A rail gun is a weapon the uses electromagnetism to fire a projectile, rather than gunpowder. The advantages of such a weapons are numerous and significant. First, with far fewer moving parts, there is less chance that the gun shall jam, and, in theory, it could have a far faster firing rate than a gunpowder firearm, if the technology were sufficiently advanced. Second, with no ignition of gunpowder, a rail gun generates less noise, heat, and recoil than a traditional firearm (obviously, there will still be some noise, heat, and recoil, due to the laws of physics, but they shall not be as great as those in a gunpowder firearm). Third, the velocity, and thus force, of a projectile fired by a rail gun can potentially be far greater than that of a bullet from a gunpowder firearm, and, even better, the velocity can be adjusted to suit the needs of the user.
Of course, there are some problems with rail guns, however. First, the amount of electric voltage and current required to power them is so great that they are not yet feasible as commonplace weapons. Second, they are very large, and thus can fit on only massive vehicles, again limiting their use as handheld or otherwise portable weapons. Third, they still are very expensive, but that, plus the first two problems, may eventually be solved as time passes and the technology improves.
What does everyone else say about this? Will rail guns ever replace gunpowder firearms?