It fires an 18kg metal slug up to 9000km/h from New York to Philadelphia, slamming into its target with 32 times the force of a "one-ton car being thrust at 100mph (160km/h)". Railguns aren't sci-fi anymore.
We'd seen experimental lab models of a railgun weapon that were impressive enough -- but they were just that: lab models. Enormous, room-filling contraptions that looked nothing like something you'd see on the deck of a destroyer. But for the first time, the Navy says it's successfully tested a fully weaponised railgun built by BAE, a private weapons firm. "It finally looks like a gun," the Navy told us. And they're right.
The plan is to continue testing over the next five years, ramping up the energy level to 32 megajoules and beyond. How to power such an extraordinary gun is another question entirely, however. The Navy is hoping for an ambitious rate of 10 rounds per minute, but at the moment, there's nothing in our fleet that could deliver that kind of juice. Batteries "similar to [those used in] hybrid cars" seem to be the best option, but batteries run out. And you don't want to run out of batteries in the middle of a naval battle. The Navy also doesn't seem to have a clue how it'll use the railgun as an anti-missile system -- one of its stated plans.
Between budget cuts and engineering hoops, the day a railgun sees real action on the seas is probably very far away -- and besides, we don't have any enemies to use it against beyond spooky Cold War ghosts. But the the destructive spectacle the railgun represents, and the tremendous leap beyond the kind of guns we've been using for almost a century now, is profound.