Can you please adjust range damage and special effect modifiers a bit so that each heavy weapon type is useful for some purpose?
The problem currently is that Rail-gun trumps all as it has the same range, the highest damage, and it does not loose efficiency over distance
Another problem is more esthetic: I just happen to enjoy many of the other heavy and medium weapons art on the heavy mount much better (Ion Cannon and Distruptor batteries with three barrels on capital ship would look awesome) but currently, using them is just a poor tactical choice
Maybe it would be logical to keep the long range of the heavy weapons but reduce their damage (or at least that of the Railgun), and have medium mounts cause more damage from medium to close range
BTW: did you notice that there is no "Railgun" just "Heavy Railgun"?