Made in Belgium, today!
This caliber 16 has come to light today. It seems work of the Belgian gunsmith Jules Gervais who had his store in Antwerp and owned the name La Parfaite ( The Perfect One) he registrated in 1904.
The two FNcases seem to be enormous blanks at first sight. I doubt they are! Never seen this structure before. Is there someone out who knows something more about them?