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Rainier Arms Ultramatch MOD2 300 Blackout 14.5" 1-7.5 Twist .800 Gas Block TiN Ext 5/8-24 Thread Satin Finish

Out of stock

Rainier Arms Ultramatch MOD2 300 Blackout 14.5" 1-7.5 Twist .800 Gas Block TiN Ext 5/8-24 Thread Satin Finish

From $379.95

To $439.94

Standard Gas Block & Gas tube Included

RA Adjustable Gas Block Upgrade for $59.99

Introducing our MOD2 UltraMatch barrel using the finest blank. Our goal is to mass produce them to bring them to market at the most competitive prices. We wanted the best balance between accuracy while keeping the weight down as much as possible. We are so confident in our UltraMatch barrels that we will offer a 100% money back guarantee within 90 days of purchase. If you aren't completely satisfied with the barrel for any reason, return it for a full refund, no questions asked.


  • Stainless Steel Match Grade Blank
  • TiN Extension
  • Length: 14.5"
  • Twist: 1:7.5
  • Thread Pitch: 5/8 X 24
  • .800 Gas Block Seat
  • 300 AAC Rainier Match Chamber
  • Pistol Gas System
  • M4 Feed Ramps
  • Proprietary Contour
  • Weight: 1 lb 13.9 oz

Rainier Arms Low Profile Gas Block:

  • 416 SS
  • Finish: Melonite
  • Ultra Low Profile.
  • Weight 1.7 oz
  • Made in the USA

Adjustable Gas Block:

Bleed Off”, direct impingement, gas block for the AR15 platform adjusts the gas flow by bleeding the gas out of the block instead of restricting the flow like conventional adjustable blocks.  Results:

  • The pressure used in the block is reduced only to the amount required to drive the bolt carrier. The remaining gas / pressure are bled out of the block allowing the system to run much cleaner and cooler. 
  • Reduction of felt recoil.
  • Patent pending adjustment detent is located outside of the block and therefore no contamination.
  • The gas adjustment screw does not restrict the gas flow; therefore there is no erosion or seizing of the screw / no loss of detent due to carbon build up.  Although it is removable, we have added a safety mechanism, which stops you from unintentionally backing the screw all the way out.
  • When using SBR’s and / or suppressors the bleed off port allows the excessive pressure to be exhausted out of the block reducing blow back. 


  • Gas Block Material: 416 SS
  • Finish: Melonite or Matt Stainless
  • Barrel Diameter:0.625" -0.875"-0.750" - 0.936"
  • Weight:  1.80 oz
  • Length: 1.00"
  • Attachment Type: Solid
  • Gas Adjustment:  (Patent Pending) 30 Locked Positions, Front Of Block 
  • Bleed Off Port:  (Patent Pending) Front Of Block


  • Gas Block - Assembled
  • (2) 10-32 x 3/16" Socket Head Cap Screws
  • (1) Gas Tube Roll Pins
  • (1) 3/32 X 6" L-Shaped Hex Keys

Our Craftmanship Guarantee

We are so confident in the craftmanship 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
SKU RAB-UM2-300-P14.5-SAT-B
Manufacturer Rainier Arms Barrels
Material 416r SS
Thread Pattern 5/8 x 24
Grade Ultramatch Mod 2
Twist Rate 1:7.5
Gas Block Diameter .800"
Gas Length Pistol
Finish Satin
Profile Medium Contour
Barrel Length 14.5"
Caliber 300AAC