The FN USA FN15/AR upper receiver assemblies are engineered to fulfill the rigorous requirements of law enforcement, military personnel, competitive shooters and sports enthusiasts. These complete upper assemblies are meticulously designed to address user-specific needs. Stringent quality and compliance standards are adhered to, ensuring that the highest levels of engineering and craftsmanship are applied during production and testing. This guarantees consistent and optimal performance. FN 15 16 inches carbine upper assembly Barrel profile - M4 configuration Carbine length gas system A2 front sight post assembly Two-piece, single heat shield, oval handguard Cold hammer forged process CrMoV barrel steel (proprietary) Hard chrome-lined in compliance with military standard 171 M4 feed ramps Pressure tested at high levels Magnetic Particle Inspection (MPI) Manganese phosphate coating