MPN: M116UB0B / 2M116UB0B


  • PWS long-stroke piston system - combines the agility of the AR-15 with the reliability of the AK-47 into a sleek and efficient design
  • Continuous Picatinny top rail
  • Free Float M-LOK system w/ PicLok 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


  • Caliber: 300 Blackout
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver:
    • MK116 MOD 1-M: Forged Flat Top Upper - Made From 7075-T6 Aluminum
    • MK116 MOD 2-M: Forged Lightweight Flat Top Upper (No Forward Assist) - Made From 7075-T6 Aluminum
  • Handguard:
    • MK116 MOD 1-M: 15-inch M-LOK Rail System - Made From 6061-T6 Aluminum
    • MK116 MOD 2-M: 15-inch M-LOK Rail System with PicLok Technology - Made From 6061-T6 Aluminum
  • M4 Feed Ramps: Yes
  • Muzzle Device: PWS .30 Cal FSC Flash Suppressing Compensator
  • Barrel: 16.1” 1:8 Twist Modified Low-Stress Profile 300 Blackout 41V50 CMV Barrel with FN HD Life Treatment
  • Muzzle Thread Pattern: 5/8"-24
  • Gas Block: PWS Long Stroke Piston System - 3-Position Adjustable Gas Block
  • Gas Length: Pistol-Length
  • Bolt Carrier Group: PWS Long Stroke Piston Bolt Carrier Group
  • Charging Handle: Radian Raptor-LT Ambi Charging Handle
  • Weight:
    • MK116 MOD 1-M: ~4.32 lbs.
    • MK116 MOD 2-M: ~4.15 lbs.
  • Overall Length: ~25.5"


  • Any Mil-Spec AR-15 lower receiver


  • 1x PWS MK116 Piston Upper with 300 Blackout Barrel
  • 1x PWS Rifle Service Tool




Primary Weapons Systems brings the PWS MK116 300 Blackout Upper to the market for those of us who are ready to take a giant leap forward with a quality 300 Blackout piston system upper. The 16.1-inch barreled version of the PWS 300 Blackout piston upper allows for operation in a great number of varying operating environments and proves itself lethal out to the 500-meter mark with a variety of ammunition types. It has proven itself reliable in the field and is sure to impress those who are new to the advanced design of PWS’ long piston upper systems.

Why Choose PWS 300 Blackout Upper

When engineers at PWS went to the drawing board to create the MK1 piston driven upper, the creative minds at Primary Weapons Systems sought to marry the legendary reliability of the AK-47 with the ergonomic advances and flexibility of the AR platform. If you try a PWS MK116 you’ll find that they have succeeded in creating an extra-reliable long stroke piston operated upper that adapts well to chambering in 300 Blackout and the variety of operating conditions.

Fewer moving parts and less susceptibility to the effects of fouling allows the PWS MK1 upper to work long after impingement systems have succumbed to wear, broken parts and the inevitable failures caused by poor maintenance. The MK1 upper relies on a single unit operating component created by connecting the Bolt Carrier Group to a Floating Piston with an Operating Rod. This creates a single moving unit from three parts that would be interdependent in function yet able to fail individually in previous generations of uppers. The reliable function of this system is less vulnerable to the effects of soot and other forms of fouling than its predecessors too. That frees you up to do the real work in the field rather than keeping your hands tied cleaning a firearm that isn’t happy unless it’s enslaved you in a cycle of eternal maintenance issues.

PWS MK1 Mod 1 and MK1 Mod 2 Piston Operated AR-15 Upper

You have the option of choosing a more traditional looking PWS MK1 Mod 1 upper, which is a little heavier than the PWS MK1 Mod 2 and retains the forward assist that’s been left off of the Mod 2. The PWS MK1 Mod 1 is no slouch, with advanced features that leave competitors in the dust without taking the traditional AR fan too far from his comfort zone. If you like the confidence you get from the ritual of tapping that forward assist we're more than happy to oblige and wrap it up in a package with a piston operated 300 Blackout upper featuring free floated handguards with QD attachments and ample M-LOK slots.

If you're ready to move even further ahead of the pack, let us suggest the PWS MK1 Mod 2. It's all that and exclusive PWS PicMOD® rail that accepts both Picatinny and M-LOK accessories. The receiver itself has been put on a diet, shedding excess ounces of material to the bite of the CNC while retaining its strength. The forward assist is also a thing of the past on the PWS MK1 Mod 2. Given the reliability of the long piston system, we're confident you just won't miss it.

Because It's Time. Strength Through Evolution. The Primary Weapons Systems MK116 300 Blackout.

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