The oddest one I recall was a made-in-India derringer...in .303 British. I kid you not. It came into a local gunshop with a grab-bag of assorted stuff from Europe. We actually chambered a round (to see if it actually fit), and it did. Considering that it: a) appeared to be made of hand-pounded railroad track (although the finish was surprisingly good), and; b) there was basically no barrel - just the chamber, and enough barrel that only half of the bullet was actually inside the gun, none of us had the intestinal fortitude to try firing the thing. I recall comments about hand grenades, etc. I should have bought it at the time, just as a curiosity. IIRC, it sold for $20.