Sometimes, to effect the desired placement (ie, get the bullet to the place you want it), it's necessary to drive the bullet through a significant mass of intervening tissue. The general consensus of opinion is, that can be easier to do with a bigger bullet.Myu guess would be, there's a certain benefit too, to be realized by the increased impact dynamics of a larger projectile. Think about the difference in being whacked over the head with a wooden baseball bat as opposed to a broom handle going twice as fast. Just speculating, of course, I've managed to overcome the temptation to do any actual research into the matter.
