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Primary Weapons Systems MK111 Mod-1M Upper, Fits AR15, 223 Wylde 11.85" Barrel

Primary Weapons Systems MK111 Mod-1M Upper, Fits AR15, 223 Wylde 11.85" Barrel

SKU: PWSMK11111.85

Text / Email for best price :) THIS ITEM IS IN STOCK AT OUR WAREHOUSE. By purchasing this item you understand it will ship in approximatley 3-5 days, at the discretion of the mail services and their delivery rates. Please feel free to reach out with any questions via call/text/ or email.


UPC 811154030351


The MK1 MOD 1-M line, revamped for 2018, features the PWS long stroke piston system. Internally, this line offers the tried and true system that PWS owners have grown to know and love. Featuring a free-float MLOK handguard, forward assist controls, and a more true to mil-spec design, the MK1 MOD 1-M line is a go-to for not only civilians, but also Law Enforcement. With fully forged receivers, the MK1 MOD 1-M is a no-nonsense tool for when you need a high value option that is relentless and unstoppable.



  • PWS carbine-length long-stroke piston system - combines the agility of the AR-15 with the reliability of the AK-47 into a sleek and efficient design
  • 3 easy to adjust gas settings
  • Continuous Picatinny top rail
  • Free Float M-LOK rail system w/ PicMod Technology in MOD 2 models - The new technology allows you to mount M-LOK attachments anywhere on your handguard and mount Picatinny accessories directly to the recessed Picatinny rail section at the end of the handguard
  • Light-weight forged upper in MOD 2 models - No forward assist and material removed from less structurally important location for weight reduction
  • Increased carrier mass to extend dwell time and delay unlock
  • Lithium Embedded Salt Nitro-Carburized (FNC LIFE HD) coated barrel and bolt carrier for durability, corrosion resistance and to reduce friction


*This upper receiver assembly has a barrel that is shorter than 16". This upper is only for use on AR pistol lower receivers and NFA registered Short-Barreled Rifle (SBR) lower receivers. All NFA laws apply!



  • Caliber: 5.56 NATO / .223 Rem.
  • Chamber: .223 Wylde
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver:
    • MK111 MOD 1-M: Forged Flat Top Upper - Made from 7075-T6 aluminum
  • Handguard:
    • MK111 MOD 1-M: 11-inch M-LOK Rail System - Made from 6061-T6 aluminum
  • M4 Feed Ramps: Yes
  • Muzzle Device: PWS Triad 556 flash suppressor
  • Barrel: 11.85” 1:8 Twist Modify Low-Stress profile .223 Wylde 416R Stainless Steel Barrel (Black finish)
  • Muzzle Thread Pattern: 1/2"-28
  • Gas Block: PWS Long Stroke Piston System - 3-Position Adjustable Gas Block
  • Gas Length: Carbine-Length
  • Bolt Carrier Group: PWS Long Stroke Piston Bolt Carrier Group
  • Charging Handle: Radian Raptor-LT Ambi Charging Handle
  • Weight:
    • MK111 MOD 1-M: ~4 lbs. 1 oz.
  • Overall Length: ~20.5"



  • Any Mil-Spec AR-15 lower receiver


Those operators who rely heavily on the use of suppressors have long been wary of changes to the standard rifle system they have long depended on. Today, Primary Weapons Systems offers a long piston AR upper to work with their weapon systems. The PWS MK111 is a fully assembled long piston operated upper with an 11.85 inch .223 Wylde Barrel that was designed especially for use with the shortest working suppressed rifle systems. The MK111 had been successfully battle tested in a number of arenas and has proven lethal at up to 300 meters.

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