User blog comment:Midnightpiranha/Another Mass 3 MP DLC pack idea/@comment-66.31.178.224-20120812161500/@comment-81.14.35.74-20120820155959

What is implied about most of the weapons is the slugs are magnetic in themselves or partially ferrous so you can just throw them into a magnetic field, the slug in a rail gun is conductive but not necessarily magnetic itself. That is the crux of the difference but you are correct in that it uses magnetic forces to accelerate the bullet, but it uses Lorentz forces rather than attraction/repulsion.