They would never use a French gun?
I think they would, as a war trophy from the recent Blitzkrieg in France. They must have plundered wagons of them. And re-proofed them to show they don't trust the French.
What I think could be suspicius with this piece is the Luftwaffe eagle on the stock, like the one on the famous pilot's drilling by Sauer.

With kind regards,
Jani