I would love to be able to see an actual artillery tank on the battlefield. However, railguns have inherently greater range than artillery will ever have and more accuracy to boot. (Modern US test Railguns can hit a shed over 5 miles/8 KM) However, artillery has the ability to arc shots over terrain, buildings, and friendlies. It would also make the Missile Turret skill a bit more balanced, since right now the Hybrid Turret skill controls a long and short range set of turrets. It could also come in different variants, such as fragmentation for anti-personnel and HEAT for anti-armor. As for naming, you could change "Hybrid Turret" to "EM Hybrid Turret", since both rails and blasters use EM acceleration, to lessen the confusion between chemically accelerated, or exploding hybrid turrets and electromagnetic hybrid turrets.

Keep it Eve style, rail range > arty range

Have you played eve?
maybe I'm missing something, but last I checked, arty range was longest

I think it would be cool if there was a module infantry could carry that would send coordinates to any tanker using the Artillery turret. The targeting system would show a large reticule with an altimeter, and holding the reticule in place for a second or two would create a trajectory path of your round (This would be to discourage perfectly accurate hip firing essentially). If an infantry player used the targeting module, TACNET would display "A new target has been acquired" across the screen. This time, the trajectory path that would hit the target set by infantry would already be in place, and tankers would have to line their shots.