My behind-the-door gun:
1943 USGI Underwood receiver, Inland barrel, modern folding stock, Ultimak clamp-on style rail, Leupold reflex red-dot. Leather sling is a Stolla Wein Bavarian from the 50s lend-lease program.
Bought it from the CMP "back when" and the stock and hand guard were shriveled up and dry. I carefully sealed them up in a vacuum bag for future work and re-homed the metalwork into something interesting.