The PWS MK114 MOD 1-M complete upper is a .223 Wylde AR-15 upper with a 14.5-inch barrel, an M-LOK handguard and a long-stroke piston operating system, supplied with no compensator installed (PWS part no. MK1M1U22314NC). The .223 Wylde chamber runs both .223 Remington and 5.56 NATO ammunition, and the 1:8 twist suits the common bullet weights in both. Because Primary Weapons Systems builds the MK1 line around a piston, hot gas and carbon stay out of the receiver and bolt carrier, which keeps the action cleaner over a long day at the range. It ships as an upper only, ready to mate to a compatible AR-15 lower, and leaves the muzzle bare for the builder’s choice of device.

Key Specifications

• The upper is chambered in .223 Wylde, so it can fire both .223 Remington and 5.56 NATO ammunition.
• Barrel length is 14.5 inches, a common length for a full-power carbine-style upper.
• The twist rate is 1:8, matched to the common .223 and 5.56 bullet weights.
• It runs a long-stroke piston with an adjustable gas regulator rather than direct impingement.
• The piston design keeps hot gas and carbon out of the receiver, which keeps the bolt carrier cleaner.
• The handguard is an M-LOK design, so accessories mount directly to the rail.
• It is the no compensator version, so the muzzle is bare for a device of the builder’s choice.
• The receiver is forged 7075-T651 aluminum, anodized for corrosion resistance.
• It is supplied as a complete upper, with the barrel and operating system installed.
• It ships as an upper receiver group only, so a compatible AR-15 lower is needed to complete the rifle.
• PWS’s pinned MK114 carries the same 14.5-inch barrel pinned and welded to 16 inches overall with its compensator; this no-compensator version does not, so measure your finished rifle’s overall length.

Frequently Asked Questions

Does this upper include a lower receiver? No. It is an upper receiver group only and needs a compatible AR-15 lower to complete the rifle.

Does it come with a compensator or flash hider? No. This is the no compensator version, so the muzzle has no device installed.

What operating system does it use? It uses PWS’s long-stroke piston system rather than a direct-impingement gas system.

Buy the PWS MK114 MOD 1-M Complete Upper, .223 Wylde, 14.5-Inch, No Compensator

Order it from our Lubbock, Texas gun shop for fast, direct shipping, and browse our AR-15 uppers for more complete uppers.