Guns PWS – Modern Musket. We echo these sentiments. Recoil Staff June 3, 2014 0 COMMENT Well spoken! Questioned about the DI move when their piston guns (Mk 1 and Mk 2) are so popular, PWS replies, “…there’s still a lot of folks that don’t know user/maintenance friendly piston is…or just prefer DI regardless. We watn them to be PWS owners too…” Primary Weapon Systems has teamed up with Modern Musket to release a line of direct impingement rifles. They will be shipping to dealers later this month – we’ll provide additional details as soon as we have them.