Major AR shooters need the top. They'll also will need several different add-ons attached for their weapon. These add-ons must be easy to attach and freely available for use as necessary. Over time the Maritime Corps did approve the usage of the six-placement collapsing stock on M16s for lesser shooters https://louisqcmvc.blogpostie.com/51697987/a-secret-weapon-for-knights-armament-rail