Register any existing weapon serial in your server, and retrive them!
Weapon Dealer: The book will check if serial in input is bind to any weapon inside the Db (weapon/armory script), if so will add the serial to a new table with the name of the customer.
Sheriff/police: Can search for a wepon serial and retrive the name of the owner!
Note: you should have a weapon script that generate a unique serial for each sold weapon