+1-800-504-5897 Help Center Check Order Status
About Us Policies Reviews How To
Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Enjoy free shipping during the holidays! Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC and to all U.S. Military APO/FPO/DPO addresses.

Enjoy Our Extended FREE RETURNS

We want to ensure that making a return is as easy as possible! With our Hassle-Free, Extended Holiday Returns, eligible orders placed from November 12, 2025 on will benefit from an extended return deadline (January 13, 2026 or 30 days after receipt of your order - whichever is later). We'll even cover the cost of return shipping. Learn more about our Return Policy.

  • Entire Store
  • ...
  • Apparel & Footwear
  • Astronomy
  • Everything Else
  • Eyewear
  • Hunting Gear
  • Lab Equipment
  • Military Gear
  • Outdoor Gear
  • Photography Equipment
  • Police, EMS & Fire
  • Shooting
  • Sport Optics
  • Sports & Hobbies
TIP
Shopping Cart

Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver Up to $20.00 Off w/ Free S&H — 4 models

Special offer available for this product. Click here to see!
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
1 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
2 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
3 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
4 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
5 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
6 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
7 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
8 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
9 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
10 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
11 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
12 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
13 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
14 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
15 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
16 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
17 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
18 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
19 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
20 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
21 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
22 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
23 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
24 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
25 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
26 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
27 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
28 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
29 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
30 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
31 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU
32 of 32 images
Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU

Tap Tap to Zoom

Government Export Restriction Government Export Restriction
Government Restriction Government Restriction
Questions & Answers
Show In Stock Only
4 Models Available
Barrel Length
All
Gas System Length
All
Barrel Twist Rate
All
Handguard Length
All
Weight
All
Search

ATTENTION! We currently do not ship this product to AK, CA, HI, IL, NY, WA, P.O. Boxes, and U.S. Territories. Please see our policies for more information.

Product Info for Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver

Introducing the RUC PRO MK2 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 MK2 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!image

Specifications for Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver:

Manufacturer: Rainier Arms
Caliber: 5.56x45mm NATO
Barrel Profile: Medium
Threads per Inch: 1/2x28
Finish: Nitride
Color: Black
Gun Model: AR-15
Condition: New
Fabric/Material: 416R Stainless Steel Nitrided
Gas Block Journal Size-Diameter: .750 in
Handguard Style: M-LOK w/ Top Picatinny Rail System
Gun Make: AR Platform
Bolt Carrier Group Included: No
Charging Handle Included: No
Magazine Included: No

Features of Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver

  • Rainier Arms Select 5.56 NATO Barrel - 10.5"
  • Rainier Arms Forged Upper Receiver
  • Rainier Industries PRO Series MK2 Quad-Rail Handguard - 9.55"
  • Rainier Arms Low Pro Gas Block - .750" (Non-adjustable)
  • Rainier Industries .223/5.56 Flash Hider - 1/2x28
  • Weight: 3 lbs 3.4 oz

Package Contents:

  • Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver

What firearm models does the manufacturer say Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver is compatible with?

The manufacturer says that Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver is compatible with AR-15

Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver Orderable Models

List of Orderable Models

  • Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12 in, RA-RUC-PRO-MK1-RS-12-PU , MPN: RA-RUC-PRO-MK1-RS-12-PU , UPC: 744985352159 , Code: 4ZM-UFH-RAAR6-RA-RUC-PRO-MK1-RS-12-PU
  • Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 11.5 in, RA-RUC-PRO-MK1-RS-115-PU , MPN: RA-RUC-PRO-MK1-RS-115-PU , UPC: 744985352142 , Code: 4ZM-UFH-RAAR6-RA-RUC-PRO-MK1-RS-115-PU
  • Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 10.5 in, RA-RUC-PRO-MK2-105-PU , MPN: RA-RUC-PRO-MK2-105-PU , UPC: 744985352128 , Code: 4ZM-UFH-RAAR6-RA-RUC-PRO-MK2-105-PU
  • Rainier Arms Ruc Pro Mk2 5.56 Nato Partial Upper Receiver, Black, 12.5 in, RA-RUC-PRO-MK2-125-PU , MPN: RA-RUC-PRO-MK2-125-PU , UPC: 744985352135 , Code: 4ZM-UFH-RAAR6-RA-RUC-PRO-MK2-125-PU
Compare (0)
1 item has been added
Add at least two items to compare