Defective case that had a small piece of foreign material in it or just a forming defect.
That's my guess anyway.
If you cut the case in two you might be able to see something out of the ordinary on the inside.
Nope nothing out of the ordinary ( I cut it open ). The pin hole developed right at the top of the web to chamber junction. Flash hole was fine, no burrs or defects. primer wasnt cratered or flattened. So have to go along with the defect in manufacture.
Also dont think it was even close to premature case head seperation due to the fact the crack extends upward from the hole, and not any defects or signs of it going around the head. Most definately NOT getting rid of my Redding Competition dies as they were a bit pricey.
I will watch for it from now on in the remainder of that bunch, but am a little leery of Win brass at the moment. Norma or Remmy from now on.
Thanks for the input
Swifty