I wonder just how old that thing really is? I have the Rifleman from 1936 to the present date, and I don't remember seeing anything about it. I have a ton of reloading to do, but if I get time, I'll look through some of the fifties copies. I'm pretty sure it wasn't in the sixties magazines. What you might do is take a regular picture and send it to the NRA and see if they remember. Sure don't look like yours ever rode on a bumper.
Paul B.