The Primary Weapons Systems MK111 MOD 2-M is a semi-automatic AR-pattern rifle chambered in .223 Wylde, built in an 11.85-inch short-barreled configuration; transfer requires additional federal paperwork. It runs on a long-stroke piston gas system with a 3-setting adjustable regulator instead of direct impingement, and it ships with an FRC compensator and a monolithic upper receiver. 
 

Key Specifications 

• Brand: Primary Weapons Systems 
• Model: MK111 MOD 2-M 
• Caliber: .223 Wylde 
• Action: Semi Auto 
• Capacity: 30 Rounds 
• Barrel Length: 11.85 in 
• Finish: Hardcoat Anodized Black 
• Stock: Adjustable Synthetic 
   

Detailed Features 

• Long-stroke piston gas system with a 3-setting adjustable regulator cuts down on gas blowback into the action compared to direct impingement designs. 
• .223 Wylde chamber safely runs both .223 Remington and 5.56 NATO ammunition. 
• FRC compensator helps manage muzzle rise for faster follow-up shots. 
• Monolithic upper receiver provides one continuous rail for mounting optics and accessories. 
• Barrel carries a 1:8 twist rate under a hardcoat anodized black finish.

Owners of the MK111 MOD 2-M like that the long-stroke piston system keeps the action and bolt carrier noticeably cleaner than a direct impingement AR-pattern rifle over a hard range day, though a few note that piston guns like this one need their own maintenance routine and aren't always a drop-in swap with standard AR parts.

As a short-barreled configuration, the MOD 2-M is praised for staying maneuverable and easy to move through doorways or a vehicle, and the adjustable gas regulator gets credit for letting owners tune the system for suppressed or unsuppressed use. Some owners find the extra step of dialing in the regulator annoying compared to a fixed-gas AR.

PWS parts and the .223 Wylde chamber's flexibility with common ammunition are seen as strong points for long-term ownership, though the transfer process and paperwork that come with a short-barreled rifle are a real barrier for owners who would rather skip that step entirely.