I have heard that theory before. Not sure if it is true or not. I could see some problems maybe. Say a .22-250 with a 1:7 twist, and shooting a 35 grain Berger at well over 4000 FPS, I could see that causing the thin jacket to have some problems before it gets to the end of the bore. That is a lot of force onto a small projectile. Thats the only thing I could think of, actually causing damage to the bullet, which might cause it to be unstable???