The current production Miroku receiver can handle pressures up to 50KPSI, well into nitro territory. The same receiver is used for .348 with with a max pressure of 46,000 KPSI and and a larger base diameter. Base area times pressure determines bolt thrust, which is the receiver limit, which is why the .45-90 can go higher. The barrel steel is a Japanese take on 4140 and plenty big to hold 50 KPSI.
I find the crescent butt (as opposed to shotgun butt) on many current rifles undesirable with hot loads. I also prefer pistol grip stocks to straight.
