The St. Etienne triple proofmark first appeared in 1901 and is still in use, so that won't help you much.

Canon de surete doesn't help either. Not actually a proofmark and seen on a lot of French guns. Canon JB means that the barrels were made by Jean Breuil, a very well-known barrel maker. But that doesn't help much with a date either.

The French are pretty much unique among European gun making countries in not using a date code of some sort.