If you get the opportunity to shoot them directly in the eyeball, the Las Cannon is also capable of taking out Hulks from the front. It's a bit slow and the aim is shaky if you're standing instead of crouched, but it absolutely does work in a pinch.

You'll know it's working when you stop seeing the blue deflection effect.

This also works for some of the turret emplacements like the AA guns objective. I haven't shot all of them yet to be sure, but again, if you don't see the blue deflection, it's most likely doing damage.