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Rainier Arms 5.56 NATO 4150 Chrome Moly Barrel 1:7 Twist Rifle Length- 18" SPR

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Rainier Arms 5.56 NATO 4150 Chrome Moly Barrel 1:7 Twist Rifle Length- 18" SPR


Inspired by the Army's DM-R rifle, this Stainless Steel barrel features 12 large flutes to reduce weight and aid in cooling. With nearly a full pound of weight removed from the first 12 inches of the barrel, where coincidentally, the majority of heat is generated, the surface area is increased by a whopping 81%. The barrel is produced with match grade blanks in 1:7 twist yielding light weight and excellent accuracy needed for many applications.

We wanted to build an AR15 barrel using the finest blank and 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. 


  • Chrome Moly Match Blank
  • Twist: 1:7
  • Thread Pitch: 1/2 X 28
  • .750 Gas Block Seat
  • 5.56 NATO Chamber
  • M4 Feed Ramps
  • Special Purpose Rifle SPr Contour
  • Nitride Finish
  • 18" - Rifle Gas System
  • Weight 2lb 8 oz

 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
Manufacturer Rainier Arms Barrels
Material 4150 CM
Thread Pattern 1/2 x 28
Grade Mountain Mod 2
Twist Rate 1:7
Gas Block Diameter .750"
Gas Length Rifle
Finish Black Nitride
Profile SPR
Barrel Length 18"
Caliber .223 / 5.56