I see that now and then for some calibers. Take a look at the test platform to see how comparable they are. Still it emphasizes how each firearm is a law unto itself.
Having had a little experience w statistics, I start wondering how they get away with using 1-3 guns to develop loads.
It would probably be much more statisticaly rigorous (and EXPENSIVE) to use a sample of 5-??10 guns.
I've wondered if any of the powder makers test loads multiple firearms of the same cartridge?
Like others have said, start low and work up.
liberal Justice Hugo Black said, and I quote: "There are 'absolutes' in our Bill of Rights, and they were put there on purpose by men who knew what words meant and meant their prohibitions to be 'absolutes.'" End quote. From a recent article by Wayne LaPierre NRA