I have a bit of a tip for practicers of this move. Instead of trying to do the spin holding it on the pad of the right middle finger, try to hold the corner more toward the first joint of the finger, about a quarter to a half an inch from the pad of the finger. That way, the card spins on a harder surface (the joint) than on a soft one (the pad). Also, pull the cards more to your left with your left thumb so that it's further out from the deck, giving it more freedom to spin. And, like everyone's said... loosen the pressure. It should be held almost to the point where you feel like you're dropping the cards.