I built some bag riders for the buttstock of my AR's. Picture 8 & 11 are on an A2 stock. I removed the sling mount and cut it apart and welded it to a piece of flat stock and welded a piece of a 3/4" shaft to it. Pictures 2 & 6 are on a colapsable stock it is made from a piece of flat stock welded to a 1" angle and a nut welded to the flatstock to secure it. O the colapsable stock the bag rider sits at 90 degrees where on the A2 it required a slight bend to sit paralell with the aluminium plates attached to the forearm.