Thank you for posting that. I have had arguments with other gunsmiths who stated it was absolutely impossible to achieve a case hardened surface if the parts were quenched below critical temp.
Having done experiments myself, I know this to be untrue. I have quenched with temps down to 1150 F (after holding in the 1400 range like Mr. Gaddy recommend) and have had parts that stood up to very heavy filing without being able to break through the case. And more importantly, very minimal to no warping.
It is nice to read Mr. Gaddy's very detailed description of the science behind why that is true. I will commit it to memory.
