Yeah, Otto was quite the double gunsmith...the patent below is for a double single trigger...the guys he was friends with say that he made the patent gun from scratch, rather than fit his mechanism to an already existing gun, but I've never seen any guns marked Neubrand...Although I had been to his shop in Clarence NY many times,back then, I didn't know enough about doubles to ask to see it (or any other guns that he made from scratch) ...