This is a close-up of my 'down and dirty' mechanical switch. The longer bare wire will make contact with the orange wire once it is pushed by the pellet. There is about a 1/16" gap between the two. I tried less, but the "slug" of air pushed by the pellet was closing the circuit. A couple of flashes went off, but the pellet was not to be seen. One can imagine that there is quite a rush of air in front of it. Now we are ready to go. Shut off all lights, open shutter, shoot gun, close shutter and see what you have.