Sorry Carcano. I assumed 'Manufactur' was a shortened version of 'Manufacturière'
I believe your hypothesis would explain the odd font of the 577 EXPRESS. The other proof marks certainly appear genuine however.

Or maybe not. A 1926 by lettre annale .475 No. 2 with similar EXPRESS font

[Linked Image from photos.smugmug.com]

Last edited by Drew Hause; 12/06/25 06:34 PM. Reason: More information