Primary Weapons Systems MK111 Mod 1-M Complete Upper – 11.85″ Barrel | .223 Wylde | PWS Long-Stroke Piston System

The PWS MK111 Mod 1-M Upper is a premium, duty-ready upper receiver assembly built for shooters who demand reliability, performance, and innovation. Engineered around the versatile .223 Wylde chambering, this upper allows for precision shooting with both 5.56 NATO and .223 Remington ammunition. The 11.85″ barrel strikes a balance between maneuverability and ballistic efficiency—ideal for CQB, home defense, or SBR setups.

What sets this upper apart is PWS’s proprietary long-stroke gas piston system—mirroring AK-style durability while reducing carbon fouling in the receiver. The Mod 1-M series also features the upgraded PWS 6.9″ free-floating M-LOK handguard for enhanced modularity and a sleek profile. All housed in a robust, black anodized 7075-T6 aluminum upper receiver.

PWS MK111 Mod 1-M Complete Upper – 11.85″ Barrel | .223 Wylde | Long-Stroke Piston | AR-15

The MK1 MOD 1-M line, revamped for 2018, features the PWS long stroke piston system. Internally, this line offers the tried and true system that PWS owners have grown to know and love. Featuring a free-float MLOK handguard, forward assist controls, and a more true to mil-spec design, the MK1 MOD 1-M line is a go-to for not only civilians, but also Law Enforcement. With fully forged receivers, the MK1 MOD 1-M is a no-nonsense tool for when you need a high value option that is relentless and unstoppable.

Built for reliability and performance, the PWS MK111 Mod 1-M Upper Receiver features an 11.85″ .223 Wylde barrel, combining 5.56 NATO strength with .223 Rem accuracy. This complete upper utilizes Primary Weapons Systems’ long-stroke piston system, delivering cleaner operation and enhanced durability under hard use. The free-floating M-LOK handguard, forged upper, and Radian Raptor charging handle round out a professional-grade setup for tactical, duty, or suppressed AR builds….

Key Features of Primary Weapons Systems MK111 Mod 1-M Complete Upper – 11.85″ Barrel | .223 Wylde | PWS Long-Stroke Piston System:

• Caliber: .223 Wylde (accepts .223 Rem & 5.56 NATO)

• Barrel Length: 11.85” with 1:8 twist

• Operating System: Long-stroke gas piston – reduces recoil and heat buildup

• Handguard: 6.9″ PWS M-LOK free-floating handguard

• Material: 7075-T6 Aluminum Upper, Black Hardcoat Anodized

• Muzzle Device: PWS FSC556 compensator (factory-installed)

• BCG & Charging Handle Included: Yes – Fully assembled and ready to drop in

Why Choose the MK111 Mod 1-M:

 Whether you’re building a high-performance SBR or upgrading your current AR-15 setup, the MK111 offers battle-proven reliability, excellent gas control, and rugged craftsmanship from Primary Weapons Systems. This upper is a serious contender for law enforcement, duty use, or civilian enthusiasts wanting top-tier performance.

Ideal for: SBR builds, suppressed setups, and shooters demanding high-end performance and easy maintenance.

Also Available :

AR-15 Upper Receivers