MPN: 2M118UA0B


  • 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: Forged Lightweight Flat Top Upper (No forward assist) - Made from 7075-T6 aluminum
  • Handguard: 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: 18” 1:8 Twist Modified Low-Stress profile .223 Wylde 41V50 CMV Barrel with FN HD Life Treatment
  • 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: ~4 lb. 11 oz.
  • Overall Length: ~26.94"


  • AR-15 lower receivers


  • 1x Primary Weapons Systems MK118 Piston Upper with .223 Wylde Barrel
  • 1x PWS Rifle Service Tool





If you’re looking for a reliable, high-end AR-15 upper with and 18-inch barrel look no further than the Primary Weapons Systems MK118 Upper. The MK118 is a quality long stroke piston upper that has proven reliable for multiple applications. This upper features the advanced .223 Wylde chamber which offers accuracy with a variety of .223 Rem and 5.56 NATO ammunitions.

Design Evolution

The PWS MK118 Upper is an advanced design MK1 upper from Primary Weapons Systems. The MK1 upper combines the long term reliability of the AK-47 with the operator friendly flexibility of the AR platform. The result is a long stroke piston upper that has an amazing service life with greater reliability and less opportunity for individual parts failure than most AR Upper on the market. The secret is the union of the bolt carrier group and free-floating piston head. A simple operating rod joins the two pieces, creating a single operating unit that is far easier to maintain than impingement systems. It requires far less attention in the field because it is not as susceptible to the effects of fouling than traditional AR Uppers.

Next Gen Features

If you’re ready to take full advantage of the evolution of modern weaponry, you need to get your hands on a PWS MK118 Upper. Like the rest of PWS’ awesome MK1 MOD 2 line, the MK118 features FNC LIFE HD surface treatments, integrated quick disconnect mounts, Picatinny upper rails and the ultra-flexible PicMOD® rail which provides a functional accessory mounting surface for both Picatinny and M-LOK accessories. gas management is enhanced by a simple three position selector that helps provide optimum pressure with whatever ammunition you choose.

Lightweight Forged Uppers

The MK1 Mod 2 Upper is a forged upper with a difference. Primary Weapons Systems doesn’t forge it and forget it. This Upper is forged and then precision machined to remove excess material, creating a sleeker, lighter upper that retains the incredible strength of a forged upper. The reliability of the long piston upper allows PWS to further reduce mass by dropping the forward assist altogether for a more streamlined silhouette.

It’s Time

You don’t want to stagnate, you want to evolve and move ahead of the pack. Choose the PWS MK118. Primary Weapons Systems, Because It’s Time.

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