It is doable very easily during the first mission.
Close to the end of the mission you will control a turret on an armoured vehicule driven by the AI (rail gun shooter sequence). At the end of the sequence the vehicule will be stucked and you will be surrounded by dozen of enemies : just fire in the middle of the swarm and you will pop it up !!
Advice from blueriversbeast
: Just spam LT and RT at these points !