Primary Weapon Systems

Overview

The Primary Weapons Systems MK114 Mod 1-M is a complete upper receiver designed for AR-15 platforms, featuring a 14.5-inch barrel chambered in .223 Wylde, which allows for optimal performance with both .223 Remington and 5.56 NATO ammunition. Its mid-length gas system provides a smoother cycling operation and reduced recoil, while the 1:8 twist rate ensures improved stability for a wide range of bullet weights. This upper is particularly popular in builds that benefit from a mid-length gas system and the versatility of .223 Wylde caliber.