Messing around this morning I came across the thread on the home page about Sierra's new "Game Changer" bullets. Having been tinkering with a 10" twist .243 Win for the last year, I was excited to see the new 90gr bullet under this offering, part #4100. I called Sierra to get more info. According to the tech I spoke with the bullet is 1.161" long. I also asked if they had a twist recommendation. His words were "we do know it will stabilize in a 10 inch twist 243." Plugging numbers into JBM's stability calculator, without tip length (tech did not have this info), the bullet looks to be marginally stable in a 10" twist. Guess I'll have to try this the old fashioned way and buy some to find out!!