Heh, cute little feller. I rather like the Grenadier model, but it seems far too specialized for my liking. Interesting jack you have here; might i recommend using a ruler when doing the stream of gunfire as well as increasing the flow of casings from the side. Also, you should put them in a higher arc, cos falling diagonally to the ground robs it of a sense of force.
Thanks for the comment, the drawing was made entirely with free-hand when I was doodling at the park. The standard Charger chasis isn't really to my liking so I would like to make all the light jacks from grenadier or hunter chasis.