I'm really weak at this one, I barely could know where enemies go or aiming somewhere. And I would just instantly die. I really need to improve this, so does anyone have an idea?

Pistols, Shotguns, Operators, are all useless on these crabs. The crabs are indestructible and impervious to all damage. These little blue bois should pop like balloons on impact. Solid 11/10 feature right here. Thoughts?