Primary Weapons Systems (PWS), based in Boise, Idaho, is known for bringing long-stroke gas-piston operation — the system used in the AK and M1 Garand — to the AR platform. This approach keeps the action cleaner and runs reliably across a wide range of conditions and barrel lengths, particularly with suppressors and short barrels.
The MK series anchors the lineup, offering piston-driven rifles and pistols in 5.56, .223 Wylde, and other chamberings, alongside the long-stroke-piston AK-pattern and straight-pull rifles the company has developed. PWS also makes well-regarded muzzle devices and components. The emphasis throughout is on durability and reliable function under hard use.
For shooters who want a piston-driven AR built to run hard, Primary Weapons Systems is a respected specialist in the category.