A railgun is a staple science fiction weapon. Unlike guns that use a small explosive charge, or compressed gas, to accelerate a projectile, a series of electromagnets in a railgun's 'barrel' act on a projectile, one after another. As the projectile reaches each electromagnet, it shuts off and the next one is turned on sequentially. Theoretically, very high muzzle velocities should be possible. This isn't a new idea. A 1933 patent application describes a machine gun that uses magnetic flux instead of "gun powder or the like." We don't have electric machine guns today quite likely because back in 1933 we didn't have high-output portable generators. Mr. Virgil Rigsby of San Augustine, Texas went for the small-scale version of what today is known as a "railgun" when he patented his electric machinegun, which would have revolutionized warfare if the extension cord had stretched a bit further...." It failed because it was not practical- the power supply being a heavy generator to transport and an easy target to take out on land or by air. By 1945 at Peenemunde, von Braun and his scientists had looked at various projectile shapes for future cannon and missiles and so the idea came around for a new rail gun in 150mm caliber by 9/44 that would be installed in a massive bunker with its power source buried in a mountain or under up to 36 ft of reinforced concrete able to withstand anything the Allies might throw at it. The Germans also had a small scale 40mm Electric Gun by Hansler and the V-3 multi-barreled cannon. Postwar, this weapon was debated and then as technology advanced the US Navy has wanted it as replacement for the old battleship big guns (also unrealistic, even with nuclear reactor derived power)!!!

http://davidszondy.com/future/war/railgun03.jpg http://blog.modernmechanix.com/mags/ModernMechanix/9-1934/rail_gun.jpg