Originally Posted by Topgun 30-06
The bullet carries energy in several forms
- just from velocity E = 1/2 MV x V
- Rotational energy from spinning - I won't write the formula
There are several ways that an animal dies from being shot in the chest:
- Bleeding to death from severing an artery or vein (thing bow hunting or similar bullet damage)
- Energy "shock", similar to being beaten with a really big baseball bat
If your shot is very carefully placed, then the animal will bleed to death no matter what, but it might take a while.
If the bullet goes all the way through, that makes two holes instead of one, so bleeding is faster, and likely there is more internal damage. At the same time, the remaining energy of the bullet was "wasted", as it didn't provide any "shock" effect. Sometimes this matters, some times it doesn't.
If the bullet "expands", this is an indication that the bullet transferred some of the velocity energy it contained to the "shock" aspect. If a bullet is too hard for the application, then it will not expand at lower velocities. Depending on what the bullet hits inside, the rotational energy still may or may not be transferred efficiently.
At 400 yards, a 270 shooting a 130 grain bullet has slowed down considerably compared to its 200 yard velocity. The hornady web site shows their projected velocities at various distances, so this can provide an "indicator" of whether or not a specific setup will work or not for proper expansion.
A lot of bullets on the market will not fully expand if the velocity is under 2 000 FPS. Some Barnes solids (example dangerous game versions ) are designed to hardly expand at all.
CEP (and some others out there) are designed so that the nose breaks up into little cutters (causing both bleeding and shock energy transfer) while the bullet base continues on for the exit wound. The cutters breaking off and continuing with their own damage is one method to improve transfer of the rotational energy to the animal as "shock".
CEP claims (and I have not verified this) that their Raptor ER bullets will expand / break into those cutters at 1 500 - 1 600 FPS rather than the 2 000 FPS a normal bullet needs to expand, and the improve BC will help reduce velocity loss at long distances than a normal RN bullet. At 400 yards, this might make a difference.
Matrix uses the same concept, just in a lead core version.
If you think about this, it is no different than any other bullet selection discussion, longer range shots need more care put into bullet BC and expansion than short range shots.