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.300 Blackout AR 15 Pistol Kit - 7.5" Parkerized Heavy Barrel, 1:8 Twist Rate with 6.5" MLOK Handguard

Out of Stock

Build a suppressor-ready, subsonic-optimized 300 BLK tack driver.

Building an accurate, reliable 300 Blackout-chambered AR-15 can be a challenging: Your setup must be able to reliably cycle supersonic and subsonic loads, suppressed and un-suppressed, to truly perform. We've configured this AR pistol build kit to do exactly that. With a 7.5" heavy barrel, 1:8 twist rate, and dialed in gas system and buffer assembly, this is the kit you need to build a 300 BLK AR ready eat up and spit out suppressed subsonic loads.

What’s Included

This is not a firearm. It includes an assembled upper receiver, bolt carrier group, charging handle, lower parts kit, and buffer system.

300 BLK Pistol Upper Assembly Specs

Barreled uppers are assembled in-house before shipment.


  • Chamber: .300 AAC Blackout
  • Contour: Heavy
  • Length: 7.5"
  • Twist Rate: 1:8
  • Gas System: Pistol
  • Gas Block: 0.750"
  • Muzzle Threads: 5/8x24
  • Feed Ramps: .30 Cal
  • Material: 4150 CMV
  • Finish: Parkerized
  • Process: Button Rifled
  • Lining: None
  • Extension: M4
  • Muzzle: Fluted Flash Hider


  • Attachment System: 6.5" M-LOK
  • Finish: Type III Hardcoat Anodized (Mil-Spec)
  • Top Rail: M1913 Picatinny
  • Material: Billet 6061-T6 Aluminum
  • Attachment: Barrel Nut 

Upper Receiver

  • Profile: M4 Flattop
  • Material: Billet 6061-T6 Aluminum
  • Finish: Type III Hardcoat Anodized (Mil-Spec)

Bolt Carrier Group

  • Profile: M16/Full-Auto
  • Steel: AISI E9310
  • Exterior: Black Nitride
  • Interior: Black Nitride
  • Gas Key: Staked
  • Charging Handle: Included, Right Side Charging

Lower Receiver Parts

  • Buffer System: AR-15
  • Pistol Brace: SBA3 5-Position
  • Parts Kit: Mil-Spec LPK

Lower receiver assembly sold separately. 

WARNING: Handling firearms parts and accessories can expose you to lead and other petroleum products known to the State of California to cause cancer and reproductive harm. For more information go to:

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

.300 AAC Blackout
Barrel Size:
Barrel Finish:
Twist Rate:

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, Hawaii, 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.