What you have is an model 1858 Remington. Caliber should be .44 or .36 It needs to be soaked in Kroil Oil or Kerosene for at less a week to loosen parts. Remove the wood grips first. Do NOT clean with steel wool. Use brass or bronze wool and oil to remove surface rust. This will not effect the patina. Use boiled linseed oil on the stocks and do not polish the the brass.