The SAAMI spec for 500S&W pressure is 65,000.
Unless H&R/NEF specifies a lower than standard pressure for it's 500S&W, the rifle will have to be able to handle it.
Average loading data for this cartridge stops at around 50 to 55k...why I don't know.
My question is this; If the H&R can handle these pressures, why can't we get magnum RIFLE rounds in this rifle ?
The 500 S&W has a larger case head than the 375 H&H, so the case head force arguement is no longer valid !