In my opinion
....Original internal parts (by "original" I mean the original parts in some of the replica revolvers) were less than perfectly heat treated.
In fact some of the builders of kits from the seventies recommended that kit builders get smart about heat treating.
Parts for ASM and ASP are hard to get and so repairs and replacements are done with Pietta parts or Uberti Parts or other parts which are not specifically designed for the replica in question. They need to be fitted and most often this is done by filing on the replacement part and so even if the part was heat treated, that hardened metal may be removed during the fitting process.
So the problems are:
1) Properly fitting parts are not easy to find and many times you don't know until you get the parts.
2) Parts which don't fit need to be worked to get the pistol functioning properly.
3) The working of the parts MAY or MIGHT reduce their hardness and consequently their reliability in the application.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson