Initially, I thought they were Master 9mm Luger cases; beautifully nickel-plated. On closer inspection, the headstamp was “A-MERC (over) 9mm”. Like “MASTER (over) 9mm” -headstamped cases, the flash hole was deburred – indicating manufacture by Starline. Previously, I pretty well ignored A-MERC, noting only indeterminate-origin “9MM” cases. I’ll have to inspect A-MERC cases more closely in the future.