The Primary Weapons Systems PWS MK116 MOD 2-M Upper 338ARC 16.1 LS FRC Comp is a dedicated upper receiver assembly designed for shooters who want to run the 338 ARC cartridge on a proven PWS long-stroke piston platform. Built around the MK1 MOD 2-M architecture, this upper offers a balanced 16.1-inch barrel paired with a factory muzzle compensator to help manage recoil and maintain flat, predictable tracking shot to shot.

This upper is ideal for enthusiasts looking to upgrade an existing lower for range use, training, or hunting with the versatile 338 ARC round. The long-stroke piston system is engineered to deliver smooth cycling and reduced fouling compared to traditional direct-impingement setups, supporting consistent performance over extended shooting sessions. Backed by Primary Weapons Systems’ reputation for innovative gas piston designs and attention to detail, the MK116 MOD 2-M Upper provides a refined foundation for a capable modern rifle build.

• Manufacturer: Primary Weapons
• Model: PWS MK116 MOD 2-M Upper 338ARC 16.1 LS FRC Comp
• Finish: Black
• Category: Assembled Upper Receiver
• Feature: 16.1" Barrel