It appears to be a replica of a Colt 1851 belt pistol, often called a "Navy".
Another photo showing the entire side view of the pistol would help to confirm my guess.
Your gun is somewhat unusual because it has a "square back trigger guard" on it.
Most of the Colt 1851's have a rounded back on the trigger guard.
Several companies offered (offer) square back guards on their Colt 1851's and the trigger guard has been sold by itself so a owner could install it. In other words, it's presence does not help to narrow down who made it.
The second picture with the letters PN and the shield are Italian proof marks.
Somewhere on the gun you should be able to find a square or rectangular box with letters or Roman numerals in it. These letters will tell us when it was proof tested.
Over the years there have been several Italian companies that have made these guns.
Many stamp their companies name or symbol on them but I didn't see any pictures showing these.
The 62924 is the serial number. The 26 on the cylinder arbor is a assembly number.
The name under the grips is from a previous owner, now long forgotten.
If you want to shoot your pistol you will need some .375 diameter lead balls, some black powder or one of the synthetic black powders like Pyrodex or Hodgdon Triple Se7en and some #10 or #11 percussion caps.
There are lots of topics on the forum describing loading and shooting these Cap & Ball pistols.
