I recently purchased one from a fellow forum member. The prior owner did an antique
finish on it and it looks 160 years old but is unfired. I have yet to get it out to the range but that will be remedied soon. It is an Armi Sam Palo. The fit and mechanics are very good and like all 1858's I've handled the main spring is very stiff. Before this I have only owned open top revolvers.
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Your pistol looks like a Remington-Beals Army revolver reproduction with a later modification done to it.
The Beals model was the first version of the Remington Army pistol and about 1900 of them were produced in 1861-1862.
This was the pistol that Remington sent to the Army for testing. The Army liked the gun in general but they found a few faults with it which prevented them from ordering a large number of them.
The first thing they didn't like was the pistol lacked a way to safely carry it if all of the chambers in the cylinder were loaded. the originals did not have the "safety notches" in the back of the cylinder. To correct this, Remington redesigned the rear of the cylinder to add safety notches between the cutouts for the nipples. The fact that your version has them is the reason I mentioned the 'later modification" above.
The second thing the Army didn't like about it was it easily became jammed because of fouling building up on the front face of the cylinder after a few shots were fired.
To correct this, Remington modified the frame of the gun so that the rear of the barrel protrudes from the frame towards the cylinder. This allows the sharp threads on this end of the barrel to scrape away the powder fouling that builds up on the face of the cylinder.
Notice in this comparison picture how the Beals has very little gap when compared with the later Remington 1861 Army version.
As you mentioned, Armi San Palo made these Remington-Beals pistols reproductions. They have been out of production for many years now.
Although it, like the original may have some problems with the fouling, I think owning them is something special. They represent part of the history of the cap & ball pistols.
Enjoy your new gun.