300 Blackout AR 15 Rifle Kit (16" Nitride Barrel & 15" Keymod Handguard) w/ 80% Lower



Want an AR upper that’s super lightweight, while retaining the most rail space possible? Looking for the most accurate, well-built AR capable of shooting subsonic suppressed and supersonic with one gas system and barrel? If that sounds expensive, you’re wrong. You’ve found the perfect AR Build Kit: Our .300 AAC blackout rifle upper comes with 16″ barrel and 15″ lightweight keymod handguard. This upper provides the most rail length with the least weight possible, and its profile, capability, and reliability make this AR upper assembly a standard go-to rifle for any level of operator.

Made in The USA

Sure, a lot of rifle parts are built in the States, but our 300 blackout AR-15 upper assembly is head and shoulders above the rest. Each assembly we build features a barrel constructed from 4150 Chromoly Vanadium (mil-spec) steel, M4 feed ramps, a flat-top M4 upper receiver, keymod and picatinny rail attachments, type III hard coat anodized finish, and the expectation of providing 1-MOA accuracy at 100 yards with ease.


Gas System: Carbine-length
Barrel Profile: Heavy, Fluted
Barrel Steel: 4150 CMV (mil-spec)
Barrel Finish: Parkerized
Chrome Lining: No
Muzzle Thread: 5/8×24
Chamber: .300 AAC Blackout
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: 15” keymod
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” Carbine-Length Black-Barreled AR 15 Rifle Kit:

  • 100% legal to own and ship to your front door
  • Not considered a firearm – no FFL paperwork needed!
  • Chrome moly vanadium steel barrel and Freedom parts kit ensure sub-MOA accuracy
  • Prebuilt upper with gas system removes the guesswork of rifle making
  • Includes bolt carrier group, free-floated M-Lok handguard and lower parts kit

AR 15 Rifle Kit Details (Expanded):

Barrel: Heavy, fluted, 16″, carbine-length with Parkerized finish, chambered in .300 BLK, 1:8 twist rate, .750″ low-profile gas block, 15” keymod handguard, with an A2 “birdcage” flash hider.

Upper Receiver Assembly: Forged from 7075 T6 aluminum, hard-coat anodized in black for durability, features M4 feed ramps, and are made in the USA.

Bolt Carrier Group: The bolt carrier is made from 9310 steel and has a staked gas key and black nitride finish. The bolt itself comes complete with an extractor spring and O-ring insert.  It accepts .223 Remington, 5.56mm, and .300 BLK calibers (though you should NEVER attempt to use a caliber for which your rifle is not chambered), and is magnetic particle inspected.

80% Lower Receiver: Choose to receive a forged or billet Fire/Safe 80% lower receiver.  Our lower receivers are anodized to match the upper receiver perfectly. and they come ready for machining of the trigger pocket and drilling of the safety selector and trigger pin holes.

AR-15 Lower Parts Kit: includes all parts needed to complete the lower receiver including pistol grip, mil-spec safety selector, and trigger/fire control group.

Lower Assembly: comes with complete buffer tube assembly including buffer, buffer spring, six-position buffer tube, latch plate, castle nut, and butt stock based on original Colt design.

Charging Handle: standard size, made from 6061 aluminum.

Please note: This build kit requires that the builder complete the 80% lower receiver themselves, but that’s the rewarding part of the experience (and the only way to build your own AR-15 without the need of an FFL transfer or serialization).

No FFL required  Made in the USA  Lifetime Warranty

Shipping Restrictions

Shipping of various parts and/or accessories are prohibited to states and locales (ie New Jersey, California, New York, etc…) with restrictions against certain parts and/or accessories or “assault weapons” (i.e. states with high-capacity magazine restrictions, manufacturing of semi-automatic weapons, etc..). It is your responsibility to be aware of your local firearms laws before purchasing from our website or machining a firearm. We try our best to keep our shipping page current, but laws change daily

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