Pierre Martin.
Back in the 19th century not only a famous steel industrialist, but also a producer of Chassepot rifle barrels. The town of Sireuil was strongly connected to his achievements and his foundry.

That said, my conjecture might still be wrong. Geco often sold cheaply and probably bought raw materials even cheaper, so one could of course suspect some loud-mouthed advertising. -- Only that in Germany, barrel steels ALWAYS were associated with a name, and NEVER with abstract praises, like in so many French barrel inscriptions.

Regards,
Carcano