Hi,
You have a New Model Army sometimes called an 1858 or an 1863 New Model Army. It was shipped in August of 1864. Since nickel plating was not available until around 1870 your revolver was probably refinished by someone other than the Remington Factory.
Regards,
Billt
help with New Model 1863-I think
Re: help with New Model 1863-I think
Anything is possible. However, Remington stopped producing New Model Armies after the Civil War. They continued to produce New Model Navies until about 1880 well after nickel plating was invented.