1. Go to Level #5 in the Easy category
2. Move into the corner closest to the starting point, face forward.
3. Tap the strafe left key twice (default = A)
4. Aim here (enlarge photo to see crosshair placement)
5. Shoot

This setup seems fairly consistent, but slight variations in aim, angle, and how long the strafe key is pressed will affect your position.

It is possible the pillars will fall over but a couple boxes on the bottom won't be "activated". You can just walk into these to activate them without firing another shot.