The Primary Weapons Systems MK109 MOD 1 upper receiver in 300 Blackout combines PWS's proven long-stroke piston system with practical suppressor-ready dimensions that work reliably across a wide range of ammunition loads. Built on a fully forged upper and fitted with a 9.75" barrel, the TRIAD30 muzzle device, and M-LOK free-float handguard, this is a no-compromise AR platform built for shooters who demand reliability without complications. Whether you're running subsonic loads through a silencer or standard-velocity rounds unsuppressed, the piston system and barrel twist rate eliminate the need for adjustable gas tuning—it cycles as shipped.
The MK109 MOD 1 appeals to both civilian shooters and professional users who value a modular, mil-spec-inspired platform. The included Radian Raptor charging handle adds ergonomic control, while the M-LOK slots give you full flexibility to mount lights, barricade stops, or other gear without rail clutter. The 300 Blackout cartridge excels in compact rifles where its subsonic performance, power, and suppressor-friendly ballistics shine—making this upper a natural fit for short-range hunting, dynamic drills, or home defense setups.
PWS long-stroke piston guns earn loyalty through durability and track record. This upper receiver carries that reputation into a compact 300 BLK package that performs with or without a suppressor mounted. It's the kind of tool that works as advertised and doesn't ask for tweaking.
| Caliber | 300 Blackout |
| Barrel Length | 9.75" |
| Barrel Twist Rate | 1:6 |
| Piston System | Long-stroke |
| Handguard | Free-float M-LOK |
| Muzzle Device | TRIAD30 Compensator |
| Upper Type | Fully forged |
| Included Accessories | Radian Raptor charging handle |
No. The 9.75" barrel length and piston system are tuned to cycle reliably with or without a suppressor attached, without requiring an adjustable gas system.
The barrel has a 1:6 twist rate. PWS specs this upper to function reliably across a range of 300 Blackout loads—both subsonic and standard-velocity rounds perform without tuning adjustments.
The MK109 MOD 1 includes a Radian Raptor charging handle and a TRIAD30 compensator/muzzle device.
Yes. The free-float M-LOK handguard accepts standard M-LOK mounted accessories such as lights, vertical grips, and rail sections.
Primary Weapons Systems
Primary Weapons Systems
