Gun Control: The railgun [top] gets its name from its two parallel conducting rails; dc current travels up one rail and down the other, creating an intense magnetic field inside the gun’s barrel and propelling the armature and projectile. The coilgun ­[bottom] consists of one or more coils of wire, each of which is powered on and off in succession, creating a magnetic field that pushes or pulls the projectile to the next coil. The pictograms show proposed uses for electric guns.