OK
RC: You are correct about the normal use of the terminology....Case separations most frequently occur at the web or a bit above it.
My experience with the 5.7, though, is that the neck does not split....there is a complete separation at or slightly above the shoulder. The neck remains in the chamber and prevents the following round from chambering. I attribute that to metal fatigue. Perhaps I am wrong....I wish, though, that I had a few cases to show just how much the shoulder blows forward upon firing. There is a lot of metal moving both upon firing and again at resizing. I am careful about headspace....measuring cases and setting dies. What I have found, though, is that the sizing die will not set the shoulder back far enough unless the ram over cams.
Suggestions welcome.