Bottom line is, kinetic energy is necessary for the bullet to do its work, but due to the myriad of variables involved in killing effectiveness and the use of kinetic energy to deform tissue, is a poor metric of ‘killing power’. A better indicator is to simply use a bullet that can penetrate to the vitals, and make sure it impacts with enough velocity to expand properly.
I agree. KE tells you somewhat how much the bullet can do, but the size, shape, and construction of the bullet and the type of material it impacts tells you how much of that energy may put to good use. It's also not the KE at the impact that matters as much as the KE at the impact minus the KE, if any, of the exiting projectile. Also, a fair amount, I don't know how much or how to calculate it, of the kinetic energy is converted into heat energy, rather than structural damage. Logically, I think, more of that would happen with high-velocity impacts. That's just one of the factors that limits the value of relying on KE alone for hunting effectiveness. However, there does seem to be a rough correlation between KE and damage. I don't think it's a coincidence that a bullet propelled by a 30-378 Wby blows stuff up a lot more violently than a similar-typed bullet out of a .223 Win., and the former produces about 4 times as much KE as the latter.
I agree. One of the many reasons that KE is a poor metric for "killing power" is that some of that energy is converted into heat energy, sound energy, etc, and the exact amounts are non-deterministic and nearly impossible to predict.
As you correctly point out, KE is a measure of the potential of the bullet to do damage, but the correlation between KE and killing effectiveness, while existent, is minimal.
