The Primary Weapons Systems MK111 Mod 1-M Upper Receiver brings the proven PWS long-stroke piston system to a compact AR-15 platform. Built on fully forged 7075-T651 aluminum receivers with a free-float M-LOK handguard, this 11.85" .223 Wylde upper is designed for cleaner operation, reduced fouling, and dependable accuracy with both .223 Remington and 5.56 NATO ammunition. The included compensator and Radian Raptor ambidextrous charging handle round out a well-thought-out package focused on reliability and smooth handling.

This complete upper is ideal for shooters who want a short, suppressor-ready setup for range use, training, and general-purpose duty where controllability and consistency matter. The adjustable gas regulator lets you tune the system for unsuppressed or suppressed shooting, while the ergonomic M-LOK handguard offers ample space for lights, grips, and other accessories. With its sub-MOA accuracy potential and refined piston-driven design, the MK111 Mod 1-M reflects Primary Weapons Systems’ reputation for practical innovation and meticulous craftsmanship.

• Manufacturer: Primary Weapons Systems
• Model: MK111 Mod 1-M Upper, MK1-M1U-223-11
• Caliber: .223 Wylde (Accepts .223 Remington And 5.56 NATO)
• Barrel Length: 11.85"
• Action: Semi-Auto, PWS Long-Stroke Piston System
• Twist Rate: 1:8
• Handguard: Free-Float M-LOK