In full context, what I wrote was "If you have a particular bullet and want to insist its velocity matters, only then are you correct because you are also talking about a particular mass as well as velocity - i.e. energy."
Energy = 1/2 * m * v * v
Or maybe if you're talking about velocity you're just using it as an indicator to make sure you're operating within the design parameters of the bullet for maximum wounding. You know, that stuff Formidilosus keeps bringing up. But what does he know?
Too slow and the bullet doesn't open. Too fast and it disintegrates and doesn't penetrate into the vitals. Pretty simple stuff really and no equations needed to understand it.
