They didn't his anything 100 miles away. Why? Because they can't. Ordinary rifle bullets already travel as fast as this railgun's projectiles. There's a whole lot of "could" in that article.

It's all neat and sci-fi looking, but it's not a real weapon, and probably won't ever be. This is a huge waste of money-- $211 million in the past five years. The article reads like "please don't cut our funding" hype, a lot like what NASA's been doing lately.