This weird looking pistol has just appeared on eGun (https://www.egun.de/market/item.php?id=11599202)
I have never come across one like it before. The seller seems to think that an inner barrel might be missing, but says that the spring unit inside can be cocked and fired. Has anyone any idea what it is or how it is supposed to work? My best guess is that it might not be an air gun but was meant to shoot darts. It could have been loaded by pressing a dart in from the muzzle.