From the Star Wars: Battlefront Wikia.
The Clone Sharpshooter is the sniper unit for the Republic. Used to pick off enemies from long-range, their gun has a 2x and 8x feature which allows you to view the enemy quite closely. Generally you will have to aim ahead of the enemy unit to make sure you hit it. Always aim for the head, otherwise, you will give away your position to the enemy and he can easily evade you or find cover, preventing you from killing/destroying him. In Battlefront II, the Clone Sharpshooter and his fellow sniper classes do not get a targeting reticle when not zoomed in-- but this is no hindrance to experienced players, who become quite good at 'shooting from the hip.' An effective combo is to fire the rifle at a unit to clear away most of his health, then switch to the pistol and fire rapidly to finish him. (Equivalent- Assassin Droid, Rebel Marksman, Scout Trooper) This unit, along with the equivelant units, carries grenades and an auto turret.
[edit] Attacks