .300 AAC Blackout 16 Inch Ballistic Advantage Barrel – 15″ M-LOK Free Float Handguard
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.
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 16″ .300 BLK Rifle Upper with 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 M4 Nitride Barrel (with low profile gas block & pistol gas tube)
Ballistic Advantage Modern Series barrels feature precision-machined 4150 CMV steel, durable QPQ (Nitride) coating, and a Sub-MOA accuracy guarantee.
Unique slim and lightweight design with M-LOK attachment points. Rock-solid 6061 aircraft aluminum handguard that withstands the harshest treatment. 5-slot M-LOK-to-Picatinny rail section included
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.
KAK Industry Flash Can
One of the most popular muzzle devices for AR15 pistols. The conical shape directs muzzle blast and noise directly in front of the shooter, reducing concussion for the shooter. The flash can is only 1.2″ in diameter, and can hold up to recoil without the need for a crush washer or timing.
Optional Upgrades (use the dropdown menu to select):
(Only $94 – save $6 vs regular price)
AT3 Tactical partnered with the best BCG manufacturer in the industry – Toolcraft Inc – to produce these Top-Tier Bolt Carrier Groups. They feature M16-style carriers, MPI/HPT inspected bolts, 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.
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: 26″
- Gas System: Pistol
- Barrel Profile: DRP (Distinct Rigid Pattern)
- Twist Rate: 1:7
- Barrel Steel: 4150 Chrome Moly Vanadium
- Barrel Finish: QPQ Corrosion Resistant (Nitride)
- Chamber: .300 AAC Blackout
- Muzzle Thread: 5/8×24
- Barrel Extension: M4
- Diameter at Gas Block: .750″
- 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 ReviewsWrite a review
This is one of the best uppers I have ever bought, right out of the box you can tell the quality of this upper.
I ordered the AT3 FF-ML 16 Inch .300 BLK Complete Upper (.300 AAC Blackout 16 Inch Ballistic Advantage Barrel - 15" M-LOK Free Float Handguard) in FDE. The upper was shipped quickly, was very well packaged, the price was excellent, and the finish is perfect. But, above all, I was most impressed with the customer service (specifically, Alvin)... He went above and beyond in terms of keeping me apprised of my order status every step of the way (from the point they received my order to the product arriving in my hands). I'll definitely be an AT3 customer for life. Thank you!