The manual says not to use the existing stud hole (they were made by Hogue and turned into the Knoxx stock) because the stud will interfere with the recoil reducing mechanism. It says to drill another hole 1.25" up from the existing hole. First of all, how deep do you go? What size bit? And finally, what stud will screw into it and be secure? It looks like plastic to me. Anybody else do it?