ODIE, Well since you asked .... Your Wr ......... !! No actually your quite correct. Case Hardening was the most common for the original "Iron Frame" guns. Must remember, those guns needed to be Cased as well as heat treated. The Iron was some soft.
That isn't to say that many weren't manufactured without hardening. They were, just as were Colt. Biggest problem when reconstructing the past, none of the reconstructors were there, to actually observe. We mostly guess. Black and White Photography wasn't real indicative of actual appearance either. Since the known collections only contain a small fraction of the number actually manufactured, Where on earth are the rest of em??
PS: I couldn't help but notice, the rifle the nice lady has in hand is LOADED!! So often the follower is back against the frame. Some of the "still" screen grabs, unfortunately, have the rifle with the follower all the way back (sigh)