GT what I found after trying and measuring all the different shell holders and turrets.
None of them measured the same, They all have tolerances.
Of the ten turrets and 5 #4 shell holders i Have it was one particular combo that was the problem.
It did not matter how hard I pushed on the handle or how much I adjusted the die to take up the slack. It would not size the cases correctly.
I could mix a different shell holder with that turret and it would work.
Or use that shell holder with any different turret and it would work.
Believe me, I thought I was going nuts. I checked and triple checked every thing I could think of.
Not fun at all. I would have rather been shooting than trying to clear a fail to chamber from my AR. Those are the ones you have to wedge the bolt back open. Yuk!!!
Measure your holders you will see how different they are. From the top of the holder to the spot where the shell base sits. That distance varies from holder to holder. Couple that with a loose fitting turret. You never will get a case to head space.
Going through that explains why I am anal Annie when it comes to press mounting now. I eliminate any variances I can. hence the steel mounts for my presses. I dont re size using pucks that move or breech locks, No wiggle allowed.( strait walled cases dont count. Or any case that does not head space on the shoulder) Head space can get tricky with rifle cases. Esp in autos.
Do I need to do that? Nah not likely to run into some whacky combo problem like that again.
But I have lowered those odds even more. If some thing goes amiss I can find what it is right away.