Re: .280 Remington
I don't know if this is useful or not but here goes: the SAAMI spec for a .270 is 54,000 PSI and the .280 spec is 50,000 PSI. The reason it is lower is the .280 was originally made for semi-automatic rifles with are not as strong as bolt actions. Many shooters I know give the .280 "another grain" to load her up to .270 pressures in bolt action rifles. If it's a pump or a semi-automatic action, stay below 50,000 PSI. The same is true of 30-06 also, 50,000 is usually the top load shown and I have done this with both 30-06 and .280 myself when reloading for these cartridges in modern bolt action rifles.