The FN SCAR (Special Operations Forces Combat Assault Rifle)[9] is a gas-operated (short-stroke gas piston)[8] self-loading rifle with a rotating bolt.[10] It is constructed to be extremely modular, including barrel change to switch between calibers. The rifle was developed by FN Herstal (FNH) for the United States Special Operations Command (SOCOM) to satisfy the requirements of the SCAR competition