The achievement isn't difficulty specific, so can be done in casual if you struggle with higher difficulties. Overall a not too difficult achievement if you take your time, slowly working your way through the level.
There are however a couple of sections that could potentially give you trouble. In the first vehicle section, try to use explosive objects to kill the enemies faster. Also, later in the level when you are using the turret whilst the elevator is being called, sweep back and forth taking out the exploding enemies as quickly as you can. The less that blow up in your face the better.