The VK-1 rifle uses a patented low-profile piston system design featuring optimum gas port sizing and an advanced piston assembly. This features a unique cup and spigot design that improves the gas seal and overall efficiency of the gas system. The VK-1 includes a staged gas bleed system that allows the rifle to operate consistently, either suppressed or unsuppressed, with varying types of factory ammo. The VK-1 Short Stroke Piston System includes a fully-supported one-piece OP rod and removable gas block which matches the footprint and weight of a standard DI AR-15 while providing the benefits of a piston driven system.