All of these old rifle receivers were made from plain carbon steels. The ones used in the Springfield rifles are well know to Americans because of Hatcher's Notebook.
The steel used in the single heat treat receivers and the double heat treat receivers were the same. Looking at data on Matweb, the low carbon steel used in these early receivers is not used for complicated parts, unheated it is used for rebar, if heat treated for medium duty shafts, studs, bolts and nuts.
I did a composition search and found AISI 1117-1118 steel, which is similar in composition to Class C steel. I could not find something that was just carburized and quenched . I found data for 1 inch round AISI 1118 mock carburized, reheated to 1450 F, quenched, tempered. This is similar to the double heat treatment. The Ultimate strength is 103,000 psi, yield 59,300 psi, elongation at break 19%. For something similar to WD2340 Nickel steel, which is an alloy steel, I found one inch round AISI 4820. For that material, mock carburized, 1450 F reheat, water quench, the ultimate strength was 163,000 psi and the yield strength was 120,000 psi, elongation at break 15%. It would appear to me that even the best of the double heat treat receivers have a low yield strength compared to an alloy material and less elongation before breaking.
Today, no one uses rebar to make a complicated and expensive part such as a rifle receiver, but that is what was used on all of these old military receivers.
Plus the problem is, the composition of the materials varied so much, how can you get the correct heat treat temperatures for the thing?
Even double heat treat receivers may be brittle.
http://www.fulton-armory.com/LNSpringfieldLowRes.pdf