Okay... ** deeeep breath** This rifle was originally a single shot in 10.4x47R caliber. Italy paid a fee to Vitali for the use of his magazine system to make it a repeating rifle. So did the Dutch, but that's the stuff of a separate post.
In the dark days of WW1, Italy was short of rifles for line infantry but something was needed for training & other rear echelon purposes. So. Over 700,000 of the Vetterli-Vitali repeaters had the Vitali magazine removed, the bore drilled out and a 6.5x52 caliber liner soldered in place. A new magazine system was installed, so strictly speaking, it's no longer a Vetterli-Vitali.
The new magazine uses the same clip and ammo as the Carcano. In practice, you open the bolt, stuff in a clip containing 6 rounds and blast away. When the 6th shot is chambered, nothing is left to support the clip and it simply falls from the rifle.
Another is stuffed in from the top, and the shooting continues.
You will see a number of marks on these. On many there is "PP" on the top barrel flat. This means "Interchangable parts". A big deal in those days. On the stock will be a conversion to Vitali cartouche ( which may or may not still be there ) and another showing conversion to 6.5 caliber. This will almost always have "Roma" somewhere in it since nearly all the conversions were done in an artillery facility in Rome.
There can be other marks & I'll try to explain them as best I can.
They are neat old rifles!
SW