In Europe, the CIP pressure level for the 57mm case, is 57,000PSI.

The 2 American makers, RP and WW of 8x57 ammo, load them with .321" bullets and to only 34,000PSI.

I recall one of P.O. Ackley's experiments - standard chambered .30/06 (probably a Springfield) with a .308" groove diameter - shooting 150gr. bullets using a normal IMR4895 load. the velocity and pressure was recorded.

They went to sucessively larger 150gr. bullets - then at .358" 150gr., had to run a .35Whelen reamer in to allow the .35 Remington 150gr. bullet to be seated and chambered for proper neck clearance.

Still using the original load, that one fired just fine, indeed, Ackley reported higher velocity and lower pressure with each increase in bullet size. They didn't know why, but it was exciting for them to observe this. They did this test due to the print stating a .323" bullet would blow up a .318" barrel. Ackely proved that if the chamber had the neck clearance, the larger bullet greated no such danger. perhaps the danger was actually firing modern 8x57S (57,000SPI) ammo in an old model 1988, not the 1998.

The logistics noted were that the powder peaked pressure some inches up the tube and by then, the bullets were of course, the correct size for the bore as they'd draw down in the throat itself, when pressure was much lower. Perhaps this heavy drawing increased initial pressure, but that seemingly was not detrimental to the rifle nor the test.

He then spoke/wrote of WW11 or perhaps pre WW11 German experiments that had an 8mm barrel taper bored and rifled with a .257" muzzle groove diameter. That one gave outstanding velocity/pressure stats but due to being so difficult to rifle, the project was abandoned. This was reported in the #1 book, I think. My memory isn't what it used to be Please forgive any details missed.