I feel that it's too expensive for the job it does. Artillery will ramp up so long as the enemy is in sight.
I think this is no more than a super expensive 'force retreat' button. It's inferior to sector artillery (which is cheaper) and will only do some damage if your opponent is stupid enough to sit around to watch the fireworks. It also takes around 10 seconds to hit so plenty of time to reverse your tanks 10ft or retreat your weapon teams, hell you could even walk them out of the way as it's a fairly small radius for the price.
At 300 munitions it's way overpriced. To fix I suggest lowering to 200/220; alternatively make it sector artillery without the smoke and still require sight.