http://www.rockislandauction.com/viewitem/aid/1027/lid/2755

The most popular shotgun made by the French Darne company was their 1897 sliding breech side-by-side, which saw sales and use worldwide. Before that, however, Darne invented a rotating breechblock system - first a series of external hammer varieties in the 1880s and then this hammerless Model 1892. It is a great example of a functional, creative, and interesting system that simply never became popular.