This has been an interesting discussion, and in light of Drew's post above and my comments regarding case hardening based on information from the Jerred family; let me say that the information I received regarding the cyanide burn accident occurring to Charles Jerred while working in that department did not specifically reference LC Smith frame type, he could very well have been working on Fulton box lock frame or something else? Clearly Fulton frames were being hardened using cyanide; but LC frames, I'm no longer sure? In the interim we can look for examples; but I have indeed read a reference somewhere in the past stating that Marlin used the cyanide process on Smith guns, I've just gotten to old to recall the origin. Tom