.300 AAC Blackout Rifle Upper Assembly - (16" Parkerized Barrel & 13.5" M-Lok Handguard)



If you're looking for a fast and easy way to convert your .223 or 5.56mm-rifing AR-15 into a .300 AAC Blackout rifle, look no further.  This upper assembly comes to you complete and ready to go out of the box.  Just pull the pivot and takedown pins from your current upper assembly, swap it out for the new one, and push the pins back through.  It's really that easy. With this completely prebuilt upper assembly, you get a 16" parkerized barrel with a 13.5" inch M-Lok free-floating handguard for mounting accessories like foregrips, tac lights, or whatever else.  All you need to do is add either backup sights or optics of your choice.  Your old .223 / 5.56mm mags will even work with the new .300BLK rounds.


Gas System: Pistol-length

Barrel Profile: M4

Barrel Steel: 416R

Barrel Finish: Parkerization

Chrome Lining: No

Muzzle Thread: 5/8×24

Chamber: .300BLK

Twist Rate: 1:8

Barrel Extension: M4

Gas Block Size: .750″

Gas Block Type: Low-profile

Muzzle Device: A2 Flash hider

Receiver Material: Forged 7075 T6

Receiver Type: M4

Handguard Type: 13.5″ lightweight M-Lok free float

Bolt Carrier Group Included: Yes

Bolt Steel: 9310 steel, magnetic particle inspected

Bolt Carrier Profile: Full-auto

Charging Handle Included: Yes

Overall Length: 24.5″

Benefits of the 16” Pistol-Length Parkerized AR 15 Upper Assembly:

  • 100% legal to own and ship to your front door
  • Not considered a firearm – no FFL paperwork needed!
  • 4140 steel barrel and Freedom parts kit ensure sub-MOA accuracy
  • Prebuilt upper with gas system removes the guesswork of rifle making
No FFL required  Made in the USA  Lifetime Warranty

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80-Lower.com only ships within the United States. Federal legislation dictates we cannot ship our products internationally.

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.