I would suggest posting this request on the German gun subforum here as well. Take the barrels off and take pictures of the stamps on the portion of the barrels that contact the action, and also of the stamps on the action. You should also check if there are any stamps on the lumps (the extensions on the barrels that slide into the slots in the action).

Nice scroll engraving on the sxs - I wished that design was found on more Merkels.

Such a long, long time to be gone, and a short time to be there.