Couldn't figure a better place to ask this than to ask the reloading crowd.
Guy in the shop today said something that I totally disagree with even though I actually have no reference to prove it.
He, for whatever reason, decided to spout out that ".40sw is the same size as a 9mm".
I pulled both rounds from the ammo cabinet and proceeded to compare. Hmmmm. . . . . . the 40sw sure looks a good bit larger than 9mm to me.