I've got a nice custom Martini action .22, which is a takedown. The gun was already partially customized when I got it, but I had a lot more work done. Greener commercial action, had a screw, not a pin, as the action release when I got it (now has a screw with a lever, allowing finger takedown). Splits on the bottom of the receiver front and the barrel turns out. What model was this likely to have been originally?