I have a couple of old damascus shotguns that I use (also German. lol).

Before I fired any of mine from the shoulder I did my own little proofing b y loading up the hottest loads possible in the brass shells I need to use and fired them remotely from a distance.

My 1880s 16ga Double from Uslar is now my regular quail gun.

Also, you should probably also only use black powder loads in them. I do know you're never supposed to use modern smokeless.