According to Suhl traditions (Ernst G. Dieter: Im Zeichen ds Waffenschmieds, Teil 2, Erfindungen, Patente, Konstruktionen, Kursioritäten) the design of the "clamshell" action, in Germany variously named "Stabil-", "Ideal-" or "Muschelverschluss", is ascribed to E.Schmidt & Habermann, about 1910. The unsung E.Schmidt & Habermann company, Roschstr.1, Suhl, was founded in 1858 and existed til 1945 as one of the larger Suhl gunmakers. The name is little known now, as they were predominantly gunmakers to the trade, making guns not only for wholesalers like Geco and Akah, but also for obscure "country gunshops" and famous "name" gunmakers like Barella, the Kettners, Geyger, J.J. Reeb, Miller & Greiss, J. Peterlongo and you name them. All the famous pre-war "Original Wilhelm Brenneke, Leipzig" bolt action rifles not only bear their ESHA trademark hidden somewhere, but bear ESHA serial numbers, not Brenneke's. Of course they made the guns for the "Name" gunmakers to designs and "house style" of those "makers". Other "name" Suhl gunmakers like Bernhard Merkel (not Gebr.!) F.W.Kessler (a gunmaker to the trade too) and Greifelt also made clamshell actioned double rifles, but most likely they bought in at least the rough parts, if not guns in the white or even the complete guns from ESHA. No DRP patent or DRGM design protection for the clamshell action is known. Alas, it is merely an evolution of the early pinfire doubles with trough-shaped action bars. Some of those actions even had the action bar to standing breech angle reinforced by a web, not yet as pronounced as on the clamshell action, but clearly forerunners.