I see lots of people making their own receivers from 4140 or 4340. When making a home made rifle action I think it is important to overcompensate for any possible error by using the strongest metal available. When designing your own action or scaling up an existing design you definitely want the ultimate strength to minimize any chance of failure. I think 17-4 steel is a really great material with tensile strength around 200,000 psi. Another great advantage 17-4 has is it is "precipitation hardening" meaning it hardens at a much lower temperature than other steels, about 950 degrees F. This eliminates any scaling so there is no need to wrap the material. It does not need a quench you just let it air cool. It hardly moves at all from the heat so you can machine your part complete then heat treat, maybe leave your most critical dimensions for a light skim after heat treating. ANYWAY I JUST "DISCOVERED" AN EVEN BETTER MATERIAL: It is called Maraging 300 (Vascomax C300). It heat treats at low temperature like 17-4 and has a heat treated tensile strength of nearly 300,000 pounds. The data sheet also says compressive yield strength 317,000 psi and notch tensile 420,000 psi. It hardens to 50 to 55 Rockwell. Now usually too hard is no good but in the case of this metal the numbers look real good from my limited understanding. It is crazy expensive by the way. Does anyone with better knowledge of metals have any input on this? Does anyone know of any other great materials for receiver making?