Abstract: A tamper proof gun lock is provided, which consists of a double dummy cartridge adapted to be received in a firing chamber of a gun. A keeper is adapted to be inserted into a bore of a barrel of the gun. A tool is insertable into the barrel of the gun, to engage with the keeper. In a first instance, the tool can cause the keeper to connect to one portion of the double dummy cartridge, making the gun inoperable by preventing the gun from being fired. In a second instance, the tool can cause the keeper to disconnected from the one portion of the double dummy cartridge, thus allowing the keeper to be removed from the barrel and the double dummy cartridge to be removed from the firing chamber of the gun, making the gun operable to be fired.