Primary Weapons Systems MK1 MOD 1-M Complete Upper Features The Primary Weapons Systems MK1 MOD 1-M Upper is built around the PWS long stroke piston system a design that keeps the action running cleaner than a direct impingement gas system by venting propellant gas and fouling away from the receiver rather than dumping it straight into the bolt carrier group. A 3 setting adjustable gas regulator lets shooters tune the system for different ammunition or suppressor use improving reliability across a range of conditions and reducing the felt recoil and bolt velocity swings that come with unregulated piston guns. The 16.1 inch threaded barrel has a 1:8 twist rate for stabilizing 7.62 X 39 projectiles giving the platform the reach and consistency this cartridge needs from a carbine-length gun. The PWS Triad30 muzzle device helps manage recoil and muzzle rise keeping the sight picture settled for faster follow up shots while the forged T6 7075 upper receiver is hard anodized in black for corrosion resistance and a durable mil-spec style appearance that holds up to hard use in the field or on duty. A Radian Raptor ambidextrous charging handle gives shooters fast positive manipulation of the bolt carrier group from either side of the rifle a real advantage for left-handed shooters and anyone running the gun with a suppressor where extra leverage to break the bolt free matters. The free-float M-LOK handguard allows for the attachment of lights grips and other accessories without contacting the barrel helping preserve accuracy by keeping pressure off the barrel itself under sustained fire. Forward assist controls and a more true to mil-spec design round out this revamped 2018 line making it a dependable choice for both civilian shooters and law enforcement use who want a piston gun that still accepts standard AR furniture and parts. Whether building a new rifle around this upper or dropping it onto an existing lower to add a piston-driven 7.62 X 39 option this upper delivers a reliable high value platform backed by a manufacturer known for pushing piston AR design forward. Primary Weapons Systems MK1 MOD 1-M Complete Upper Specifications Manufacturer: Primary Weapons Systems Model: MK1 MOD 1-M Complete Upper Caliber: 7.62 X 39 Barrel Length: 16.1 Color: Black Finish: Anodized Operating System: PWS Long Stroke Piston 3 Setting Adjustable Gas Regulator Gas System Length: Mid-Length Twist Rate: 1:8 Muzzle Device: PWS Triad30 Charging Handle: Radian Raptor Ambidextrous Handguard: PWS M-LOK 15.05 Compatible Hosts: AR-15 Available At: GrabAGun