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Rainier Arms RUC PRO MK1 5.56 NATO Partial Upper Receiver

AR-15 Partial Upper Receiver

In stock


Rainier Arms RUC PRO MK1 5.56 NATO Partial Upper Receiver

$550.00 - $625.00

Introducing the RUC PRO MK1 Partial Upper. Bringing the highest quality parts to the market, while offering the best value as well. This partial upper utilizes a Rainier Arms Low Pro nonadjustable gas block on our new and improved Rainier Arms Select barrel. Pairing up with new PRO series MK1 handguard to provide shooters with a rock solid handguard that can take any abuse. Throw in your favorite charging handle and bolt carrier group and you are good to go!



10.5" Upper:

  • Rainier Arms Select 5.56 NATO Barrel - 10.5"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK1 Handguard - 9.55"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable) (Gasblock pinned)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Carbine Gas Length
  • Weight: 2 lbs 14 oz



11.5" Upper:

  • Rainier Arms Select 5.56 NATO Barrel - 12.5"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK1 Handguard - 11.7"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable) (Gasblock pinned)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Weight: 3 lbs 2.6 oz



12.5" Upper:

  • Rainier Arms Select 5.56 NATO Barrel - 12.5"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK1 Handguard - 11.7"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable) (Gasblock pinned)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Weight: 3 lbs 2.6 oz



14.5" Upper:

  • Rainier Arms Select 5.56 NATO Barrel - 14.5"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK1 Handguard - 13.7"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable) (Gasblock pinned)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Weight: 3 lbs 8.4 oz



16" Upper:

  • Rainier Arms Select 5.56 NATO Barrel - 16"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK1 Handguard - 15"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable) (Gasblock pinned)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Weight: 3 lbs 12.6 oz



Please NOTE: BCG and Charging Handle NOT Included.

More Information
SKU RA-RUC-PRO-MK1-XX-PU-BLK
Product Type AR-15 Partial Upper Receiver
Manufacturer Rainier Arms, LLC
Gas Block Diameter .750"
Thread Pitch 1/2x28 (.22 cal)
Color Black
Mount M-LOK
Platform AR-15
Caliber 5.56 NATO
Threaded Yes

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