The Primary Weapons Systems MK116 Mod 2-M is a semi-automatic AR-pattern rifle chambered in .223 Wylde with a 16.1-inch barrel. It runs a long-stroke piston operating system and ships with one 30-round magazine. An FRC compensator is included at the muzzle. 
 

Key Specifications 

• Brand: Primary Weapons Systems 
• Model: MK116 Mod 2-M 
• Caliber: .223 Wylde 
• Action: Semi Auto 
• Capacity: 30 rounds 
• Barrel Length: 16.1 inches 
• Color/Finish: Black 
   

Detailed Features 

• Long-stroke piston operating system 
• FRC compensator at the muzzle 
• 16.1-inch barrel 
• Ships with one 30-round magazine 
• .223 Wylde chamber accepts both .223 Rem and 5.56 NATO

Owners of the PWS MK116 Mod 2-M consistently point to the long-stroke piston system as the defining trait of the platform. Compared to direct-impingement AR rifles, users report the action runs notably cooler and cleaner during extended sessions, which owners with high round counts appreciate.

The FRC compensator gets mixed feedback. Some shooters find it very effective at muzzle rise reduction; others find the concussion at close range a drawback when shooting in covered positions. Swapping the comp is straightforward, and the .223 Wylde chamber is broadly seen as a smart choice for a versatile range rifle.

At a price point above standard AR builds, the MK116 Mod 2-M is seen by most owners as a premium but justifiable buy. The complaint that surfaces occasionally is weight: piston AR rifles are heavier than their DI equivalents, and some buyers note the MK116 feels it compared to lighter carbines.