Rock River Arms RRAGE 3G A4 carbine upper comes chambered in 5.56mm NATO. This extruded aluminum upper receiver comes with a port door and no forward assist. Additionally, this upper is equipped with a RRA 15" RRAGE 3G M-Lok compatible handguard, a 16" chrome moly barrel, A2 flash hider, bolt carrier group and charging handle assembly. Features : .223/5.56 RRAGE 3G Complete Upper Half 16-Inch Chrome Moly Barrel, M-Lok Compatible Free Float Rail A2 Flash Hider STATE RESTRICTION NOTICE This product may be regulated as an "assault weapon" feature or component (e.g., threaded barrel, muzzle device/compensator, or assembled upper) and may be restricted or prohibited in CA, CT, DC, HI, IL, MA, MD, NJ, NY, RI, VA, WA, and select municipalities. It is the buyer's responsibility to verify local, state, and federal laws before purchase. Orders that cannot ship to a restricted address will be canceled and refunded.