I am going out on a limb and say that all assembled locks have all parts hardened. However, you will find a world of difference in the fit-up and function from manufacturer to manufacturer.
Chambers is the best, hands down, in terms of consistent lock to lock fit and function. Occasional minor fitting and polishing.
Davis is good, L&R is good. They will need minor polishing, a little more than Chambers, and an occasional adjustment of internals geometry for smooth functioning. Sometimes a frizzen needs to be re-hardened, or the toe of the frizzen reshaped, etc. Minor stuff, and by the way, things that are good to learn how to do for yourself.
The only time you need to harden things usually, is when you get a lock kit.