FN SCAR 17S 13" Barrel Assembly. The FN SCAR barrel assemblies are cold hammer-forged steel barrels with front sight assembly, gas block assembly, gas regulator, gas piston and flash hider installed. Available in short lengths for reduced weight, fast handling and confined space maneuvering. Assemblies can be easily installed by the user with a torque wrench and are ready to shoot without headspacing. This barrel will only fit FN SCAR 17 rifles chambered in 7.62 NATO.