I just got a thing. It was most likely made around 1925 (this one was made in ‘26 and is only 1,000 different in serial number). 16GA, and the barrel recoils as part of the action, which is fawrking awrsome.
The Auto 5 was the first mass-produced semi-auto shotgun. It was made by FN Herstal in Belgium for Browning for sale in the US up until WWII - most of the older ones are 16GA - and was also made as a Remington.
Pictures-wise, it looks pretty much exactly like that one as well, other than still having the original furniture, which has a rounded grip like this:
PEW PEW PEW PEW PEW *click*