Thanks all, appreciate the help. 20.3 seems like it would make sense for a chamber diameter--seems the most plausible thing I can think of, anyway. I do have a photo of the inside of the fore end (for some reason that portion of the image was cropped when I posted it), the last 4 digits of the serial number are there but definitely no model number. I've requested a picture of the water table and barrel flats so hopefully that will get a definitive date and perhaps even a model.
For what it's worth I stumbled into a Beretta SxS-focused newsletter that indicated the Italian proof markings went from mm bore and choke markings to a "star" system in 1962, which if that's accurate would indicate this was a pre-62 gun. It seems to be a 40x Silverhawk, likely a 409 as Dave mentioned above, I'm just not sure how to tell the ultimate grade if the model isn't marked on it...my 1960's Beretta O/U's have significant variation in appearance and embellishment even within a given grade so I'm not sure how to be certain.
Last edited by David Furman; 03/24/15 10:37 AM.
