Janisson, 26 cours Fauriel, St-Etienne.
Was in business in 1951. I don't have any other info.
"Jeune" means "the younger", e.g. one of his predecessor was in the business too.
Cours Fauriel was one of the hotspot of the gun making industry in St-Etienne.
Seems like a St Etienne industry standard Helice gun.

WC-