If the bullet is large enough to begin with, expansion is just icing on the cake. No?
I realize this has little or nothing to do with this discussion, but I would opine that shape and size of frontal area of expanding/expanded projectile matter more (along with speed of moving projectile) than does the diameter of the original bullet. Of course the original diameter may affect those details.
I always thought this was true. Still do.
Royce, experience with charging grizzlies does not come cheap for most of us; nor frequently. But the issue sure does get a lot of ink