just my 2cents here. I have a problem with my fit only during the spring. i use a extra smooth blue thumb tape and that helps, but like everyone else i was having a problem with thumb and finger callouses. it was getting so bad it hurt to bowl, on the outside back of my thumb and last knuckle on my fingers. it hurt to throw the first ball, but then as the night went on it seemed to get better. i talked to my proshop guy, who i trust completely, and he mentioned that in the spring i start working more with my hands and thus my hand "muscles" up and shrinks my span for when i bowl. then as i start to bowl the hand stretches and the span gets better, and the tightness in the inserts then dissapates. not because my fingers shrink, the hand actual gets bigger, helping in the fit. He had me start stretching out my hand before i bowl, and the pain went away. i do still wear the tape, but just by stretching my hand out first, the fit of the ball starts out the night right.
again, this is just my experience, and it is not intended to be the cure all for everyone else.
