"The FN USA FN15 Military Collector M4 Semi-Auto Rifle is a civilian-legal reproduction on the US Military's M4. Built to legit mil-spec standards and featuring the Knight's Armament RAS adapter rail, this is a straight-to-business, beast of a rifle. The Military Collector M4 has a 14.7"", button-broached, chrome-lined barrel that meets the 16"", legally-required length due the pinned (permanently affixed) A2 flash hider. The flat top receiver on the M4 is ready for an optic and comes with a flip-up rear sight. The carbine-length gas system features an A2 front-sight gas block. The FN USA Military Collector's KAC rail is also topped off with a KAC rail panel kit and KAC foregrip. A 6-position collapsible stock and ambidextrous safety selector allow for proper length of pull and easy controls when shoulder transitions are in play. If you're looking for a truly battle-proven setup with throw-back vibes that will have zero issues keeping up with modern rifles, the FN 15 Military Collector M4 is your guy. 14.7"" barrel with pinned A2 FH 1:7 twist KAC RAS adapter rail KAC rail panel covers and forgrip Flat-top upper receiver Rear flip-up sight A2 front sight gas block 6-position collapsible stock Ambi safety selector A2 pistol grip"