Thank you for the very good photos, particularly the ones showing your bullet in the jaws of a precise-measuring Caliper -- which saves us the effort of asking you to do that, and waiting for your response. Your bullet's diameter measurement means it was made for use in a .58-caliber rifle. That, and its body shape, means it is from the civil war era.
It closely resembles a yankee 3-groove Minie-bullet... but the definitive characteristic of a Minie-bullet is that it has a large cavity in its base. (Most often, the cavity was cone shaped.) Your bullet seems to not have a base cavity. Or perhaps the cavity is there but filled with crud. Please check that for us and let us know.
