Anyway, since theweaselking made a post on firearm safety, I had an idea. We could integrate a bore-sighted solid-state IR sensor (perhaps on an external rail, or perhaps in the chamber behind the firing pin hole in the breech face?), connected to a solenoid, with a small battery in the circuit. The IR sensor would be calibrated to change outputs when aimed at something 35 degrees C or more. When the user pulls the trigger, a switch would send current to a transistor with input from the sensor. If the barrel is aimed at anything near body temperature, the solenoid would not activate. If the barrel is aimed at something cooler than body temperature, like a paper target or a zombie, the solenoid would activate, retracting a safety pin and allowing the gun to fire.