To be clear, I was not arguing against your point.
No bud he’s arguing with me. So since I have been trying to find time to correlate the data from 5 firings which will give me an actual statistical base for ES/SD but here goes.
The test load is 24 grains LT32, Speer 52 match with 7 1/2 primers. The test bed is a Cooper 21 223. All rounds were ~.001 BTO seating. Chronograph Oehler 35P. The reason for the test was how much difference between commercial 223 brass and 556 brass but it fits.
I took rounds fired in a AR of Norma and Federal 556. 10 rounds of Norma that were found to be within .5 grains weight and not in need of trimming. After sorting by weight I did rough case capacity calcs. At the same time I took 10 rounds of various by weight Norma and federal 556 that also didn’t need trimmed ran the calcs on those also.
So on the second firing this is what I came up with.
Norma 556
As you can see weight is within .5 grains and case capacity is within .5 grains.
Next is random case weights ~8 grains. Case capacity ~7 grains.
Now if you notice the variable weight cases shot within 4 FPS of the weight sorted. Also notice they had a much better ES/SD than the weight sorted. 😳
Must note though case capacity was pretty much a wash. This trend on subsequent firing has held up. The ones that started as random weights still out perform the weight sorted. Not by much but it’s there.