Understand your frustration especially with component availability.So I have been firing and loading for this rifle for a long time. Previous to this I was loading strictly Norma brass. The datum line dimension hasn't changed. I check this measurement at the start of each session and have also verified this brass as it came out of this gun. All of these were fired in this rifle so I assumed it all should have stretched.
After sizing all brass goes into loading trays and not just dumped into a pan or bucket. The pieces I found that were "short" were all found scattered throughout the trays in a random fashion. So I doubt I am over-sizing or overworking this brass. Also anything shorter than the 1.460" shouldn't have the shoulder moved anyways just because of the fact it does not reach that part of the die. Also to push it back .010" would require a lot more effort than I am putting into it.
I will accept that some may have been too short to begin with as I did not measure it before I started loading it the first time. But that would mean those 17 cases fired anyways, even after being reloaded. The only finding I could detect with those unfired rounds were that the cases were so short.
My experience with this Hornady brass so far has been amazing consistency on targets. Biggest problem currently is finding any virgin 223 brass. So far all I have been able to find is already primed Norma which I am hearing many misfires with those primers.
I just purchased some virgin brass, Starline, from Midway. I have never used Starline Rifle brass before, just their pistol brass which performed very well. From the reports I have received on this forum from fellow shooters, most reports are positive, so I am hoping my experience is the same. You may want to try some, it was not terribly expensive either.
Long ago, I used range brass too. I just couldn't pass up "free" brass. It worked ok until it didn't - I won't go into the details here. I stopped using range brass many years ago. All I am trying to say is that for precision shooting, I have found it best to start with virgin brass, dedicate them to one rifle, and rotate it's use so all cases receive the same number of firings and sizing. This has produced the most consistent accuracy and reliability for me.
If one insists on using range brass, then prepping it and sorting it dimensional to provide the most consistency possible should help. As far as the inconsistencies you have reported, brass from different lots and fired in different rifles can lend itself to dimensional variations.
I have encountered short case head space even in virgin brass, especially Remington. It took several firings to fully fire form those cases in the rifle I had dedicated them too. During the interim, I did not push back the shoulder. I had one lot of virgin Hornady cases that the case head space was too large and required pushing the shoulder back to chamber in the rifle I was using it for. The point is, sometimes, even with virgin cases, you have to custom size them for optimum chamber fit in a given rifle, at least that has been my experience.