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Questions & Answers
What steel is the barrel made from

Current production barrels are 41V50 steel.

by Geno, Verified Owner, September 14, 2022
is this upper rated for 5.56

223 wylde, so yes, you can shoot 556 and 223, but you would "maximize" efficiencies by using 223

by Phil, Verified Owner, January 7, 2022
Customer Reviews
Helpful Positive Review
let me slurp by eric, Verified Owner, April 17, 2023
Well, had to wait 40 days, but im not even mad. PWS MK111 MOD2 is the best purchased ive ever made on opticplanet. I can't believe how light it is. It feels like my MCX upper is twice as heavy in comparison. The technology is worth every penny. The b...
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6/6 found this helpful
Helpful Positive Review
Money well spent. Handles .223 & 5.56, 55-77gr very nicely.
2/3 found this helpful
Helpful Positive Review
Great suppressor host by Cool muzzle device, Verified Owner, March 15, 2025
Fantastic upper, very soft shooting on the 2nd gas setting with my Flow556k on it. Nice compact Pisol ;) that I plan on SBRing my lower for it. Fit and finish is great with almost no movement when attached to my Aero lower. This is my third PWS upper...
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2/2 found this helpful
Helpful Positive Review
PWS MK111 MOD2 by Dukes, Verified Owner, September 26, 2021
What can I say better that hasn't been said before about Primary Weapon Systems? By far the best company out there manufacturing quality products such as gas piston uppers and lowers. I paired the PWS MK111 MOD-2 Upper (11.85in) up with my Factory PW...
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9/9 found this helpful
Most Recent Reviews
Design has known flaws by j-dizzle, Verified Owner, February 13, 2026
At about 1500 round Mark I started noticing issues. The accuracy was terrible and the interior finishing was coming away. B they have many rifles and I’m able to shoot from one to 3MOA with reference ammo. This thing was shooting above 6MOA, sometim...
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Most Recent Reviews
Works great as a pistol upper! by Zach, Verified Owner, May 4, 2025
Finally decided which direction to go for my pistol build. Wanted something light weight and even though this is a little heavier than I originally planned, the long stroke piston doesn’t add too much weight. I liked the idea of this over the DI syst...
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Read All 6 Reviews
Caliber:
.223 Wylde
Barrel Length:
11.85 in
Gas System Length:
Carbine Length
Firearms Threads Per Inch:
1/2x28
Muzzle Device:
PWS Triad 556
Finish:
Matte
Color:
Black
Handguard Length:
11.85 in
Condition:
New

Code: 2D5-URC-RG27D-MK1-M2U-223-11

MPN: MK1-M2U-223-11

UPC: 811154033208

List: $1,499.95Save $100.00
$1,399.95

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Product Info for Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver

When shopping for AR15 Upper Receivers, one of the most versatile calibers available is .223 Wylde. For AR 15 pistols, the Primary Weapons Systems MK111 MOD2-M 11.85 inch .223 Wylde Upper Receiver is exactly what you need. IF you're unfamiliar with .223 Wylde, this caliber means the upper receiver is rated to handle both .223 Remington and the higher-pressure 5.56x45mm NATO, giving you a wide range of ammo versatility. Even though these types of ammo are the same caliber, the difference in pressure can damage some weapons, so you need something chambered in .223 Wylde.image

The MK111 MOD2-M is slightly longer than other AR 15 pistols, it is still short enough to give you incredible maneuverability in tight environments. Plus, since .223 Wylde is a rifle caliber, it needs a slightly longer barrel to fully burn the powder in your round and ensure proper accuracy. And, with the included Triad 556 flash hider, you don't have to worry about a blinding fireball with each shot.

WARNING: California`s Proposition 65

Specifications for Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver:

Manufacturer: Primary Weapons Systems
Caliber: .223 Wylde
Barrel Length: 11.85 in
Gas System Length: Carbine Length
Firearms Threads Per Inch: 1/2x28
Muzzle Device: PWS Triad 556
Finish: Matte
Color: Black
Fabric/Material: 7075 Aluminum
Handguard Length: 11.85 in
Gun Rail: M-LOK, Picatinny
Weight: 3.875 lb
Condition: New
Gas System Type: Long-Stroke Piston
Magazine Included: No

Features of Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver:

  • PWS Long Stroke Piston System: Renowned for reliability and reduced fouling, with adjustable gas settings for optimal performance.
  • Suppressor Optimized: Provides enhanced suppressor performance by minimizing back pressure, reducing gas blowback, and optimizing gas flow for a cleaner and more comfortable shooting experience.
  • .223 Wylde Chambering: Meticulously designed for outstanding accuracy and reliability, accommodating both .223 Remington and 5.56mm NATO.
  • Lightweight Design: The MK111 upper weighs just 4 lbs, ensuring superior maneuverability without compromising performance.
  • Barrel: 11.85" .223 Wylde barrel with a 1:8 twist rate, delivering exceptional accuracy and versatility when firing both .223 Remington and 5.56mm NATO rounds.
  • PWS FRC 2-Port Compensator: A suppresor compatible compensator that expertly mitigates recoil, muzzle rise and is compatible with the Rearden Atlas suppressor mounting system.
  • Innovative PicLokâ„¢ Handguard: Combining both Picatinny and MLOK into one for mounting accessories, balancing ergonomics and functionality.
  • Radian Raptor Ambidextrous Charging Handle: Ensures smooth operation for both left and right-handed shooters.

Package Contents:

  • Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver

Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver Orderable Models

List of Orderable Models

  • Primary Weapons Systems MK111 MOD2-M Upper Receiver, .223 Wylde, 11.85 inch Barrel, Matte, Black, MK1-M2U-223-11 , MPN: MK1-M2U-223-11 , UPC: 811154033208 , Code: 2D5-URC-RG27D-MK1-M2U-223-11

Primary Weapons Systems MK111 MOD2-M, .223 Wylde, 11.85 in Upper Receiver Unavailable & Discontinued Models

List of Unorderable Models

  • USED DEMO, Primary Weapons Systems MK111 MOD2-M Upper Receiver, .223 Wylde, 11.85in bbl, Black, 18-2M111UA0B, EDEMO1, Condition Parts Only/Salvage, Wrong Product , MPN: 18-2M111UA0B-DEMO-EDEMO1 , Code: 2D5-URC-RG27D-18-2M111UA0B-DEMO-EDEMO-WP-F
  • DEMO, Primary Weapons Systems MK111 MOD2-M Upper Receiver, .223 Wylde, 11.85in bbl, Black, 18-2M111UA0B , MPN: 18-2M111UA0B-DEMO , Code: 2D5-URC-RG27D-18-2M111UA0B-DEMO
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