Railguns are limited only by rail/projectile durability, rail length and the amount of juice you pump into it. The first is already considered pretty near as good as it gets, but it being obtained so early in the game effectively pigeon holes the weapon type's effectiveness, at least from a lore perspective. Another railgun won't suddenly be sporting a far superior battery and unobtanium rails because the current weapon is already near capped development-wise. How would you explain the new weapon's jump in ability?
But then again, ww2 era myrellion already gives trench weapons that beat out current tech, so who knows. I only mentioned this because Fenco seems to be attempting to maintain a somewhat consistent lore. If not, then everyone will get their super death rays, anti-matter planet destroying wave-motion cannons and so on, and then it will all be rendered completely useless by whatever comes next.
Weapon progression is rarely an issue with olden day era rpgs, since a sword's a sword's a sword. However, scifi also has technological progression which really shouldn't go backwards in effectiveness (barring exceptions). Otherwise you get a post game pebble that beats out nukes in power.
tl;dr: "This thing is awesome and I want more because I want more" is a terrible approach imo.