Armies are funny things. They'll spend a mint giving everybody new dress uniforms or coming up with a new tank or something, but they get all parsimonious and skinflint-y when it comes to things like ammo or boots. Back in the late 19th-early 20th Centuries, rifle technology was changing by leaps and bounds, and it must've been hard to keep up, so there were lots of ways armies would wring one more decade out of obsolescent gear...
The army of newly-unified Italy adopted a version of the bolt-action Swiss Vetterli rifle, simplified by ditching the tubular magazine, as the single-shot M1870 Vetterli in the 10.4x47R black powder centerfire chambering. In the late 1880s, with France, Germany, and Austria-Hungary having adopted repeating rifles, Italy began issuing a version of the Vetterli fitted with a four-round box magazine designed by an Italian artillery officer named Vitali.
|Vitali-pattern magazine, seen here on a Dutch M1871/88 Beaumont-Vitali.|
When the Great War finally arrived and Italy joined in on the side of the Allies, the meat grinder of the Isonzo front used up men and material at such a ferocious pace that Italy began breaking the old M1870/87 Vetterli-Vitalis out of armories. Fitted with 6.5mm barrel liners and Mannlicher-style magazines, they helped make up for losses and equipped some fraction of the huge number of hastily-conscripted replacements feeding the corpse fires of the front.
These M1870/87/15 rifles still used the old Vetterli-pattern bolt, with its smallish locking lugs at the rear of the bolt body. While adequate to the task of a limited amount of fire, their ability to absorb extended use of the >40k psi smokeless rounds is questionable at best.
Were it me selling such a gun, I'd place a note explaining the history of the piece and cautioning against firing anything but light handloads on the thing, just as a legal CYA. Perhaps even sell it with the firing pin in a separate ziploc baggie. But that's me.