With the 12 O'clock, or 10 degree bowling hand position, as you are holding your ball your thumb comes straight up with no (or very little) side turn. Your hand and thumb will be at the 12 O'clock position as it is released.
This release will give the bowling ball a lot of end over end roll. It causes the bowling ball to delay its break point. This release is used on dryer lanes and to help get the ball down the lane before it hooks. In addtion, the ball motion will have less change in direction in the hook phase (Note: this is also called a 10 degree axis rotation) a common term used by many bowlers for this hand position is - (stay up the back of the ball or stay behind the ball).
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