This has been mentioned before but it bears repeating it is a safety issue:
According to Tom Armbrust, any reported pressure testing of 2" shells that were tested in longer chambers doesn't reflect true pressure in a 2" chamber. Boyle's law at work. I only know of one tester that has 2" chambers for testing and that is Big Bore Ballistics which is located in Ft. Valley, GA. If there are more, I am curious. There are some modern 2" chambered guns that were made to be compliant with modern standards, either European or American. The 1930's English guns weren't. Last year there was a long thread on this subject and it is a shame that Mr. Ed, the talking horse, died while being beat to death over this issue. I was in there swinging, too.
Published pressures by commercial shell manufacturers may only be accurate for that flat of shells tested and are no guarantees that the following run will have the same pressures as companies are controlled by SAAMI limits and companies will often load to that limit if that's what the components used will yield. Components may vary in a particular brand which can mean pressures can vary but will always be below SAAMI. RST is the exception. If it says low pressure, it is low pressure. At least one of the well known testers refuses to test factory ammo because of the year to year or run to run variation. Probably a matter of liability protection for the testers. Gil
