Okay, this is just a fairly well educated guess here but I believe the water jug tests on these "X Series" bullets will be a little faulty. Reason being is the hollow cavity. After opening, that hollow cavity will function as a "brake" in fluid dynamics. When it hits an animal, I'd have to imagine that cavity will fill up with material before it really hit "fluidic space" allowing greater penetration with those razor sharp petals. With a pure water test such as this that cavity will fill with water and then you have the surface tension of not only the target water but the surface tension of the water contained in the cavity.