Having shot many 7.62 NATO proof loads in Garands that produce 65,000 cup or about 80,000 psi and none showed any signs of pressure on the case or primer, folks claiming one can look for signs of pressure may be leading others astray and into dangerous territory. MIL-SPEC normal max pressure's 50,000 cup or about 60,000 psi. Any data you see will be effected by how hard or soft the brass is in both the primer cup and cartridge case.
My advice is to load 8.57 Mauser no hotter than what decent data suggests. Not all M98 actions have the same strength, so why push the envelope when you don't know how strong it really is? Which is why SAAMI specs for 8x75 ammo's no higher than 37,000 cup or 35,000 psi.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master