This is an extremely hard shot to pull off for you to get three stars. Aim directly at the machine that swings the TNT bomb. Timing is key to get this stage, your contact point is when the machine is swinging the up the bomb. Another key is not to pull the slingshot all the way, let loose a little bit so that your bird would only touch the bomb.
Power Activation Point
Activate the power as you are about to land into the bomb. You want to break the joint while the bomb is on the swing.
First Shot Result
The bomb gets swung into the car, killing all the pigs in the vehicle to give you the three star rating. However, this stage is extremely hard to pull off with just 1 single shot.