Once upon a time I asked a gun-shop about the 2 empty brass that comes with all new guns. I was told that it was to show that gun had been fired, and only that. A couple of days ago I read that the FBI was using a recovered bullet to identify which gun it came from by using the files the keep on new handguns sold. Evidently these rounds that are fired by manufacturer are used to keep track of guns and who they belong to. Has anyone else heard of this?