Years back, and even more recently, there were some unscrupulous snake oil sales folks, defarbing Italian guns and passing them to
unsuspecting buyers as "originals." Some were well enough done, some folks who should have known better, fell into the trap.
Later, closer inspection proved them to be forgeries. Shootable, but forgeries none the less. Could be your FIL was caught up in
the Gun Forgery tom foolery. Wouldn't be the first, Won't be the last.
A lot to be said for a nice shootable forgery.
Coffinmaker