Semi auto & ejecting except for the last case with you use the manual ejector to dump out.
BBl moves forward upon firing to rotate the cylinder. Excess gas pressure from betw the chamber sleeve and the breech ejects the prior fired shell from the open port. That's why the last one has to be manualy ejected.
Standard (at the time) short chambered 16ga shotshell.
These were made by Deutsch Jagdwaffen gesellschaft in Dusseldorf (sp?)
That mfg'r name and some details about the operation of it I'm recalling from an article about these in the German Gun Collectors Assn publication newsletter a while back. So I might be a bit off in some details.
I believe the GGCA was trying to buy a specimen in nice condition from an American collector that had been liberated during WW2. They wanted to repatriate (correct word?) the shotgun back to a museum in Germany.
One of about 100 made so says most of the posted info on these,,I'd say that was quite a find for a vintage arms/shotgun collector!
The lamp attachments can be gone with a good restoration effort.
Very nice day at the flea market.