You are assuming that changes in propellants or other components will cause a large (dangerous) change in generated pressure. If this was the case, we would have read about Hodgdon recipes and others causing firearm to self destruct. I say Hodgdon because they never used to publish bullet manufacturers, just things like 50 gr, or 60 gr loads.
i have never seen a warning in any manual advising users to confirm the book load with a chronograph before attempting any loads in their book. I have read that reloaders should work up loads and not jump to the maximum. I do not believe that any company will publish information that is clearly dangerous or irresponsible. If you cannot trust a manual published by a major manufacturer, then I would suggest you shouldn't be reloading.
Oh stop it. I've had soft brass produce bodacious ejector marks with minimum powder charges with several different powders. I've hit max listed velocity with less than max charge before and have had max charges be well below max listed velocity (accounting for bbl length) before also.
Changes in components can damn sure change the pressure equation.
