300 Blackout Upper

300 Blackout Upper

Every 300 Blackout upper available here has been properly configured to handle both subsonic and supersonic cartridges, suppressed or un-suppressed, with utter reliability. We stuck with 1:8 and 1:7 twist rates to ensure a proper balance of stability between both cartridges, without the risk of keyholing subsonics or over-stabilizing supersonic loads. Each 300 blackout upper assembly is hand-assembled by an experienced builder and shooter to ensure proper configurations and torque are applied before shipment.

Learn more about 300 Blackout's ballistics and find comparisons to 5.56 NATO here.

300 BLK Upper Features

  • Not a firearm, no FFL required
  • 100% mil-spec construction
  • Fully assembled barreled upper receivers
  • 5.56/.223, 300 Blackout options available
  • Proudly made and assembled in the USA

Additional Upper Specifications

  • All barrels are forged from MIL-B-11595 E steel (4150 or Chromoly Vanadium)
  • All stainless barrels forged from Crucible 416R steel, offering sub-MOA accuracy
  • All barreled threaded with standard 1/2x28 threads with A2-type flash hider
  • All BCGs are M16 in profile with chrome lining and properly staked gas keys
  • All stripped upper receivers forged from mil-spec 7075 T6 aluminum
  • All barrels are test-fired to ensure proper accuracy and reliability
  • All receivers come with mil-spec Type III anodized coating

Made in the USA, Lifetime Warranty

With so many AR-15 uppers on the market, it's tough finding one that's affordable, but not cheap. We only use the highest-quality 4150 Chromoly or 416R stainless steel when we build each barrel. With the right skill, you can hit sub-MOA accuracy with our uppers. Each of our uppers ships complete and ready-to-fire out of the box. Every upper is also backed by a Lifetime Warranty.

No FFL required for shipment

No parts in any of our 300 Blackout upper kits are considered a firearm by the ATF, so they ship directly to your front door! Even if you pick up an 80% lower with your upper, the ATF considers them receiver blanks -- not firearms. That means you can legally build your AR at home with no FFL requirements, no paperwork, and no federal bureaucracy.

State Laws May Vary

Contrary to federal law, some states have either restricted or banned the sale, transfer, and ownership of 80% lowers, firearm blanks, and other gun parts. Because of these restrictions, we cannot ship our products to certain states. Please confirm whether your state is restricted on our Shipping & Return Policy before placing an order. We cannot fulfill orders to restricted states if placed.

Your 300 BLK build awaits.


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

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We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.