I dont understand why people are finding it hard to kill the BD's. Simple way is to shoot proximity mines AT the big daddy, not infront of him - they explode on impact! You can fire them so fast hes dead in a few seconds. If you run out of mines, grenades work exactly the same. If that fails fire a mine at a gas tank and telekinesis it into him 
If that fails I would fire a couple of traps from the crossbow infront of him as that really hurts. Ive got the achieve for "dealing" with all the little sisters now
And the one for saving every one. I thought the story sucked the first time I played it but when I played it the second time I understood it a lot better and Im using many different tactics now.

If that fails I would fire a couple of traps from the crossbow infront of him as that really hurts. Ive got the achieve for "dealing" with all the little sisters now
