On Vendetta when you get to the part where Amsel is, kill the sniper then shoot him through the tank.

Let him get to to burning truck, shoot him through that - do not shoot his legs though.

Wait for Amsel to get in the car and kill the driver and make sure the car stops at a spot where you can shoot the door.

Switch to your pistol and shoot Amsel through the door before he gets out.

Achievement unlocked!

Note: the pistol is located on tables in the room where you have to kill the sniper near the beginning of the level.