The easiest way to do real bluing is to use the hot water process. It is labour intensive, but not difficult, and not particularly hazardous, if you can safely boil water.
Do a search for "Radocy". His hot water blue works very well. This method is the classic, used on fine guns for years. Also works very well for small projects.
Hot caustic bluing is a pain. You are dealing with a caustic solution that is boiling at about 290 degrees Fahrenheit, that will give chemical burns as well as scalds. Temperature is controlled by adding water to the boiling solution. Think about it, you are adding water, which boils at 212 to something boiling at a temperature 80 degrees higher.
The bath is easily made using lye (caustic soda, sodium hydroxide) and a nitrate. Sodium or potassium nitrate. Ammonium nitrate will work, but you must mix it up outside because ammonia gas will be produced initially. I made a set up, used it, decided I would rather have any hot bluing I needed to have done to be preformed by someone else.
After preparing the surfaces, boil the parts in trisodium phosphate (TSP) to remove all traces of oil, grease, fingerprints. Rinse in hot water, then blue.
Easiest process of all is Parkerizing. Surface prep, degrease, stew in the solution, which is below the boiling point of water. Rinse, oil.