thought about how to make the railgun less powerful:
Enemies that have armor somewhat like you? Health with "gates" that block damage from overfilling them. A 100 Health enemy with 20 Gates would only be able to take at most 20 damage in a single hit, so a railgun would need five hits while a gatling gun would be able to quickly dispose of them.
In fluff, could be some form of super-shock ablative armor? It'd make sense since railguns and other super high impact weapons have been deployed.