Abstract: A cylindrical key operated variable code lock provides a shell having a cylindrical inner surface and an orifice for accepting a key. The key may be generally cylindrical in shape carrying a number of lugs thereon that are rotationally variable. The drum is normally rotationally fixed relative to the shell by a plurality of locking elements. In response to the insertion of a key having a predetermined code each of the locking elements, conversely, allow the rotation of the drum relative to the shell. The locking elements may be reconfigured in response to a predetermined varying of the key code. The reconfiguration may particularly entail the turning of the unlocked drum to a predetermined position and removing the key while the locking elements are in a state allowing recoding.