Really like the 5mm Remington Mag. Remington abandoned it long ago. Aquila made some under the name Centurion but most of that has been sold from what I can tell. Some on Gunbroker though, good luck with the search. As hard as it is to find ammo these days I am hanging onto what I have to be fed to my litte abandoned Remington.
I owned one for 15 minutes. I bought it at a gunshow for $125 with two boxes of ammo (mid '80's). I was walking back to our table and was ask how much I wanted for it I say $200, we agree on $175. It is a good cartridge just no ammo today.