Primary Weapons Systems MK109 MOD 1-M Upper Features The Primary Weapons Systems MK109 MOD 1-M Upper is built around the PWS long stroke piston system an operating design that keeps combustion gases out of the receiver for cleaner more reliable cycling than a standard direct impingement upper. Its 9.75 inch 1:8 twist barrel is matched to the .300 AAC Blackout cartridge giving shooters flexibility between subsonic and supersonic loads in a compact package well suited to short-barreled builds. The included PWS Triad muzzle device is engineered to work with the piston system to further reduce recoil and muzzle rise. Forward assist controls and a fully forged upper receiver bring the platform closer to true mil-spec dimensions and durability. Finished in a durable black anodized coating the upper is fitted with an 8.9 inch PWS PicLok M-LOK free-float handguard that keeps the barrel isolated from accessory-induced stress for more consistent accuracy. It ships complete with a Radian Raptor ambidextrous charging handle giving shooters faster more ergonomic manipulation from either side of the rifle. Designed to drop onto any compatible AR-15 lower this upper offers a straightforward path to a piston-driven .300 Blackout platform without a full rifle purchase. For shooters who want the reliability of a PWS piston system in a .300 Blackout upper the MK109 MOD 1-M is available for sale at GrabAGun. Primary Weapons Systems MK109 MOD 1-M Upper Specifications Brand: Primary Weapons Systems Model: MK109 MOD 1-M Type: Complete Upper Receiver Caliber: .300 AAC Blackout Barrel Length: 9.75 Twist Rate: 1:8 Handguard: 8.9 PWS PicLok M-LOK Muzzle Device: PWS Triad Finish: Anodized Fits: AR-15 Included: Radian Raptor Ambidextrous Charging Handle Available At: GrabAGun