Pivi - it would be helpful if you gave the headstamp of rounds with questions like this. If an RWS headstamp, it is almost certainly a case from a proof round. Some years ago, one of the German proof houses sold off all of the fired brass they had accumulated. Some really interesting headstamps were found in that lot, and all sorts of calibers, common and not so common, with knurled rims. Huntington Die Specialties here in California had a lot of it I think. At least a friend with RCBS (right next door) sent me a big box. Disappointingly, there were no auto pistol cases in the mixed bag he sent me. They got it from whoever they bought it from all mixed, and had to sort it. There were evidently tons of cases in the batch as sold by the proof house. I’m surprised they didn’t just sell it for its scrap value.