Primary Weapon Systems MK111 PRO Complete Upper .223 Wylde Gas Piston - 11.85"

SKU: 19-PM111UA0B
MPN: 19-PM111UA0B
Manufactured by Primary Weapon Systems


In Stock

We are fully staffed and processing orders. Standard orders are shipping in approximately 1 business day. FFL orders take approximately 7 business days if you can provide us an actively receiving FFL location.


In Stock


NOTE: This upper receiver has a barrel that is less than 16” in length and is intended for use in AR pistol or legal short-barreled rifle builds. Other configurations may violate Federal law.

For those looking to build an AR pistol or SBR that is different from your standard AR-15 platform, Primary Weapon Systems has you covered. The PWS MK111 PRO Complete Upper Receiver features a 3-position adjustable long stroke gas piston system for the ultimate in reliability and smooth function. The gas block adjustment switch is easily accessible through the free float M-LOK handguard, so you can quickly add picatinny rails or M-LOK accessories. The barrel is machined from 416R stainless steel and features a .223 Wylde chamber for extreme accuracy potential. Additionally, the 11.85” barrel is button rifled with a 1:8 twist rate and has an effective A2 flash hider. Change up your AR collection with the PWS MK111 PRO Piston Upper.

  • 3 Position adjustable long stroke gas piston
  • Mid-Length piston system
  • 11.85” barrel chambered in .223 Wylde
  • 416R stainless steel and Nitride finished
  • A2 Flash Hider
  • Button rifled 1:8 twist rate
  • Proprietary slick side upper and BCG
  • Forged 6061-T6 aluminum
  • Radian Raptor charging handle
  • 11" M-LOK free float handguard
  • Weight: 4 lbs. 2 oz.

The proprietary piston upper receiver is forged from 6061 aluminum and features a slick side design with an M4 flat top Picatinny rail for easily mounting optics. Even though it uses a proprietary upper and bolt carrier group, it is still compatible with AR-15 charging handles like the ambidextrous Radian Raptor.

The mission at Primary Weapons Systems is to provide the highest quality tactical and sporting rifles and accessories for sportsmen, military, and law enforcement at a fair, competitive price.


Barrel ContourMedium
Barrel Length11.85
Barrel Material416R Stainless Steel
BrandPrimary Weapon Systems
Gas System LengthMid-Length
Gas System TypeLong Stroke Gas Piston
Handguard11 in M-LOK Rail
Muzzle DeviceA2 Flash Hider
Twist Rate1:8

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