Look Russ, I am sure you are a fine fellow. Not trying to rain on your parade. As I said, you did some hard work.
I am a scientist by profession and when I see somebody do an experiment, I want it to be statistically valid so I can draw a definitive conclusion (X is demonstrably better than Y for example).
Its not that I am dissapointed or trying to cast asperison of your efforts, its just that you came [b]so close[/b]! If only you had kept the number of rounds fired per group the same.
For example:
If you fire a 15 shot group [i]with the same ammo from the same rifle with all other conditions being the same[/i] and then fire a 5 shot group with the same ammo and set-up, the 15 shot group will almost always be larger.
Therefore if you have two different brands of ammo that are equally accurate in fact and you fire a 15 shot group of brand X and a 5 shot group of brand Y, brand Y will almost certainly give a smaller group and this could lead one to the erroneous conclusion that Y is superior to X when in fact, both are equal.
Even worse, you could have a scenario where Y is slightly inferior to X. In this scenario, the measurer useses a sample size of 15 rounds for a grouping of X and a sample size of 5 for a grouping of Y. X produces a larger grouping than Y leading to the conclusion, on the surface, that Y is superior to X when in fact the opposite is the case.
If you fire equal numbered shot group of both, then both should give equal groupings (more or less). (especially if you use groupings of 10 to 15 shots and take averages amongst several groupings of each)
That is all I am trying to say.