I am actually not focused on energy. I am simply making a point. What concerns me is the amount of it that can be used effectively and that has an awful lot to do with bullet construction, yet another variable, and what we consider effective for a given task.
I am going to make up numbers here just to illustrate my point.
Lets say we have 2 cartridges. 1 has 500 ftlbs and uses 400 of those effectively to create damage. 2 has 800 ftlbs and uses 500 of those effectively to create damage. Assuming that damage is done to equivalent areas of the target, cartridges 2 is less efficient but more effective.
On the other hand, if cartridge 3 has 600 ftlbs and uses 300 of those effectively, it will be less effective than cartridge 1.
Again, I am not talking about energy being dumped into the target. I am talking about energy being effectively used to create damage. In all cases, energy is a limiting factor. You can't do X amount of damage without at least X amount of energy to work with.
The application is much more complex with many variables but the basic concept is simple.
Energy = potential
energy used effectively = damage
bigger bullets = usually use more of their energy effectively
Obviously, none of this takes into account many other highly important variables like accuracy, rate of fire, ability to recognize the threat, ability to draw and get on target quickly, the nerve to do what is necessary, accounting for innocents who could be in here's way... The original question was velocity vs energy and the obvious answer is energy. They actually can be separated for the sake of argument, particularly when comparing multiple calibers. Given the same bullet however, no they couldn't.
An example would be comparing the 5.7x28 to a 40. The 5.7 has a lot more velocity but less energy. Right or wrong, that is how I interpreted the original question.
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