This is true. My consideration was how the barrel was reamed. I wasn't clear on if the barrel was a factory chamber or if it had been set back etc... If it was rechambered or set back incorrectly and the back end of the reamer was off center, That could possibly open the mouth of the bore an extra .XXX and not support the area just above the web. Some of theose cases look large above the failure. Whatever the issue is it affected both resized and factory brass. So I'm thinking the cases are not the problem. It headspaces good. all of the other dimensions are good. Maybe the bolt head and the counter bore diameters need to be compared, if that has not already been dismissed. What else can it be?
Edit. After looking at the print it would be .010 loose. But it should not be say .020.
Fish