ok forward roll and more revs
obviously u have to have a decent amount of rotation on the ball, otherwise u need some side rotation to help u to carry.
i remember from one coaching video where norm duke was explaining about the momentum during swing, and he said something like, to achieve a forward roll, make sure ur starting position at an easy position, and about the weight of the ball in both hands. then the most important part is that during ur SWING, the ball doesnt turn at ALL, so theres no side momentum comming when u reach at the bottom. a good example would be norm himself, or WRW, a bad example would be TJ or Jeff Carter, what TJ does at the top of the backswing is not what u want for forward roll. so, top of the backswing cupped but not sideway, u could even try no cupping to have a similar release to norm's. stay behind the ball and let go, be nice with it.
on a side note, the best to watch is going to be obviously Chris Barnes, his wrist doesnt change much during swing, but what dictates his swing is the angle of his wrist at the beginning of the approach. when CB plays deep inside, his wrist is more towards his left, when hes playing straight, then he has a cupped but vertical position.
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When a house bowler misses the mark, misses the break point and strike, for many ppl its called a wallshot. When a pro does that its call adjustment
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When a house bowler gets his finger stuck in the ball and fall on the lanes, for many ppl its called lame bowler. When a pro does that its called the Machuga flop! ha i like this one.