Years ago the police departments of this country devised a program called operation identification.You simply took an electric engraver and put your drivers license number and abbreviation of the state that issued it on the item.Then if this item was discovered in the possession of anyone who did not possess that license it gave the police officer probable cause to hold that property, and or the person, to determine ownership.In the case of firearms you can remove the grips or butt plate and engrave that number.I was involved in this program in the Early seventies and I can still recite my drivers license without any difficulty.