Interesting and at this juncture, I'd say that the preponderance of evidence points to Canon Fanget or Fanget & Co. owning the cupped-up duck trademark stamp. Maybe additional info will shore up this hypothesis or point to the actual fella.
The following blog/thread on St. Etienne tube making just might be informative and an English translation most insightful?
http://gravure.blog.fr/2011/03/28/la-fabrication-des-canons-a-saint-etienne-suite-10904999/Kind Regards,
Raimey
rse
Interesting to note that there were 105 gunmakers still in business in St. Etienne AFTER WWII. I would've thought the number would have been significantly less by then.
Re the barrelmaking article in question, it's interesting and worth saving if you can read French. However, I would not undertake a translation just for the fun of it. Insufficient fun.