Primary Weapons MK114 MOD 2-M 6mm ARC 14.5" Piston AR-15 Complete Upper

The Primary Weapons MK114 MOD 2-M is a complete AR-15 upper receiver assembly chambered in 6mm ARC and built around PWS's long-stroke piston operating system. Purpose-built for long-range performance, this upper delivers flat trajectories and reduced recoil while retaining the familiar AR-15 manual of arms.

At the heart of the upper is a 14.5" barrel paired with PWS's proven long-stroke piston drive, which routes propellant gases through a dedicated piston and rod rather than the traditional direct-impingement tube. The piston system is widely regarded for its reliability in adverse conditions and its ability to reduce fouling reaching the bolt carrier group, keeping the action running cleaner over extended shooting sessions.

The MK114 MOD 2-M upper features a lightweight forged build engineered to produce a maneuverable, well-balanced package well-suited to long-range precision work without sacrificing handling. It drops onto any standard AR-15 lower receiver, making it a straightforward upgrade or platform builder for shooters looking to expand into the 6mm ARC cartridge.

The 6mm ARC chambering is highlighted by flat trajectories and reduced recoil, making it well-suited to long-range precision applications while maintaining the handling characteristics of the AR-15 platform.

This listing is for the complete upper receiver assembly only, including the barrel, gas system, handguard, and upper receiver housing. A lower receiver is required for function and is not included.