Velocity vs. Energy

[PegLeg45]

I like factual data, coming from actual usage when ever possible, but a lot of that data, does not apply to the occasional 400 lb bad guy, 8 - 10" of penetration is great for most SD efforts, but this guy needs up to 18".

+1

In a SD situation, you don't get to choose the target ahead of time. It could be a 150lb crack addict, or a as M25 said a 400lb guy.
All you can do is test, practice, train, plan, test some more, and try to be as ready as possible if the time comes.

[tombogan03884]

I only have a fuzzy understanding of  "Bullet Energy" I just work on the principle's that
1- Bigger holes bleed faster
2- If one is good 14 are better\
3 - Placement rules them both

The way I understand it all the damage a bullet does besides the hole, is caused by the transfer of the  (Bullet weight  and velocity ) into the surrounding tissue This energy dump is aided by expanding bullets since they present a larger frontal  area creating a greater amount of drag.  (and a bigger hole )
My conclusion comes simply from thinking about it not any math, but it seems to me that while you need enough penetration to reach vital organs, but if your bullet goes clean through then you have wasted that energy and would be better served by a heavier bullet on the same powder charge.

[nupe]

Like m25 was saying the equations for kinetic energy (energy of a body of mass in mostion) is (1/2)mass*velocity².  In other words a 9mm can have roughly the same energy as a .45acp (both right around 350-360 ft*lbs), but it really just depends on the bulllet type.