Abstract: In the representative embodiments of the several methods and apparatus of the invention disclosed herein, a movable detonating member is arranged to be selectively impelled against an impact-responsive detonator on a well bore perforator having one or more explosive devices. The movable detonating member is initially restrained from moving in relation of the tool body by a heat-responsive material which, in one embodiment, is operative to release the detonating member when an electrical heater on the tool is initiated from the surface for melting the bonding material or, in another embodiment, releases the detonating member when the material melted by elevated well bore temperatures.