Argo,
Wonderful history. Very sad that Blanchon died in 1914. Fransisque Darne, who held several unique patents related to civilian firearms, and modifications to sliding breech designs, died in 1917. There was a patent photo floating around the 'net of a sliding breech gun with removable sidelocks and more conventional hammers and springs, as opposed to strikers, with patent assignment to Francisque Darne. I have not seen evidence that this design was ever produced.
It would appear that both men were lost to history in the prime of their lives, and, no doubt left French firearms design and production the poorer for it.


Best,

Ted