The SAAMI psi numbers for the 280 and 7RM are 60,000 and 61,000 respectively.
Max average.
Do you guys know what they placed the 280AI at--was it 65,000?
I don't think that SAAMI has published data for the 280AI, at least from what I've gleaned. However, the limiting factor for chamber pressure is not so much the action, but the cartridge's case head, i.e., the area where the brass is no longer supported by a surrounding chamber. Therefore, the limiting pressure should be the same.
Besides a slight addition in case volume, where the AI's shine is that the case's minimal taper passes more of the rearward thrust into the chamber walls, or so I've heard. That helps to prevent case-stretch and therefore case-life is prolonged.
