The only other Gardone V.T. maker I know that even remotely looked like the Beretta back-actions were the Gamba shotguns (Flli Gamba, or post-'67 Renato Gamba) that would be marked as San Marco or S. Marco.
I can't see clearly on your picture that shows the city marking. Does it have S. Marco on the line or two above Gardone?
It is really hard to read it is double stamped, but it is san something, and above that is armeria, over to the right there is a 1.
Wher the shield with armeria and SG is, there is a RAM, or PAM, or it could be BAM