Quote Originally Posted by Dimitri View Post
The best materials for recievers out there are mild steels, that is steels with under 0.4% carbon content as you want the receiver to flex in the inner core, while having the hardened case to handle the loads without shearing.

For example the M14icon line of rifles use 8620 steel, its a nickle-chromemoly steel, low carbon content (a mild steel) which is case hardened and in the M14 platform handles a life of 425,000 rounds.

Only tool steel I'd trust in a firearm other then 8620 is probably S7 or similar, as they are designed to be shock proof, running a piece of metal that is all the way through hardened can cause very large problems due to the shock loading that a firearm receives.
Dimitri
Earlier you posted that you might be interested in a Remington 700 custom shop rifle.
It is common knowledge that their receivers are made from 4140.
I believe that Ruger M77 bolts and receivers are cast from the same or a similar alloy. Care to elaborate on the contradiction with your statement above?