I would agree that your principles in the above quote and statement are correct. But if that bullet never leaves the body it doesn't matter how fast or how much it expanded you only have one hole. A hole that will likely be the same or slightly smaller than the caliber of bullet used. (I know there may be the occasional exception where by some freaky physics a "splash" wound appears at the entrance) You are correct, generally, greater velocity=greater expansion=greater wound channel=greater hole. IF THE BULLET LEAVES THE BODY I believe this is what makes the sub-calibers so viable.