New Lapua, Nosler, and Alpha brass run out.
 

I just checked all three of these after running them over a Sinclair expander mandrel. All are good, but not the same. Lapua has 0.002, Nosler 0.001, and Alpha 0.000. All my new domestic brass is sealed in bags so I didn’t run any of that, but from experience it might be closer to 0.004. Not that this tells us much, but it is a comparison that can be measured.

So Chuck, can you tell if the run out is caused by variance in neck wall thickness at different points on the neck or is it the neck isn't perfectly straight and has a small tilt to it?

I’m almost certain that neck thickness is uniform. On Winchester or Remington brass the opposite is true.

So once you run them through a good sizing die they should all end up at 0 run out. Sounds like pretty good brass all round.

What is the effect of the expander mandrel? Can it impact run out?

Honest question. I've never seen one.

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The Mandrel, in this case, will reduce any run out due to a damaged neck. The mandrel floats, so it should not induce stress. Alpha brass is packed in such a way that necks are not damaged and there is no difference in run out before and after.

I use bushing dies so will let the rifle chamber iron that out. :-)

Another observation is that five cases in each lot are all virtually identical run out wise. This tells me it’s the die forming the brass during manufacturing that is causing it.

So the results are only applicable for the cases coming from that one die. There could be variances among the individual chamberings.

Absolutely. And most certainly variances in lot numbers as well. I do not think that the run out in any of this brass will be noticeable down range. At least for me.

Does anyone have different results?