
Availability: In Stock
Current Stock: Out of stock
The Primary Weapons Systems MK1 Mod 2-M upper receiver in .223 Wylde with an 11.85-inch long-stroke piston system is built for shooters who demand reliability and precision in an AR-pattern rifle. This 223 Wylde upper chambers both .223 Remington and 5.56 NATO ammunition, giving you flexibility at the range or in the field. The long-stroke piston design is the backbone of PWS's reputation—it cycles reliably under diverse conditions while keeping fouling to a minimum, which means longer periods between cleanings and more time actually shooting.
The three-position adjustable gas block is the key to this upper's versatility. Fine-tune gas flow to match your ammunition type, shooting environment, or suppressor setup. Running it unsuppressed? Crank it for reliable cycling. Running a can? Dial it back to reduce backpressure, lower gas blowback, and get a cleaner shooting experience without sacrificing function. That flexibility is what separates a good upper from one that actually adapts to how you shoot.
The FSC 556 muzzle brake addresses what matters in the real world: recoil and muzzle rise. Better control means faster follow-up shots and less fatigue over a long session. The PicLok handguard integrates both Picatinny rail and M-LOK slots, so you're not locked into one mounting standard—mount lights, lasers, grips, or whatever else you need without rail adapters. The included Radian Raptor ambidextrous charging handle works equally well for lefties and righties, no compromises.
Accuracy matters, and PWS delivers with precision barrels that will hold sub-MOA groups when you do your part. This is an upper built to shoot, not just sit on a shelf.
| Brand | Primary Weapons Systems |
| Model | MK1 Mod 2-M |
| Chambering | .223 Wylde |
| Barrel Length | 11.85 inches |
| System Type | Long-stroke piston |
| Gas Block | 3-position adjustable |
| Muzzle Device | PWS FSC 556 |
| Handguard | PicLok (Picatinny and M-LOK) |
| Charging Handle | Radian Raptor ambidextrous |
| Product Type | Upper receiver assembly |
The .223 Wylde chambering is compatible with both .223 Remington and 5.56 NATO ammunition, giving you flexibility to use either cartridge without concern.
Yes. The three-position adjustable gas block allows you to tune the upper specifically for suppressor use, reducing backpressure and gas blowback for a cleaner, more comfortable shooting experience while maintaining reliable function.
Yes, the Radian Raptor charging handle included with this upper is fully ambidextrous, so both left and right-handed shooters can operate it smoothly and naturally.
The PicLok handguard integrates both Picatinny rail and M-LOK slots, allowing you to mount accessories using either standard and giving you flexibility in how you configure your setup.

SKU: 152744482 • Weight: 4.5oz


Availability: In Stock
Current Stock: Out of stock
The Primary Weapons Systems MK1 Mod 2-M upper receiver in .223 Wylde with an 11.85-inch long-stroke piston system is built for shooters who demand reliability and precision in an AR-pattern rifle. This 223 Wylde upper chambers both .223 Remington and 5.56 NATO ammunition, giving you flexibility at the range or in the field. The long-stroke piston design is the backbone of PWS's reputation—it cycles reliably under diverse conditions while keeping fouling to a minimum, which means longer periods between cleanings and more time actually shooting.
The three-position adjustable gas block is the key to this upper's versatility. Fine-tune gas flow to match your ammunition type, shooting environment, or suppressor setup. Running it unsuppressed? Crank it for reliable cycling. Running a can? Dial it back to reduce backpressure, lower gas blowback, and get a cleaner shooting experience without sacrificing function. That flexibility is what separates a good upper from one that actually adapts to how you shoot.
The FSC 556 muzzle brake addresses what matters in the real world: recoil and muzzle rise. Better control means faster follow-up shots and less fatigue over a long session. The PicLok handguard integrates both Picatinny rail and M-LOK slots, so you're not locked into one mounting standard—mount lights, lasers, grips, or whatever else you need without rail adapters. The included Radian Raptor ambidextrous charging handle works equally well for lefties and righties, no compromises.
Accuracy matters, and PWS delivers with precision barrels that will hold sub-MOA groups when you do your part. This is an upper built to shoot, not just sit on a shelf.
| Brand | Primary Weapons Systems |
| Model | MK1 Mod 2-M |
| Chambering | .223 Wylde |
| Barrel Length | 11.85 inches |
| System Type | Long-stroke piston |
| Gas Block | 3-position adjustable |
| Muzzle Device | PWS FSC 556 |
| Handguard | PicLok (Picatinny and M-LOK) |
| Charging Handle | Radian Raptor ambidextrous |
| Product Type | Upper receiver assembly |
The .223 Wylde chambering is compatible with both .223 Remington and 5.56 NATO ammunition, giving you flexibility to use either cartridge without concern.
Yes. The three-position adjustable gas block allows you to tune the upper specifically for suppressor use, reducing backpressure and gas blowback for a cleaner, more comfortable shooting experience while maintaining reliable function.
Yes, the Radian Raptor charging handle included with this upper is fully ambidextrous, so both left and right-handed shooters can operate it smoothly and naturally.
The PicLok handguard integrates both Picatinny rail and M-LOK slots, allowing you to mount accessories using either standard and giving you flexibility in how you configure your setup.
SKU: 152744482 • Weight: 4.5oz
