I have had a number of Stith mounts over the years and Stith seemed to have a thing for hex screws. He used them to create composite parts which another manufacturer would have made one piece. This is particularly true of the front mounts which make use of the dovetail slot in the barrel created for the rear sight.
Most Stith mounts are fastened to the receiver using the factory drill and tapped holes for receiver sights and are held on with the same sort of ordinary screws used by those sights. I would ignore the hex screws and simply remove the slotted screws, if any.
