According to my ad hoc research this "Kunna Koblenz" is in fact a Franz Sodia made in 1952 (or 1951) and sold to W. Kunna of Koblenz for the German market:

https://www.gunsinternational.com/g...x57jr-16ga-24-quot-.cfm?gun_id=101224994

It should look similar to the subject 1953 proved specimen retailed by Bock.

Cheers,
Jani