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Rainier Arms, LLC

Rainier Arms Mountain Upper Receiver

Rainier Arms Mountain Upper Receiver
Only 5 left

Availability: In stock




Description: Rainier Arms Custom

Our Rainier Arms Mountain Series upper receiver group was designed for the enthusiast that's looking for a solid foundation for their next upper build using our 16" 1:7 twist Mountain series barrel, our Mil-Spec upper receiver group and Lo Profile gas block. The rest is entirely up to the customer and can be easily built out.

Does NOT come with a BCG, Muzzle device, Charging handle or handguard. Component List:

  • Rainier Arms Mountain Mid Weight Series 16" Barrel, Midlength Gas System with 1:7 Twist
  • Rainier Arms Match Lo Pro gas block
  • Rainier Arms Forged A4 Upper Receiver- GEN2 with UPK
  • Rainier Arms Barrel nut
  • Gas tube
  • Weight: 2lbs 7oz

Additional Info

Additional Info

SKU RA1500
Manufacturer Rainier Arms, LLC
Finish No
Barrel Length No
Caliber No
Configuration No
Option No
Gas Length No
Height No
Rail Length No
Mount No
Profile No
Reticle No
Co Witness No
Size No


Customer Reviews (2)

QualityReview by
I was impressed how quickly Rainier Arms got my upper to me. This upper was exactly what I was looking for to complete my AR build. Reasonably priced for a quality product. Will do business with Rainier Arms again. (Posted on 2/16/2017)
Great Product Review by
As most of us know, Rainier Arms is a great company producing great products. I was torn between the Mountain and the Select barrels, then finally decided on the the Mountain. Then I realized the offered it halfway finished, and figured 'why not', since I know they make great stuff. Saved me time, effort and some money. Long story short, the barrel (combined with other variables) is a tack driver. Everything I shoot (55gr-69gr) is spot in. The fitment and finish goes without saying, because it's perfect. I have only 1k rounds through it, and it's just warming up! Thanks Rainier (Posted on 2/17/2016)

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