It all starts with an AR15 upper receiver, either completely stripped down or fully completed. Upper components kits, which contain the forward assist and dust cover assembly, must be purchased in addition to a stripped upper receiver. An assembled upper receiver will already have these parts attached. When talking about the AR-15/M-16 family of rifles, the upper and lower receivers are just the two sides of a receiver. The firing mechanism and magazine are located in the lower portion of a firearm with a two-piece design, while the upper houses the barrel and the bolt. By simply swapping out the upper receiver, the AR-15 may be converted from a long-range precision rifle to a CQB carbine.
