The following advertisement was found in the 1905 edition of Deutsche Jagd und Deutsche Fürsten by fritz Frenzel
The following images of a Collath gun that is a two barrel set are courtesy of Mr. Fredrik Franzén in Sweden.
Following are more images from Fredrik Franzen of a W. Collath double rifle with a Clam Shell (Mussellverschluss) action.
The following images are courtesy-
