You know as much as I do at this point, I got sent the pics above, as they had no idea what it was and a mutual friend figured I’d know.
I may have shot myself in the foot, as I told them it’s obsolete cal, wall hanger so they might not want to part with it. I should of scared them into surrendering it to a LAFO (me) lol!
Bummer
So far my enquiries have been met with silence. 
If it’s rare like you say they might be doing some research and price shopping first.