All springs and other internals would be stripped out of the frame befoe CCH. As for the external hammers, that would likely depend on how closly fitted they are to the lock plates. If so closely fitted that the charcoal mix couldn't get between the backs of the hammer and the lockplates (to impart coloration during quench) then they'd definitely need to be removed. My guess is that the hammers would be removed in most every case, but that is just a guess. Maybe Brad will tell us how he did it in his fourth photo posted above.

Parker Hardening
 

Parkers are Parkers because they were "hard fitted" during final assembly. The parts were soft fitted and numbered to the gun. The individual parts were then hardened. The hardened parts were straightened if necessary, and hand fitted for final assembly by the "hard fitter".

Best, Austin