FYI: Found and photographed a .400-3inch case which sustained dents on first firing. It was about half-way through a series of 10 shots with new brass. This is only the second time it has happened to me personally, and I've been shown it by other reloaders a couple more times over the years. As you can see, it's quite different from the small dents on the actual shoulder caused by excess lube in the sizing die!

Anyone else had this happen?