Could be closer, however the factory .318 is listed as 48,000psi and factory ammo, IIRC - 2,400fps with a 250gr.

The .338/06 standard, not imp. by A-Square is now listed in SAAMI and the max. working pressure is listed as 63,000PSI - 2,000psi less than a .270 Winchester for some reason not known.

The .338/06 will drive a 250gr. at 2,500fps - I've seen listed as high as 2,600fps, which is only 100fps slower than a .358 Norma Mag. Must be a FAST 26" bl.

The Ack. IMP version easily makes that and a bit more, especially if the neck is shortened by .050" to 1/10".