1kJ Homemade Railgun

I have made a picture and caption instructable of how to make this: https://www.instructables.com/id/How-to-make-Homemade-Railgun/

This is a 1kJ railgun that I made for my high school science fair project, using a 15600uF capacitor bank. I wanted to determine what proportion of the energy in the capacitors was actually converted to kinetic energy (it turns out not much if any).