Use Mesa Tactical's collapsible stock kits and adapters to install AR-15 adjustable buttstocks and pistol grips onto the venerable Mossberg 500 shotgun platforms for the ultimate in tactical shotgun configuration performance. The concept behind the telescoping stock system is simple: the shotgun stock is replaced by an adapter, which attaches to the rear end of the shotgun's receiver and it, in turn, mimics the rear end of an AR-15 lower receiver, into which an AR-15 receiver extension tube can be threaded. The AR-15 telescoping stock and pistol grip can then be reliably attached.