This post is not intended to start WWIII or to try and convert anyone from using the type of bullet they like but I've seen physics misquoted and used in a way not relevant to the applied physics of terminal ballistics.

First off you need to start by understanding the Law of Conservation of Energy which states That " Energy cannot be created or destroyed but only transferred".

This post is primarily concerned with the difference of using expanding jacketed ammo as opposed to hard cast. The first thing to consider is whether or not the jacketed bullet used is proper for the application, in other words will it expand as it's supposed to at the impact velocity and yet maintain enough wait for penetration. I've read the term energy "dump" and that is a slang phrase which has no real meaning. As for the law of conservation this is where it comes into play. Pulling the trigger on a firearm starts a sequence of events that all pertain to and are governed by this law.

First is the fact that you are transferring energy from your finger to the trigger, this allows the stored energy in the hammer spring to release and allows the hammer to strike the primer. All of the above are examples of mechanical transfer of energy.

Second, once the primer is struck the chemical energy stored in it converts to heat which ignites the powder (also chemical) and then transfers it's energy to the bullet which becomes a form of mechanical energy again. So we've seen energy not only transfer several times but convert twice.

This last one is where the point of contention comes in. The reason for this post was another post showing a pendulum being hit by a bullet, this is irrelevant. Unless your shooting squirrels with a centerfire the animal your shooting is stationary. The pendulum does have meaning in the way that it is also accepting the transferred energy from the bullet but since it's swinging it has also become the projectile. A good example of this is to shoot a chunk of 4x4 or 6x6 that is squared and most likely the block will blow off and the bullet may or may not penetrate completely. If you shoot a post buried in the ground with the same gun odds are it will go straight through.

The last part of this is basicly two parts, first is energy transfer, which in this case is mechanical to bilogical/chemical. If you shoot an animal with a .475 cal handgun using a 400gr hardcast and the impact velocity is 1200fps your energy will be roughly 1300ftlb's. If this bullet blows straight through and exits at 1100fps then you have only transferred a little over 100ftlb's of energy. If you shoot the same animal with a 400gr jacketed and it opens correcly and exits at 400fps you have tranferred a little over 800ftlb's of energy into the animal. So what do you gain from the jacketed that you didn't from the hardcast? More energy tranferred means a more massive shock wave going through the animal and this is why alot of times they drop in there tracks or stop after being hit. The second part of this pertains to the shock factor and wound channel. I've heard countless times that if a bullet is close to a half inch going in why do I need more coming out? The answer is you don't, but if a expanding bullet works correctly it will gain roughly 1/3rd in diameter so if 1/2" is good 3/4" is better. Now for the shock factor, when the bullet opens up in a body you need to remember that all living things are made mostly of water. When the bullet encounters these fluid and expands it rapidly slows not only cutting a larger wound channel but also creating a shock wave just like an earthquake makes a tsunami except more violent. I've seen many animals that have been hit in places other than the spine or vitals go straight down and when gutted the vitals and any other soft organ tissue in the area were jello.

Whether you put any weight into what I said is up to you but next time your in a swimming pull try this, first throw a jab under water with a closed fist, next do it with an open hand and last cup your hand. If you do this close to the surface or in a bath tub you'll not only feel the resistance but you'll see the difference in water displaced. The first would be equal to a hardcast, second an open jacketed bullet and third the cup of a hollow point.

This is not to say hardcast are not effective since they obviously can be but with everything there advantages and disadvantages. If you use the wrong jacketed bullet for animal type or velocity you may have a bullet failure or you may pencil hole it. The hardcast will penetrate deeper and can be usefull for heavy bones and awkward angles. The final decision is up to each shooter but all I'm trying to do here is provide information to allow for informed decisions. The jacketed bullets we have today are far superior to what we had even ten or twenty years ago this is why many African PH's have changed on buffalo from strictly using solids to using a soft point followed by solids or just soft points.