John,
I wouldn't be all that surprised that they didn't know, or at least the person who answered my question didn't know. Maybe though their response is just exactly what it says, and a hgh RPM bullet coming undone in a target is not necessarily "opening wider".
My experience with more damage from high RPM bullets causing more damage has been with high velocity in addition to high RPMs with smaller targets. That putting the bullet a lot closer to coming undone seems to matter. 14 twist vs 9 twist in .223 & 22-250 gives me the impression that velocity is much, much more critical than RPMs. The numbers and size of target sample are not huge though.
Might be an interesting experiment to take the same bullet in a 9 twist .223 and a 14 twist 22-250 and catch some in water jugs matching velocity to see what happens to the bullet.
