44 AMP, have you ever shot rifle proof loads generating 81,000 psi?
No. But I have fired a round that at best estimate generated between 90-110,000 psi. I don't recommend it.
Traditional pressure signs don't show up until you are at 70,000 PSI, which is well over a max load. You could be over the max pressure allowed for the cartridge and still not get any of the traditional pressure signs.
That is unreliable.
What "traditional" signs are those? Cratered primers? Flattened primers? Pierced primers? case head expansion beyond initial .001"? something else?
Those things can, and have shown up at pressures below 70k psi, and under the right conditions can show up below regular working pressures. And as you noted some don't show up at much higher than working pressures.
I think what is unreliable is the expectation that a certain pressure sign will ALWAYS show up at XXXX psi and that a certain pressure sign showing up ALWAYS means you have XXXX psi (or more).
Most of us consider cratered primers to be a pressure sign. They are. But while often a sign of pressure higher than desired they can also happen at normal pressures, because of factors specific to individual guns and/or ammo components.
Perhaps its just the way we use language differently. I consider pressure signs reliable in the sense that when you get them, you got them, and getting them means something isn't what we want it to be.
They are not reliable predictors of anything else, though. Nor do they show up on a "set schedule". Every gun can be different. Every individual round can be different, despite all we do striving for uniformity.
I've seen the same ammo behave normally in all aspects in one gun and crater primers in another.
All our measurements have tolerances and sometimes you get performance at either end of the bell curve when you expect something in the middle.
Not getting what you expect doesn't always mean the thing is unreliable, but it could mean your expectations might be.