Each cartridge has its own max pressure i.e. .243 Win.. 60,000 PSI, 6.5x55.. 45,000 PSI as stated by SAAMI.
Presumably these are worked out so the max pressure is safe in all rifles, so lets say the action of a 25 year old rifle.
Surely a super strong massively over engineered custom action, made from materials that were not even available when the SAAMI max pressures were developed can handle significantly more pressure than the 25yr old action ?
So therefore is it not 'safe' to creep north of book max loads with a custom action ?
Anyone wildcatting is already doing this.
PLEASE NOTE... This is a hypothetical question, I am in no way suggesting that max loads should be ignored. Safe loading practices should be adhered to at all times.