Radical Firearms MHR 5.56mm NATO 16in Black Anodized Semi Automatic Modern Sporting Rifle – 10+1 Rounds – CO Compliant – The Radical Firearms 16in 5.56mm AR rifle uses upper and lower receivers along with their rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories. Regardless if it’s your first or fiftieth, a Radical Firearms AR rifle will not disappoint! This model Is Colorado Compliant and features a 10rd mag.