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Rainier Arms MK12 223 Wylde Partial Upper Receiver - 18"

AR-15 Partial Upper Receiver

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Rainier Arms MK12 223 Wylde Partial Upper Receiver - 18"


Introducing a cloned upper receiver build of the MK12 SPR. Bringing the highest quality parts to the market, while offering the best value as well. This partial upper build utilizes a Precision Reflex GEN III free float handguard and front sight. Pairing up with our forged upper receiver and Ultramatch MOD 2 SPR 18" barrel. Throw in your favorite charging handle and bolt carrier group and you are good to go!

Upper Build:

  • Rainier Arms Forged A4 Upper Receiver
  • Rainier Arms Ultramatch MOD 2 MK12 SPR .223 Wylde Barrel - 18"
  • Precision Reflex Inc Carbon Fiber Free Float Handguard - 12.5"
  • Precision Reflex Inc G1 Flip Up Front Sight w/ .750 Crossbolt
More Information
Product Type AR-15 Partial Upper Receiver
Manufacturer Rainier Arms, LLC
Gas Block Diameter .750"
Color Black
Rail Length 12.5"
Barrel Profile SPR
Barrel Length 18"
Caliber .223 Wylde

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