FredC wrote on Mar 27^th, 2020 at 2:29pm:

. . . if 303 rounds are loaded to 49K Cup then this thing has operating at 30.06 pressure levels for some time. . .

This topic demonstrates the level of confusion arising from old and newer pressure methods. By current SAAMI standards Maximum Average Pressure (MAP) for .303 British is 49000 psi measured by piezo transducer and 45000 CUP by the old copper crusher method. These pressures are actually the same - it's only the method that's different. Old publications from before general adoption of piezo equipment usually express crusher pressures as "psi", leading to many misunderstandings.

The latest SAAMI publication I have doesn't list a transducer pressure for the .30/40 cartridge (probably due to low production) but specifies a MAP of 40000 CUP (crusher). While the difference between this pressure and the .303's 45000 CUP is substantial, it's not what I'd call catastrophic. In addition, the .303 cartridge shown in the auction is likely Winchester commercial 180-grain - not necessarily loaded to maximum pressure.

Table below comes from an old Hercules data booklet -

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