Uncle Mike's has a set just made for that -
It has a short threaded stud that screws into a pre-tapped hole in your magazine cap. At least the ones that I have were pre-tapped. IIRC it is a NF (fine) thread. If the cap isn't tapped, it can be drilled and tapped for one.
The rear stud is has a regular wood screw thread.
Makes for a really neat looking installation.
How many peckers can a Pecker Checker check if a Pecker Checker could check peckers?
(stolen from shootinurse)