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sounds like there is some dispute as to where the case head space on the 357 sig is measured from .
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The problem is one of technical design and theory versus the reality of real guns and brass.
The only point in the phone call with the SAAMI guy was a little less than pleasant was when he brought up .357sig and said it's headspaces on the mouth. I started to say something and I said it "...headspaces on the mouth, in theory..." and he cut me off, stating that "it's not a theory, there's absolutely no question, you can check the diagrams."
I didn't argue with him, but I did tell him that I do load .357sig and none of my cases are long enough to headspace on the mouth. The more detailed story that I didn't get into with him is that I have loaded the Sig with 3 different brass brands in 3 different barrels. Of those, I have yet to see a SINGLE case that was long enough to headspace on the mouth in a SINGLE barrel.
It's not even close, every case is MUCH to short to reach. They either headspace on the shoulder, if you size them so they do, or much more likely they headspace on the extractor.
Fact is, most semi-auto pistol rounds are actually headspacing on the extractor, no matter what the SAAMI diagrams say.