Primary Weapons Systems MK111 Pro 11.85in Upper
This review covers the Primary Weapons Systems (PWS) MK111 Pro 11.85-inch piston-driven upper assembly. The reviewer highlights its slick rail, elegant design, and the benefits of a piston system, including reduced fouling and heat in the bolt carrier group. Key features discussed are the 223 Wylde chamber for accuracy and 5.56 NATO pressure handling, the three-position adjustable gas block for suppressor use, and the smooth operation of the bolt and charging handle. The upper is praised for its reliability and shootability, making it an excellent suppressor host.











