The SR-25 (Stoner Rifle-25) is a semi-automatic sniper rifle designed by Eugene Stoner and manufactured by Knight's Armament. The SR-25 uses a rotating bolt and a direct impingement gas system. It shares some parts with 5.56x45mm AR-15 platforms, mostly in the trigger group, with the rest of the rifle largely requiring unique parts to support a larger cartridge. The SR-25 is chambered for the 7.62x51mm NATO cartridge