It's a coating, not a chemical reaction like true bluing, so it should work if you follow the instructions.
Personally I prefer Cerakote (that's all I've used in my gun repair business for 12 years or so with no complaints yet). Cerakote has been proven to be more durable than any of the other firearms coatings but a lot of people like Duracoat in the rattle can as a do it yourself coating.
Doesn't matter what you use, just make sure you meticulously prep the firearm. You want NO oil, grease or other contaminates on it when you spray. Also, it WILL NOT fill in any deep pits/gouges/scratches, you have to fill them before spraying unless you aren't worried about that.