Primary Weapons System PWS Complete 5.56mm MK-112 Upper

The MK1 series, developed by Primary Weapons Systems, is a significant product improvement for the M4/M16-type carbines and rifles. Utilizing our proven long stroke piston system, the MK1 series greatly reduces fouling in the action of the weapon making it as reliable as the AK47 that it was designed after.
The MK1 series has been used in Iraq and Afghanistan, and has gained wide popularity with security personnel, law enforcement and civilians alike.
The origins of the MK1 series began with the fascination in the simplicity and reliability of the AK47 combined with a deep-rooted appreciation for the ergonomics of the M4/M16 platform. Having a significant understanding of the deficiencies in the direct gas impingement operating system found on conventional M4/M16-style weapons, PWS developed the MK1 series with the professional in mind.
Significant improvements have been made over both the direct gas impingement operating system and previous offerings of piston-driven operating systems. The product improvements made by PWS have addressed reliability and performance issues as well as reduced carrier tilt, cam pin wear and carrier bounce. In addition, we have one of the lightest systems on the market today!
An innovative hand guard system utilizes a proprietary non-free float system that allows the end user or unit armorer to replace individual rails as needed without removing the barrel, barrel nut or even other rails. This system allows the user to attach numerous Picatinny rail-mounted devices such as sights, lights, and laser aiming devices.
The PWS proprietary operating system utilizes an operating rod that is attached to the carrier and a floating head piston that is attached to the operating rod. The MK1 series is built to be a true combat carbine. With no unnecessary gas adjustments and only one moving assembly, this is the most rugged, simple and versatile piston operating system available.
The MK1 series is available as a complete rifle or as a complete upper receiver for use on existing M4/M16 style lower receivers.
5.56 NATO
4 lbs 4 oz (1.92 kg)
Overall Length
21.4" (54 cm)
Barrel Length
12.5" (31.75 cm)
Barrel Specs
Stainless Steel, Isonite™ Treated, Button Rifled, 1:8 Twist Barrel
Muzzle Velocity
2799 ft/sec (SS109)
Muzzle Energy   1076 ft/lbs
Stainless Steel, Isonite™ Treated, Button Rifled, 1:8 Twist Barrel
Enhanced Charging Handle
Mil Spec Upper Receiver
PWS Enhanced Bolt Carrier Group
Isonite™ Treated Internals
PWS Triad 556 comp

**All NFA Rules Apply to AR Rifle Lowers** Know your State and Local Laws regarding this upper before purchase. This is considered a SBR if mounted to a Rifle Lower Receiver

Primary Weapons System PWS Complete 5.56mm MK-112 Upper
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  • Item #: PWS-MK112
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Price $1,449.95
Availability Backorder Allowed
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