cm: regarding original factory heat treating processes as compared to re case hardening, when a factory heat treated a receiver the metal started out soft and to a known spec as rolled or cast or perhaps annealed to a known spec.
an after factory re heat treating process starts with a receiver that has already been factory heat treated to a known spec. as I understand it, the first step in the re heat treating process is annealing, which destroys the original factory heat treatment of the receiver. step two is coloring, via cooking the receiver above critical temp in a high carbon environment. step three is rehardening the surface of the receiver metal via a quench. and finally step four is tempering the metal back to a less brittle, more elastic state. much of the specs used in re heat treating processes are developed by trial and error, as much of the original factory heat treating specs have been lost...what works for one brand of shotgun receiver, does not work for other brands. and as I understand it, what works on say a parker receiver, vintage 1880, will not necessarily work for a parker receiver, say of vintage 1935, and so on. the tricky part seems to be the tempering step. this is where many inexperienced case hardening mechanics go astray. as you have worked for one of the more successful firms engaged in re case hardening, I would be interested in hearing about your experiences.
as previously indicated, a low heat, chemical process recolors the receiver only and does not change the original factory heat treatment of the receiver... some like the appearance of chemical induced case colors. some do not...perhaps it is best to just leave a fine old gun alone and let it be as is? but, if you must recolor, it makes more sense to me to not mess with the functional parts of the gun, particularly the receiver. better to keep it as originally manufactured and avoid the unintended consequences of reheat treating receiver metal.
Last edited by ed good; 05/31/13 08:45 PM.
