I find magic drop is more about your NTH because your throw hand shouldn’t really move. You kind of have to flick your NTH in an angle based on which string you want to hit.
That being said, I’m convinced the only thing that will make this trick work is repetition. I’ve been working on Magic Drop for over 2 weeks. Some nights I’ve spent 1-2 hours just doing that trick alone. I can get it just about every time now, but my advice is put on a movie and just keep doing it over and over. Brandon Vu probably has the best tutorial on it.