As has been said on this thread:
Energy is a poor indicator of killing power.
The key is to punch about a 1/2" or larger hole through vital plumbing.
With spitzer type bullets, penetration is remarkably constant over a pretty broad operating range. If impact speed is in that range, it does not matter whether the bullet came from a 30-30 or a 300 RUM, the result will be essentially the same.
Most standard cup and core bullets need at least 2100 FPS at impact, and no more than 2800 FPS at impact. Partitions, for example, open at 1800 FPS and make about the same length wound channel to over 3200 FPS. Pay attention to keeping your bullet's impact speed within its design range, and you'll get pretty uniform results.
Use a standard bullet for a close in shot at 3000 FPS, and you're begging for problems.
More muzzle velocity does not get you deader critters. It gets you a longer, flatter trajectory.
