well, not to be the SArse i normally am, but as i begin to follow in skid's footsteps, as he is my HERO...
uh, is al gore's invention inoperative in your location of 'planet earth'? as my commodore pet located 12.9M in .038 seconds but one article on history and instructions on how to build one, w/youtube directions for the reading impaired, in, oh, let's see...milliseconds??
and while i know you didn't ask for further comment, there are several tactical concerns regarding using something so self constructed to use probably with the bad guy close or even at a distance, the first comes to mind is ability to adequately aim and maintain control over the firearm is really questionable IMHO.