Abstract: A Child Proof Key for Barrel-housed Gun Lock is disclosed. Also disclosed object of the present invention to provide a Child Proof Key for Barrel-housed Gun Lock. The lock includes a handle defined by a slot formed along its length for acceptance of the shaft. The shaft is hinged at one end which permits the shaft to be stowed within the shaft slot. The shaft terminates in a key socket at its head for engagement with the keyed head of a bore-housed gun lock. The key further includes a bushing along the length of the shaft for centering the key socket within the barrel of the weapon, and further to identify the size by indicia inscribable thereon (or other desirable indicia). Very importantly, the shaft slot formed in the handle is defined by a shoulder and a shaft bore, with the gap between the two shoulders being slightly smaller than the diameter of the shaft such that the shaft snaps into the slot when stowed.