Diamondback 6.5 Grendel 18 Inch AR 15 Barrel – Midlength Gas – Nitride

SKU: 6.5M18M50B8

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AT3™ Low Profile Steel Gas Block + Gas Tube + Roll Pin Combo

AT3™ Low Profile Steel Gas Block + Gas Tube Combo - .750" Gas Block, Midlength Tube


AT3™ AR-15 Bolt Carrier Group -  6.5 Grendel Type II - Black Nitride

AT3™ AR-15 Bolt Carrier Group - 6.5 Grendel Type II - Black Nitride


High-Value 6.5 Grendel Barrel for Hunting AR-15s

Diamondback makes great barrels at excellent prices, and this barrel for 6.5 Grendel is no exception.  Constructed from 4150 CMV steel for durability over a lifetime of rounds fired, with a nitride finish to resist corrosion, this barrel is built to last.  The 18 inch length also keeps your 6.5mm bullets at high velocity, enabling you to reach out to long distance for each shot.  Plus, the midlength gas system gives the barrel plenty of dwell time for reliability, and keeps recoil mild.

Note: This barrel is 6.5 Grendel Type 2.  Be sure to use a compatible 6.5 Grendel Type 2 BCG.


  • Caliber: 6.5 Grendel
  • Finish: Nitride
  • Gas System: Mid-Length
  • Length: 18″
  • Weight: 27 oz.
  • Profile: Medium
  • Material: 4150 CMV Steel
  • Twist Rate: 1:8
  • Muzzle Thread: 5/8 x 24
  • Rifling: Button Rifled 6-Groove Bore
  • 11° Target Crown


Caliber6.5 Grendel Type II
Barrel Length18 inches
Barrel Twist Rate1:8 inches
Barrel Material4150 CMV
Muzzle Threads5/8/2024
Barrel FinishBlack Nitride
Gas Block Size.750″ Gas Block
Barrel ProfileMedium
Barrel Gas SystemMidlength
Gas Block Journal Length1.9 inches
Barrel ExtensionM4
Weight27 ounces

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.

Limited Lifetime Warranty

  • This “Limited Lifetime Warranty” has been drafted to comply with the MAGNUSON-MOSS WARRANTY FEDERAL TRADE COMMISSION IMPROVEMENT ACT which is effective for goods manufactured on or after December 31, 1976. DIAMONDBACK FIREARMS, LLC. warrants that this firearm was originally manufactured free from defects in material and workmanship.
  • DIAMONDBACK FIREARMS, LLC. agrees to correct any defect in material and/or workmanship for the original purchaser by repair or replacement ONLY. PROOF OF PURCHASE IS REQUIRED. A service or handling charge may be applied at the company’s discretion.
  • DIAMONDBACK FIREARMS, LLC. will not be responsible for defects resulting from careless handling, unauthorized adjustments or modifications, corrosion, neglect, abuse, failure to provide reasonable and necessary maintenance as described by this owners manual.
  • Damage caused by hand loaded and/or reloaded or improper ammunition or damage caused by firing with any obstruction in the barrel will not be warranted.
  • This warranty does not apply to ordinary wear and tear of any parts, including metal, plastic, or any other material used to manufacture this product, as well as all surface finishes.
  • Diamondback does not warranty aftermarket parts or damage or issues caused by them.
  • Under no circumstances shall DIAMONDBACK FIREARMS, LLC. be responsible for incidental or consequential damages with respect to economic loss or injury or property damage, whether as a result of a breach of an express or implied warranty, negligence or otherwise.
  • Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply in certain cases.

Illegal Configuration

Diamondback reserves the right to report illegal configurations to the ATF for guidance. Please ensure all NFA parts or modifications have the proper paperwork associated with them prior to shipment. This includes short barrel rifle configurations.

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.