One other factor that I haven't seen discussed here is the rate of decelleration. If you have 2 bullets of equal weight and delivering the same energy at the same range, fired from the same gun, one a hollow point and the other a fmj. the hollow point will decellerate much faster (assuming that it mushrooms and does not fragment) and deliver its energy in a much shorter time perioid. This will "whap" the target much harder than the more gradual decelleration of deeper penetration. Furthermore, if you get full pass-through penetration, the massXvelocity of the exiting projectile is not delivered to the animal.

I'm not sure exactly how the 12 ga slug measures in this way, but I do know that they "hit" about as hard as any projectile of their mass and velocity could.

What I'm trying to say is that there are several aspects to the equation of stopping any animal -- Total energy delivered, the rate that that energy is delivered, any vital organs hit, WHICH vital organ hit, super-sonic shock wave, the attitude of the animal when hit, how much adrenaline kicks in, whether or not bones are broken and mobility is disabled, and I'm sure there are several others that we haven't discussed yet. There has been a LOT of good tecnical data delivered here. I think most of us have a valid argument, at least to some degree. Personally, I would want the most massive projectile I could get, travelling at the highest velocity possible, that decellerates the quickest, and placed in an essential spot necessary for mobility, delivered from a weapon that cycles VERY quickly with a recoil that allows for quick reacquisition. My pick -- a .50 Beowolf or a .45-70 either in the brain or clipping the spine.