old roper, those two nodes you referenced in Al's page towards the bottom are in the length wise axis of the case. I'm referring to the pressure ring height around its circumference on the case relative to the circumference at the front of the extractor groove; the pressure ring's highest point above the case body behind it. It's easy to see by watching reflected light from the case as you spin it; there's less bulge on one side of the case than opposite it.
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