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Rainier Arms MK12 223 Wylde Partial Upper Receiver RA-MK12-DI-18R-PU Caliber: .223 Wylde, Barrel Length: 18 in, 15% Off w/ Free Shipping

Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
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Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
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Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
3 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
4 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
5 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
6 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
7 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
8 of 9 images
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU
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Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU

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Customer Reviews
Helpful Positive Review
Fantastic Upper by Mike B, Verified Owner, April 9, 2025
The MK12 upper from Rainier Arms is fantastic. It is finish is amazing and the PRI parts make this well worth the money. The match grade barrel is an amazing addition. I currently own the MK12 MOD-0 from PRI and this upper is just as well made for le...
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Caliber: .223 Wylde Barrel Length: 18 inBarrel Profile: Medium Gas System Length: Rifle Length Barrel Twist Rate: 1-8 Threads per Inch: 1/2x28 Finish: Nitride Color: Black Gun Model: AR-15 Condition: New Gas Block Journal Size-Diameter: .750 inHandguard Length: 12.5 inWeight: 6 lb

Code: 4ZM-UFH-RAAR4-RA-MK12-DI-18R-PU

MPN: RA-MK12-DI-18R-PU

UPC: 744985352081

List: $1,229.00Save 15%
$1,050.00

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 MK12 223 Wylde Partial Upper Receiver

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!image

Specifications for Rainier Arms MK12 223 Wylde Partial Upper Receiver:

Manufacturer: Rainier Arms
Caliber: .223 Wylde
Barrel Length: 18 in
Barrel Profile: Medium
Gas System Length: Rifle Length
Barrel Twist Rate: 1-8
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 Length: 12.5 in
Handguard Style: M-LOK w/ Top Picatinny Rail System
Gun Make: AR Platform
Bolt Carrier Group Included: No
Charging Handle Included: No
Weight: 6 lb
Magazine Included: No

Features of Rainier Arms MK12 223 Wylde Partial Upper Receiver

  • 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

Package Contents:

  • Rainier Arms MK12 223 Wylde Partial Upper Receiver

What firearm models does the manufacturer say Rainier Arms MK12 223 Wylde Partial Upper Receiver is compatible with?

The manufacturer suggests that Rainier Arms MK12 223 Wylde Partial Upper Receiver is compatible with AR-15

Rainier Arms MK12 223 Wylde Partial Upper Receiver Orderable Models

List of Orderable Models

  • Rainier Arms MK12 223 Wylde Partial Upper Receiver, Black, 18 in, RA-MK12-DI-18R-PU , MPN: RA-MK12-DI-18R-PU , UPC: 744985352081 , Code: 4ZM-UFH-RAAR4-RA-MK12-DI-18R-PU
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