Miller you bring up a very good question and one that I cannot answer. The only thing that I can say is that starting in 1912 when Hunter Arms changed the grades from a number to a noun (except the early Monograms) the barrels on most of these stayed with the same name, ie; Field-Armor Steel (pre 1912 OO Armor Steel), Ideal- London Steel, etc. What would make the earlier ones any weaker than the later ones, or vice-versa I don't know.
I think it is as you said, they new their guns could take it and time has proven that.
How many of these guns were handed down through the years and the new owners did not know what the chamber length was and didn't seem to care and just shot whatever they had out of them.
