I am very familiar with these fine guns and their variations. I am going to suggest an Italian hunting/shooting website to you. https://www.ilbraccoitaliano.net
This is a website/board hosted by some Italian shooters with interest similar to ours. More a general hunting board than a Fine gun venue, there are forums devoted to some specialty fields. One of which is a Franchi thread, and while it contains mostly information on myriad autoloader and O/U versions made by the prolific Franchi firm, there are discussions of the various SxS guns made by the company. There are in particular two VERY knowledgeable gentlemen contributors to the thread with extensive knowledge of the guns and their history. The thread has a wealth of knowledge regarding these pieces and their storied past continuing up to the present time under Beretta ownership. Google has a translate feature that is quite good generally for AI , content is mostly understandable with exceptions for some gun terms that don't translate directly, for instance the translation uses the English "kick" and "futbol" ( don't ask me why) interchangeably for a butt stock. But by and large the intent is comprehendible for the most part.
You own a Fine Gun, one of the World's Best. It is the easily the winningest double of all time in World Box Flyer competition. I can back that up with a list of World Championships won by Imperial Monte Carlo users before, during, and since my time in Europe/World FITASC and now FEDECAT sanctioned World Championships.
The guns hold a place of reverence in the hearts of Italian shooters.
The gentleman , who is arguably the greatest pigeon shooter of all time in Europe, certainly in his era, when Italy dominated the game, Giovanni Bodini shot one Imperial Monte Carlo his entire career.
A very interesting video clip on Youtube entitled , Tiro a volo di una volta shows some amazing historical footage of Italian shooting in the early post WWII years. Bodini and his field gun (note the sling swivels in the video) with his numerous "customizing" features is frequently shown in the winners circle. The intro to the video shows a view of "Gianni" looking over the muzzles of his gun in competition mode.
I jokingly commented to a pigeon shooting friend of mine, that view was the last thing a thousand incomers saw before being reduced to an X on the scorecard.
I hope some of this is helpful to you in learning more about your gun.
I have a tremendous amount of info/history of developement ,and names of storied shooters who competed and won with these pieces.