I'd probably soak it in some hot tap water. Stick the gun in it and let it dry for a day or two. Honestly though, I have bunches of dummy guns for holster making and I'd use one of those.
After it dries, I'd treat it with a thin layer of Neatsfoot oil. Just wipe it on then wipe it off. Leave it to soak in over night then finish it with some Tan-Kote. After that dries, I'd give it a good buffing to make it all purdy and shiny.

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