How do you beat sucker on sniper assassin 2?

The level "sucker" is mission 9 of Sniper Assassin 2. You have to shoot the two tiny guys that walk out the door at left when the helicopter lands. Your own copter will move away in a few seconds, so you have maybe two shots at the first guy and three at the second (you can hit him as you pan away).

Try to keep your aim steady just as the door opens, because they will both walk the same path. (If you can beat this once, you will find it gets much easier!)