With modern actions and brass, there is a tendency now to ramp up pressures to make small cases do large things. All sounds good on paper but just remember that 65000psi is the SAAMI max for ALL magnum cartridges.
80,000psi is the usual PROOF pressure used to test actions.
Custom actions are still made from 'common' grades of steel used in commercial actions. They are just machined to much tighter tolerances. Their overall dimensions are also near identical to the Rem 700 so there is not extra 'meat' there.
They are still subject to the same material yield characteristics. I am no metallurgist but have heard and read from some who say they are, that these steels fatigue at a much higher rate when certain peak pressures are met.
At 65,000psi, the action might last nearly forever. At 80,000psi, substantially shorter lifespan. Get to 90,000psi and things wear out ALOT faster.
For the performance that BR cartridges are sometimes run at, their peak pressures have to exceed 65000psi by a significant margin. No one is brave enough to put a strain guage to find out.
Maybe, no one wants to know.
Custom actions have been in service long enough now that the oldest ones have digested alot of toasty shells. I hope that there will not be failures. maybe looking/testing for stress cracks might be in order.
Looking at the pics of the case comparison, my estimate for case volume looks to be right on. If this wildcat reaches STW performance, it has most certainly exceeded 65000psi.
80000psi proof loads eject from a factory action with 'no pressure signs' and easy bolt lift - I have some test cases. In a vault tight custom action, how much higher can you go?
Most test labs peg catastrophic failure of common actions at 120,000psi.
Jerry