Many rifle ctgs. today, run regularly at 65,00PSI breech pressure. Some very few expamples are .260Rem, .243, 7mm/08, .270Win, and many others, both larger and smaller. Most of the short and standard length magnums run 62,000 to 65,000PSI.
: For something frightening to contemplate, even the NEF break-open single shots are chambered for the .243 and .270Win., both at the extreme top end of the pressure range. Even the new LowWalls by Browning were chambered for the .243. Actually, I should have said even the new NEF's as I'd trust the brand new Low Walls before the break-guns.
: The switch from Copper Units of Pressure to PSI has been a painful one as they aren't directly transferrable in numbers in most ctgs now used - very few in fact, and only at some prssure levels are they equal in number - some pistol and the odd straight-case rifle rounds. Reloading data is being rewritten, both up and down from previous posted maximums when changing to Pounds Per Square Inch. Many sourses interchange these names.
: The Rugers were 'proofed' BEFORE PSI came into the lime light. I'd expect they were tested at CUP units of pressure, a full 70,000 of them. Since most of the rounds mentioned above run 50,000 to 57,000CUP, it stands to reason CUP was the unit used in testing the Rugers, not PSI - a different kettle of fish entirely.
: I-for one, certainly don't condone loading to levels the brass itself wasn't manufactured for.
: Hope this helps shed some 'light' on the CUP/PSI problem.
: This is, as I understand the phenominum.