This ability has gone through many nerf and its in good place now and even locked behind the forward hq in the commander.
However, the shell's speed was reduced to a level where they can't hit anything, youre own tanks are more likely to be hit by them since they has this big delay.
Remember, the shells only do 40 dammage and are more supose to stun tanks rather than do dammage while activated.
It's not even near as effective as the overwatch anti tank ability, but good use to make tanks retreat if its in the area.
solution: Revert back the speed of the shells so it can hit something. It was same as the Overwatch tank shells speed before it was nerfed.