I don't think you need to register them, but for me to acquire them through sale or say a last will and testament, I would have to have a PAL or they would go to auction. Same with to buy ammunition for a gun, I think you can buy the casings without a PAL but the bullets or gun powder I think you need a PAL or they aren't allowed to sell it to you. They also keep records of who buys what type of projectiles and powder based on the PAL number for enforcement and tracking purposes.