How should my index finger be on my spike curve?

i pretty much know how to grip a knuckle curve and what to do. snap the ball down with the middle finger and and flick your index forward but on one website it showed the index bent back and the nail dug inside. i thought you just bent it back. are used sussposed to have your nail in

Well it really depends on what you are trying to throw, I throw a knuckle curve with a 2 knuckle grip and throw it like a fastball letting my fingers give the forward spin on the ball, the knuckle curve you are talking about I call a spike curve and it sounds right.

I used to throw my knuckle-curve with both a two-finger and a three-finger grip, and I found that this would affect how the pitch would break and that with the three-finger grip I could get a nice changeup. The wrist action was the same for both—the karate-chop wrist snap. :slight_smile:

I don’t even snap my wrist, just push my fingers forward and let it go like a fastball, I get a nice break.