The top of the shotgun barrels is engraved “Carl Lobbenberg” and “Altona”

I assume Carl was either the maker or the retailer but I wasn’t able to find much information about him aside from references to straight edge razors w his name. I assume Altona is the town in Germany where it was either sold or made?

Also, I am curious about the date of manufacture- any chance the numbers stamped on the side of the rifle bbl in the picture are a date code? “1/24” could that be for January 1924? Below that is “42”, could that be for 1942?

Thank you all for any additional information!