AT3™ 300 Blackout Medium Profile 6 Inch AR-15 Barrel

SKU: AT3-300-6

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MI AR .30 Caliber Blast Diverter - .308/.300 Blackout

Midwest Industries AR .30 Caliber Blast Diverter - .308/.300 Blackout


6 Inch .300 Blackout Barrel by AT3 Tactical

This 6-inch .300 Blackout Barrel makes a great choice for your short, heavy-hitting pistol or SBR AR-15 builds. Made from 4150 CMV steel per Mil-B-11595E, and finished with a durable black nitride treatment, this barrel holds up under pressure, with excellent corrosion resistance. This barrel fits all your standard AR-15 uppers if you’re going for a fresh build, with M4 feed ramps for reliability.

This barrel uses a .750″ diameter gas block, plus a Pistol length gas tube, both of which you can snag here at a lower, bundled cost.

All NFA/ATF Rules Apply
You may use this barrel with a lower receiver that is a Registered SBR, Machine Gun, or Pistol. Possession of this barrel along with a Non-NFA lower receiver is Prohibited, except when installed on a Pistol configuration firearm.


  • Length: 6 Inches
  • Material: 4150 Chrome Moly Vanadium
  • Profile: Medium
  • Finish: Black Nitride
  • Gas System Length: Pistol
  • Gas Block Journal: .750″
  • Twist Rate: 1:7 inches
  • Muzzle: 5/8×24 Threaded
  • Barrel Extension: M4 Feed ramps

Where are these barrels made?

AT3 has partnered with Kinetic Manufacturing, a trusted OEM manufacturer for the firearm industry to produce these barrels. We have a philosophy that great parts for the AR don’t have to break the bank, and these barrels are no exception. Our lifetime warranty on these barrels applies to any defects due to workmanship. In the unlikely event you run into an issue, we will take care of you.

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

AT3 Lifetime Warranty Logo

All AT3 Tactical Brand Products carry a lifetime warranty against manufacturer’s defects.

This includes AT3 Red Dot SightsHandguardsIron 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.