Coilguns were declared a dead-end and never mass-produced, the cost of their construction for such a minor advantage over normal fire-arms, coupled with the extreme stress put on the gun (and subsequent cost of repairs) meant that they were useless as small-arms. Thing is, weapons tech never advanced much, as the weapons themselves never got much deadlier, or at least not enough to justify the massive spike in price. There might be prototype Gauss weaponry available somewhere, but it is extremely rare tech.