I straighten it out completely, put a small 90 degree hook on one end, sharpen it on the inside edge and then run it in to the casing base. When withdrawing, you will feel a dip where the case wall expanded to the chamber's wall. If the sharp hook catches on the forward side of the dip, you have potential incepient separation.
The best indicator is when you can visually see a thin, bright shiny ring in the same area on the outside of the case. When first starting, it doesn't go all the way around the case.
When noticing that I use the paper clip. if there is a dip like mentioned it goes into scrap after crushing the neck. Usually at that point it's only a firing or two from total separation. Watch the other cases in that batch..... they aren't normally far behind.
Nothing screws up trigger time like a blowed in 1/2 case thats stuck in the chamber.
As an aside, if you've followed Vamint Al's finite element modeling activities, you'll have noticed he's got one that shows a highly polished chamber tends not to form sharp pressure rings, instead distributing the stretch over a somewhat greater length of wall. In another FEA he shows the additional bolt thrust produced due to polishing is only around 5%, IIRC? Not the big problem conventional wisdom makes it out to be.
First I've heard of that Nick. From what you recall do straighter walled case fair better? It would seem the heaver tapers might not stick as much and flow out more evenly ..... just the opposite of what would be normal.
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