No, that is not a headspace problem. The cause is internal case erosion by the acid in powder that has not been properly washed, usually during speeded up wartime manufacture. It is seen on ammunition from all countries (including the U.S.) and with all case materials.
It may show up on the side, neck or near the base, depending solely on the orientation of the cartridges in long-term storage.
The cause is usually not apparent because the problem is not discovered until the cartridge is fired, at which point its initial orientation has been lost.
Jim
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