I had to make one in a hurry so I just took a 5/16" hex head screw and ground the head down to ABOUT .075" thick. Then file/grind 2 opposing sides so they're a slip fit into under 1/2" wide. I think mine are .480" so it's an easy slide. Do you want it for a hand stop on a target rifle or is it to mount a bi pod? Mine was for a hand stop so I just drilled/tapped a piece of delrin 5/16" and could then screw it into the rail and lock it as a handstop.