I recently changed inserts in my ball.  Previous inserts were the type with the flat edge on the bottom, and the new inserts are just plain oval.

I didn't have a lot of revs to begin with, and now with the new inserts I think I am getting even less!  It's hard to say for sure because I've only thrown 3 games with the new inserts, and my league conditions are never consistent (sometimes the backends are really crisp, sometimes the middle is oily and the outside is toast, or vice versa), but I really had trouble getting my fingers into the ball.

The new inserts feel much better (old inserts always felt a little tight, or would start to hurt my finger tips after a few games), but they also feel bigger.  Sizes are the same, but the new inserts feel much bigger (not too big for my fingers, but they aren't tight like before - I actually didn't feel any pain in my fingers after bowling this week).

I'm just wondering if anybody has experienced anything similar, or if maybe this is something that will take a little while to get used too?  I almost switched balls (to a ball with the old type inserts) because it just looked like my ball was rolling almost straight down the lane, and I just couldn't seem to get any rotation.