Killing all of the targets with headshot earns you a 1.09 point modifier.
This Challenge vies for the most difficult and challenging of the lot with the Fly By one – though for my money this one is the more difficult in that you have to shoot every single target in the head. That means you have to shoot all of the targets, without any alarm being sounded that causes them to evacuate, and you have to hit them all in the head. Within the time limit!
Strategically this really requires you to shoot the targets with an emphasis towards them ending up either going over the edge of the building or their body falling into a hidden place – like the lift shaft or one of the water garden runs. The more of them you can take out with their body concealed the better as that lessons the chance of an alarm being sounded, and increases the chance you will actually manage to pull this off.
That being the case what I suggest is that you do the following – and remember this is a matter of timing as much as it is accuracy!
You should be able to manage this inside the timer with a couple of minutes to spare!
Watch the video embedded above if you have trouble with this one!