I am not sure if not some schrader action guns were made before dreyse bought the right to make it. I have seen at least one schrader gun with no dreyse markings. in his 1899 book about hunting guns georg koch, who was the uncle of the firm owner Nikolaus v. Dreyse( the grandson), is mention the schrader action especially so this was probably the time when the firm was in talks with schrader about his patent.