Feli sent over this link to a custom launcher called the PEST. It’s Airsoft but not quite what you’d think, however it’d take 8mm BBs as is. It’s electromechanical, but looks to use a very cunning centrifugal launching mechanism. It’s a pretty cunning idea actually. Checkout http://www.geocities.com/pest3125 for more info:
This website provides information on a a portable, battery powered, electromechanical projectile launcher the author designed and built. It is a type of “centrifugal” launcher powered by a DC motor. The launcher fires primarily plastic spheres (or steel with some modifications) semi- or full- automatically that is more powerful than a typical airsoft gun. No compressed air or any other energy source besides the battery pack is needed to power the launcher, so it is capable of sustained full automatic fire. The device is called a “PEST”, or Portable Electromechanical Slug Thrower for short. PEST3125, (PEST3125’s Projects)