This is a pretty straight forward shot. Aim at the first metal block tower.
Power Activation Point
Shoot your laser gun straight forward, your gun and pig should both land on the metal tower.
First Shot Result
The flying pieces will pull the magnet to the other side. Sucking the metal tower on the other side, and the magnet falls to destroy the rest of the birds, you will obtain your three star mastery. It should note that your magnet will have to kill enough metal pieces, if you do not have enough points, just try again.