ScotChapon, it is about being able to keep up with two thoughts at once, you are correct, trimming after sizing is not an option.
Trimming after sizing is the #1 answer, as always with #1 answers deductive reasoning says there must be a #2 answer, back in the old days a reloader went into mortal combat following instructions, the case pilot was was too large for a case after the neck was sized, but perfect for a case neck after firing, because these things do not lock me up, I trimmed then sized, others discovered the Internet, then started grinding, filing and sand papering while turning the pilot with a drill.
Back to progressive and trimming, I measure case length first, I am not going to crimp bottle neck cases, I am not going to crimp bottle neck cases that are not the same length, again, this stuff does not lock me up. I have bullet hold, everyone else has neck tension, I can measure bullet hold, I can not measure neck tension.
I have a couple of boxes filled with regulators and PSI gages, I could do the .7854 thing and use air to determine bullet hold, the thing that locks me up is the neck tension thing, nothing I have converts neck tension to psi, bullet pull etc..