grogel,
Take off the wood. Rust bluing is applied with a wipe or swab of some sort and often the metal under the wood is left bare in some places. Caustic bluing is a dip method and all surfaces, even inside the bore are blued.
Caustic blueing looks more like your early examples with a deep blue-black and very shiny surface. The rust blued 99 I saw had a very fine matte surface with some shine.