Most states would not consider it a muzzleloader so it is likely not legal in most for hunting. I have an original Remington 1858 revolver which was purchased Civil War Surplus by my Grandfather. It was not taken good care of and to make it shootable I ordered Navy Arms parts to refurbish it. The dimensions of the original and the new Italian copies are different. The original used a .454 ball and the newer ones use a .452 ball. The replica cylinder sends balls too small for my barrel so it needs to be reamed out to shoot the larger ball. If you can get a measurement of the face of the cylinder chamber holes I can match it with my replica cylinder and likely verify that it is a replica. The original that I have although basically a ball of rust when I found it in a box with a pile of old chains; once cleanedup with a power wire brush,still has the markings on the barrel "Patented Sept 1858" second line on the barrel reads "Remington & Sons IlionNew York USA" third line "New Model". If yours is an original I would expect to see similar markings stamped on the barrel just forward of the cylinder. I was about 12 when I started cleaning this up. Later I did a fair job of making it shoot although timing the cylinder and replica hammer with the original trigger and cylinder stop was a real job. Mine does not look quite as good as the one you have but I strongly suspect that it is a replica due to the condition of the stock alone.