Ian over at Forgotten Weapons, takes a look at a M3 Carbine kit going up for auction through Rock Island Auctions later this December.
Weighing in at a stout 30+ lbs and an effective range of 75-100 yards does not make this that amazing compared to modern technology. However this was made back in the 40s and was used by the US military in WWII. At that time, this was an effective weapon. It uses a 6v battery backpack that has a transformer that ups the voltage to 20,000 volts. It can be mounted to any M1 carbine. In this auction it is installed on an Inland M1 Carbine.
For those interested in owning this piece of history, go to rock island auctions.