The Primary Weapons Systems MK109 Mod 2-M Upper 300BLK 9.75" is a compact, complete upper receiver built around PWS’s proven long stroke piston system. Featuring a 9.75" .300 Blackout barrel capped with the PWS Triad 30 muzzle device and an 8.9" PicLok handguard, this upper offers a clean-running, suppressor-optimized platform that accepts both Picatinny and M-LOK accessories. The forged piston upper is finished in durable black anodizing and ships with a Radian Raptor ambidextrous charging handle for smooth, intuitive operation.

This MK109 Mod 2-M upper is ideal for AR-15 pistol builds or NFA short-barreled rifle configurations where maneuverability and reliability matter. Its 1:8 twist barrel is designed to stabilize a wide range of .300 BLK loads, from subsonic to supersonic, making it well suited for range use, training, and general-purpose defensive setups when paired with a compatible lower. Thoughtful details like the PicLok handguard and adjustable gas system reflect Primary Weapons Systems’ focus on practical innovation and refined craftsmanship.

Key Features:

• Manufacturer: Primary Weapons Systems
• Model: MK109 Mod 2-M Upper
• Caliber: 300 AAC Blackout
• Barrel Length: 9.75"
• Twist Rate: 1:8
• Muzzle Device: PWS Triad 30
• Handguard: 8.9" PWS PicLok M-LOK
• Operating System: PWS Long Stroke Piston, Adjustable Gas
• Charging Handle: Radian Raptor Ambidextrous
• Receiver Style: Complete Upper Receiver