The Mass Driver is a pretty classic sniper rifle.
It features a very long barrel for precision and skilled shots at a very long range.
Every bullet consumes a lot of energy, though, so you have to aim carefully, looking for a clear shot. Its armour piercing bullets can deal a lot of damage and a couple of hit can almost destroy every spaceship in the game.
You can keep pressed the special weapon trigger and look for the tiny crosshair that is going to show you where the bullet will hit.