probably proof markings
Where it was made, proof marks, etc..
From markings and proof marks on the gun barrels and the frame. In some cases you need to remove the barrels, and look on the underside from markings.
These are mostly proofing marks and caliber and barrel length markings. There are books on the market that define Belgian proof marks
Without seeing the markings it is impossible to answer precisely. It is likely that you are looking at proof marks. European nations require that firearms be submitted to a government testing facility (a Proof House) where firearms are tested by being proof fired with a high pressure test load. Guns that have been "proofed" are stamped with a symbol to show that. Each nation has different symbols for different types of guns. Research the term "Italian firearm proof marks" to see examples.
Depending on the rifle, it may not be possible. Modern reproduction rifles are usually marked with the makers name. However, earlier authentic antique rifles may not carry a maker's name, and may have only a proof mark. Identification will usually start with recognition of the shape and style of rifle, proof marks if European (the US does not have government proof houses) markings on the lock, and markings traditional to a given maker or region of the country. It is as much an art as it is a science.
inspector marks, sn, proof mark, etc..
Depends on what they are. Could be choke markings, proof mark, etc..
Slide markings and proof marks are used also.
In order to get an Italian passport you need to be an Italian citizen. The same applies to any country's passports. That is the purpose of a passport, it is a proof of citizen. So the question is really: are you an Italian citizen? Or can you get Italian citizenship (naturalisation or because one of your parents was Italian).
Do a Google search on Italian proof marks.
Barrel marking include the proof marks, choke code and weight of the barrels. Please be specific and we can give a more direct answer.