I was wondering if anyone knows anything about 9mm drill ammunition? I have a 9mm round with the following headstamp: RG 53 9MM D2. I’ve seen similar on ebay described as drill rounds and assume that’s what the D2 means. The cartridge has three small indents pressed in at 60 degree spacing and it doesn’t appear to have a primer. The whole thing looks like it once had a bright silver plating. Does drill mean inert?