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.Includes magpul gen3 pmags, rifle lock and hard case.Caliber: 5.56mmBarrel Length: 13.70"Capacity: 30+1Trigger: Hiperfire Single StageOal: 30.50"-33.10"Weight: 6.60 lbsStock Description: Magpul SLMuzzle: HUXWRX Flash Hider QD XL Pinned/WeldedReceiver Material: SteelSights: None, Optic ReadyBarrel Description: Steel ThreadedTwist: 1:7"Barrel Length Range: 13" to 13.99"Weight Range: 6 lbs to 6.99 lbsHand: AmbidextrousStock Finish Group: Black