As far as I know, all steels can have a case of higher carbon alloy applied via the case hardening method.
This is I believe "Technically" true.
However, here is a quote from Machinery's Handbook (old edition) "A low-carbon steel containing, say, from 0.15 to 0.20 percent of carbon is suitable for casehardening. In addition to straight-carbon steels, the low-carbon alloy steels are employed. The alloys add to casehardened parts the same advantageous properties which they give to other classes of steel."
From another section after defining carburizing (heating the part in a carbon rich enviroment until it absorbs a "Skin" of high carbon alloy);
"When a carburized object is rapidly cooled or quenched in
water, oil, brine, etc, from the proper temperature, this case becomes hard, leaving the inside of the piece soft, but of great toughness."
The key here is these low carbon steels are not subject to through hardening, the low carbon core not responding to the quench, this is however not the case when higher alloys are used. In this case either the core properties or the case properties will not be that desired. Heat-treated steels having a higher alloy of carbon will "Normally" be tempered or "Drawn" to a higher temp in order to give desired properties to the part than will that of a case-hardened part. To draw to these temps would simply wipe out the advantages of the case.
This leaves us with the fact on these steels it would be for decorative purposes only. The risk of detrimental properties is to me simply too great for me to risk on a gun of mine.
But then of course I am not real keen on "Re-Casing" older guns anyway, as there is still a certain amount of risk involved. My "Field grades remain field grades, so have had no reason for annealing an action, thus no reason other than cosmetic for re-casing. I have simply learned to enjoy them as they are.
