.400 NitroExpress.30/06 brass with is the same as .25/06, .270, .280, is loaded to 63,000PSI in the smaller calibres. Due to the weaker Springfield rifles and actions of the 1st war, '06 ammo itself is held to lower pressures. For modern rifles, wiht handloads, it's pressure allowable is the same as any other calibre on the same case.
; Due to it's larger bore size and attendant greater expansion ratio, the 8mm on the '06 case will exceed any ballistics the .308 cal.'06 can produce, with the same bullet weights,at identical pressure.