Primary Weapons Systems MK109 Features The Primary Weapons Systems MK109 upper is engineered around the company s proven long stroke piston operating system which keeps hot gas out of the receiver and reduces the fouling that plagues direct impingement guns meaning longer intervals between cleanings and more consistent cycling under hard use. The 9.75 barrel is cut with a 1:8 twist to stabilize the heavier bullet weights that make .300 Blackout effective at both suppressed subsonic and supersonic velocities and the PWS Triad muzzle device manages recoil impulse and muzzle rise for faster more accurate follow-up shots. Eliminating the forward assist and adding a flared magwell and built-in trigger guard streamlines the manual of arms without sacrificing reliability. Shooters running suppressors or seeking a purpose-built short-barrel carbine benefit most from this piston-driven twist-matched barrel combination. The 8.9 PWS PicLok M-LOK handguard uses patent pending PicLok technology letting users bolt on Picatinny sections or M-LOK accessories anywhere along the free float rail without giving up the slim ergonomic profile. A fully forged upper receiver delivers tight tolerances and a durable anodized black finish that resists wear and corrosion in the field. The included Radian Raptor ambidextrous charging handle gives left and right-handed shooters equally fast snag-free manipulation a meaningful upgrade over a standard mil-spec handle. Together these details make the MK1 MOD 2-M upper a compact accessory-ready package suited to serious range use home defense and duty-style applications alike. Primary Weapons Systems MK109 MOD 2-M Specifications Brand: Primary Weapons Systems Model: MK109 MOD 2-M Type: Complete Upper Receiver Caliber: .300 AAC Blackout Barrel Length: 9.75 Twist Rate: 1:8 Fit: AR-15 Handguard: 8.9 PWS PicLok M-LOK Muzzle Device: PWS Triad Finish: Anodized Color: Black Includes: Radian Raptor Ambidextrous Charging Handle Available At: GrabAGun