To destroy stuff like shielded turrets, just run into them with a scout and they will blow up!
Fun with Teammates
If you want an interesting way to badly maim or kill your own team, then I suggest using one of the tips below.
In Raindance, get into the large Rocket Turret in front of your base. Wait until someone gets in a scout(works best) or any other vehicle. Hit them once as it appears on the vehicle pad then as they hit the throttle to full speed to try to get away hit them again. If done right, the scout or other vehicle will explode and they will continue "flying" which is good if you are getting bored.
Although I warn you, after a couple minutes of doing this, the team will come after you! But it is still hilarious to watch the little green arrow pointing to your teammate flying into the distance.