Primary Weapons Systems MK116 Piston Upper (16.1" .223 Wylde Barrel)

Primary Weapons Systems MK116 Piston Upper (16.1" .223 Wylde Barrel)

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$1,349.95 $1,147.46

MPN: M116UA0B / 2M116UA0B


  • PWS Mid-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 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


  • Caliber: 5.56 NATO / .223 Rem.
  • Chamber: .223 Wylde
  • 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 PicMod Technology - Made from 6061-T6 aluminum
  • M4 Feed Ramps: Yes
  • Muzzle Device: PWS FSC556 Flash Suppressing Compensator
  • Barrel: 16.1” 1:8 Twist Modified 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: Mid-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 lbs. 9.5 oz.
    • MK116 MOD 2-M: 4 lbs. 7.8 oz.
  • Overall Length: 24.88"


  • AR-15 lower receivers


  • 1x Primary Weapons Systems MK116 Piston Upper with .223 Wylde Barrel
  • 1x PWS Rifle Service Tool





The PWS MK116 Piston Upper features a high-quality 16.1-inch stainless steel barrel chambered in .223 Wylde, it is capable of handling both .223 Rem and 5.56 NATO ammunition with great accuracy. When you marry the Wylde Chamber with an evolved long stroke piston system you get an upper that’s hard to beat at the range or in the field. The MK116 is long enough to skip the NFA short barrel circus without a muzzle device. It responds to a variety of duties and applications with commendable results, even out to 500 meters.

Advanced Reliability

The PWS MK116 is based on the innovative MK1 upper system, one of the most reliable piston AR upper on the market. The long stroke piston AR design of the PWS MK1 marries the flexibility of the AR platform with the proven reliability of the AK-47. It’s better than a genetic experiment, this is a crossbreed that works. The MK1 features advanced reliability, less intensive maintenance and excellent duty life. Since the BCG and free-floating piston system are joined with an operating rod, there are fewer individual moving parts and less opportunity for failure.

MOD-1 Vs. MOD-2

If you’re a dyed-in-the-wool forward assist guy, choose the PWS Mod 1 upper. It has plenty of advanced features that raise it above the crowd and the reliability of the long piston AR upper but it’s not such a great departure that you’ll feel alienated by your own weapon.

Those who are ready to jump into the evolution of the AR system feet first are ready to give the PWS MK1 Mod 2 a run. You won’t be disappointed. The PWS Mod 2 continues the progress made by the Mod 1 and takes another leap forward. In addition to quality surface treatments (FNC LIFE HD,) free floated M-LOK handguards, and integrated QD mounts, the PWS Mod 2 includes PWS’ own PicMOD® combination rail that accepts both Picatinny and M-LOK Accessories. The forged upper itself is trimmed down, machined down to drop weight and bulk while maintaining exceptional strength. The additional mass reduction comes from dropping the traditional forward assist which just isn’t practical when your upper cycles as reliably as the MK1. Gas management is a simple matter of choosing the correct position of three offered on the adjustable gas block, a simpler matter than the variable adjustments offered in the previous MK1’s adjustable gas block.

Either way, you climb, you’re above the competition on the evolutionary ladder. Choose a Primary Weapons Systems MK116 for your next build or upgrade. Because It’s Time.

NOTE: For the protection of our customers and various safety and legal liability reasons, we do not accept returns on ammunition, firearms, barrels, or any product that contains a barrel. Defective firearms, barrels, any product that contains a barrel (i.e., complete AR-15 uppers, complete pistol slides, etc.) and ammunition must be returned to the original manufacturer for warranty service. You can have peace of mind that all firearms, barrels, complete uppers, and ammunition that we sell are brand new from the manufacturer, and have never been used, installed, or modified.

Write a Review

1 Review

  • Very impressed

    Posted by John on 27th Oct 2019

    About 1000 rounds so far. Zero failures. Runs amazingly cleanly. Amazingly. Barrel very high quality and more accurate that I anticipated. It is really nice how much easier it is to clean the rifle over a DI system. Recoil really not much different from a good DI gun, possibly a little more noticeable. I am very pleased. Because of the ease of cleaning, it has replaced my DI upper as my go-to. Way worth it.

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