Wow that's amazing I always love reading about EM rail-guns in sci-fi novels it's great (and terrible) to think of them becoming a reality.
I wonder if this is how the knights of Europe felt when they saw the first cannons.
Nerd rant alert:
Spoiler:
Although they're being misleading about the cost. The cost of firing them isn't just the ammo it's the energy required to generate that powerful magnetic field. Plus the big downside of rail guns is that constantly exposing the parts to powerful magnetic fields causes them to warp and twist making maintenance a real bitch. At least thats the theory of EM railguns it's never been a real thing until now.