Primary Weapons Systems MK114 Mod 1-M Complete Upper Features The Primary Weapons Systems MK114 Mod 1-M is built around a long stroke piston operating system with a three setting adjustable gas regulator letting the shooter fine-tune cycling to match ammunition suppressor use or environmental conditions. This piston design keeps combustion gases out of the receiver reducing the fouling and heat buildup that traditional direct impingement systems push back into the action. Chambered in .223 Wylde the upper safely runs both .223 Remington and 5.56 NATO ammunition giving the shooter flexibility in ammunition selection without sacrificing chamber tolerances built for accuracy. The 14.5 inch barrel pairs with a 1:8 twist rate and a mid-length gas system producing a muzzle velocity around 2921 fps for dependable terminal performance at middle distances. The upper receiver itself is forged from 7075-T651 aluminum and finished with a hard coat anodized coating per Mil-8625 Type III Class 2 standards giving it strong resistance to wear and corrosion over years of use. A free-float M-LOK handguard measuring 13.624 inches long 1.7 inches wide and 2.25 inches tall provides ample real estate for lights grips and other accessories while keeping the barrel free of contact-induced stress. An ambidextrous Radian Raptor charging handle improves manipulation speed for shooters of either hand a detail appreciated by both civilian owners and law enforcement users. Revamped for modern use while keeping forward assist controls and a more true to mil-spec design this upper ships with no muzzle device installed leaving NFA considerations to the end user and the Primary Weapons Systems MK114 Mod 1-M Complete Upper is available for sale at GrabAGun. Primary Weapons Systems MK114 Mod 1-M Complete Upper Specifications Manufacturer: Primary Weapons Systems Model: MK114 Mod 1-M Complete Upper Caliber: .223 Wylde Barrel Length: 14.5 Twist Rate: 1:8 Gas System Length: Mid-Length Operating System: PWS Long Stroke Piston 3-Setting Adjustable Gas Regulator Color: Black Finish: Anodized Receiver Material: 7075-T651 Aluminum Handguard: M-LOK 13.624 Charging Handle: Radian Raptor Ambidextrous Muzzle Velocity: 2921 fps Compatible Hosts: AR-15 Weight: 4.6 lbs Available At: GrabAGun