Yeah, I know. This stuff all got very, very complicated.
There is an N scale and an R scale. The treatment that had to be used on this metal, and remember I had the metal analyzed by Arrow labs, as a nitrite case hardening. This produces an N scale hardening. Basically the metal is hard on all outside surfaces but the center is not nearly as hard. Result is that you get a very hard surface for about .001 to .002". Kinda like an Oreo. The interior metal is still flexable. Hence you get excellent wear properties on all outside surfaces, like the pin holes, ejector, rails etc. without the attendant brittlness of a real hard rockwell all the way thru. These will be perfect for AKs which have a lot of flex when firing.
It took a lot of time and we trashed a few receivers between cuttin' one up for the metalurgy and trying different tempratures and times at the heat treaters.
All involved feel this is the optimum solution for AKs and solves the problem of these excellent but formerly dead soft pieces.
Denny