That revolver dates from the era when S&W nickel finish was electroplated over a copper wash. Copper solvents of any type should not be used on that revolver. The only nickel finishes safe for copper solvents are ones that are plated with electroless nickel as that nickel finish variant does not require a copper wash coat. The copper solvent attacks electroplated nickel finishes by getting under the nickel and attacking the copper base coat.
When in doubt, use a CLP like Break-Free and avoid anything with ammonia or anything marketed as a copper solvent or cleaner.