Here's what happens when brass necks have been overstressed by reloading. This is why brass needs to be checked not only before reloading, but after and during the process. This is 35 Whelen brass that was necked up to .375 and then neck sized back down to .358 to set a false shoulder for headspacing. The brass was just a little too old and this is what happens. This didn't happen when firing it as you can see there is no powder residue outside the cracks. It happened after the stress of reloading. Check your brass often.
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