The Primary Weapons Systems MK2 Mod 2 is a semi-automatic AR-style rifle chambered in .308 Win (7.62x51 NATO). It runs PWS's long-stroke piston system with an adjustable gas block and pairs a 16.1-inch stainless steel barrel with a PWS FRC compensator. The rifle ships with an M-LOK handguard, a 20-round magazine, and Magpul furniture. 
 

Key Specifications 

• Brand: Primary Weapons Systems 
• Model: MK2 Mod 2 
• Caliber: .308 Win 
• Action: Semi-Auto 
• Capacity: 20+1 
• Barrel Length: 16.1" 
• Barrel Material: Stainless Steel 
• Twist Rate: 1:10" 
• Trigger: Mil-Spec 
   

Detailed Features 

• Long-stroke gas piston operating system with an adjustable, three-setting gas block for tuning reliability across different ammunition. 
• 16.1-inch barrel fitted with a PWS FRC compensator to manage recoil and muzzle rise. 
• M-LOK handguard for mounting lights, grips, and other accessories directly to the rail. 
• Ambidextrous controls and a PWS Enhanced grip support use from either shoulder. 
• Ships with a Magpul stock and grip for adjustable length of pull and a non-slip shooting interface.

Owners of the MK2 Mod 2 tend to like PWS's piston system for staying cleaner inside than a direct-impingement .308 AR, and reliability reports are generally positive once the adjustable gas block is dialed in for the ammunition being run. A few new owners note the piston setup has a learning curve compared to a simpler DI rifle, and that the added mechanism adds a bit of weight up front.

Ergonomics get favorable comments thanks to the Magpul stock and grip and the ambidextrous controls, which left-handed shooters in particular appreciate. The M-LOK handguard makes it easy to add lights, slings, and grips without extra adapters, though some shooters wish the handguard ran a bit longer for more accessory space.

On value, the MK2 Mod 2 sits at a premium price point relative to many .308 AR-style rifles, and owners generally feel the piston system and FRC compensator justify the cost for anyone planning heavy use or suppressor work. The AR-pattern lower keeps aftermarket grips, triggers, and optics mounts widely compatible.