Intentionally Fluted Chamber????? Wow!
Never thought that anyone would do that on purpose. Sure does kill the reloading option. I think the ridges impart longitudinal strength to the case, which makes it act like the brass is harder. It looks and acts just like reamer chatter marks. 14 of 250 cases had this. Another 4 had other problems. I tossed all those. From now on, I'm buying new brass only.