Blueing tank temperatures are no different now than they were 100 years ago. 275 °F to 310 °F (135 °C to 154 °C).
If the Savage 24 barrel is even connected over its whole length, you want "Rust Bluing".
It's not the temperature, it's the chemistry. Hot bluing salts contain a lot of sodium hydroxide (lye, caustic soda). It has no effect on the steel, its purpose is to raise the boiling point of the solution to where the nitrates will work.
Hot lye will dissolve soft (lead based) solder. Don't do it.
