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Rainier Arms Mountain MOD2 5.56 NATO Barrel


In stock

Satisfaction Guarantee

We are so confident in our barrels that we offer a 100% money back guarantee within 90 days of purchase.  If our barrels don’t meet or exceed your expectations, for any reason, return it for a full refund.

As low as $300.00
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Allow us to reintroduce ourselves. We have brought back our Mountain Series of barrels for those of you who want the accuracy you expect from Rainier Arms in a nearly indestructible package. These barrels are made out of 4150 CMV and nitrided as well. That means these barrels will take anything you can throw at them. They are meant to be shot, and shot a lot. The half-fluted profile maximizes heat dissipation and helps reduce weight.



  • 4150 CMV Steel
  • Twist: 1:7
  • Thread Pitch: 1/2x28
  • .750 Gas Block Seat
  • 5.56 NATO Chamber
  • M4 Feed Ramps
  • Half-Fluted Profile


Length/Gas System/Weight:

  • 10.5" / Carbine / 1 lb 4.48 oz
  • 12.5" / Mid / 1 lb 8.64 oz
  • 14.5" / Mid / 1 lb 12.8 oz
  • 16" / Mid / 1 lb 15.3 oz


Our Craftsmanship Guarantee

We are so confident in the craftsmanship of our barrels, if our barrel doesn’t outshoot your similar priced barrel, send it back for a full refund. While most companies strive for faster production time to cut cost, we strive only for quality. Our barrels are made the old-fashioned way by True Barrel Artisans™. Every barrel is carefully chambered & crowned by hand. We have a few secrets up our sleeves that no CNC machine can reproduce. There are no shortcuts with our barrels, period.

We will go toe to toe with anyone and win.

More Information
Product Type Barrel
Manufacturer Rainier Arms, LLC
Gas Block Diameter .750"
Thread Pitch 1/2x28
Twist Rate 1:7
Color Nitride
Barrel Profile Half-Fluted
Caliber 5.56 NATO

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