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I agree Dan, great post and excellent summary.

Bart wrote:If someone is buried in the ground and then shot, that makes sense. However, most criminals and victims who are shot are not buried or held immobile at the time. But in those special cases..........

My point is that if you're going to compare two different projectiles moving at different velocities, they will be roughly equal if the force is equal. The example of the baseball and the 400-lb boulder was not equal mathematically.

Bart wrote:

MojoTexas wrote:A better example, using the 30m/s velocity, would be a 2.27 lb rock (1.03 kg), which would be an equivalent amount of energy given the differences between velocity and mass.

Let's stick with the 400 lb boulder from his example. I would rather bump my head on a 400 lb boulder at a little over 2 m/s (5 mph) then get smashed in the head by a baseball at 80 m/s (nearly 180 mph)

I think you're imagining your head striking the boulder, not the other way around. Your head traveling at 5 mph does not have the same force as 400 lbs traveling at 5 mph. Imagine if you will if you were buried to your neck in a frictionless vacuum, and had a 400 lb boulder rolling at 5 mph at your head. If it struck your head at the same speed as a human's slow jog, I think it would do more than give you a little lump.

Here's another example with the same force: how about a 10 lb sledgehammer striking your head at 14.3 m/s (32 mph)? The 10 lb sledgehammer would have a mass of roughly 4.54 kg, and traveling at a velocity of 14.3 m/s would yield the same force in joules as the baseball at 180 mph. Both would probably be lethal.

I guess what I'm saying is that from a physics perspective, the faster you can push a round the better, since as the velocity increases the energy increases exponentially. There are other factors involved in "stopping power" however, such as bullet expansion, hydrostatic shock, etc.

MojoTexas

Vecco wrote:How about this would you rather get hit in the chest with an 80mps baseball or a 30mps 400lb bolder. The velocity of the smaller and lighter (less mass) baseball will not make up for the larger and heaver (more mass) 400lb bolder. Both can kill you, but one will have a better chance of stopping you then the other and is more lethal.

Not to nit-pick, because I understand what you're saying, but you'd have to balance the two equations for it to be a fair comparison.

The formula for kinetic energy is:



If you have a baseball (which averages about 145g) traveling at 80 m/s (meters-per-second), then the translational kinetic energy would be 464 joules.

If you have a 400 lb boulder (181.44 kg) travelling at 30m/s, the translational kinetic energy would be 81,646.62 joules.

A better example, using the 30m/s velocity, would be a 2.27 lb rock (1.03 kg), which would be an equivalent amount of energy given the differences between velocity and mass.

Yeah I know I'm a geek....

MojoTexas

baldeagle wrote:If you compare energy, expansion and penetration, the 9mm is at least the equal of the .45 acp from a scientific point of view in the size weapon that most people would carry. If you really want to start an argument, the .40 S&W is actually better than either the 9mm or the .45. It has about the same penetration as the 9mm (greater than the .45 acp), the same expansion as both the 9mm and the .45 acp, but higher energy than either of those loads. So theoretically, it should have the greatest stopping power of the three.

That means the 10mm Auto has all three (9mm, .40 S&W, and .45 ACP) beat, since it's just a .40 S&W cartridge that is longer with more powder (sort of like the relationship between .38 Special and .357 Magnum). One of these days I'll buy me a Wilson Combat 1911 chambered in 10mm...

MojoTexas

USA1 wrote:Why carry a .40 or.45

Because they don't make a .46

Technically they do make "bigger" calibers (depending on how you define "bigger"), but they're mostly impractical for concealed carry unless your a masochist. An example is the Smith & Wesson Model 329PD, which is a revolver chambered in .44 Magnum and only weighs 25.5 ounces. Most of the reviews I've read all agree that it kicks like a mule!

In my opinion, .45 ACP, or possibly 10mm Auto (which is just a "magnum" version of .40S&W) is about as "big" as I'd want to go for concealed carry. Also note that if you travel to neighboring Oklahoma (like I did a few weeks ago), it's "illegal" to carry anything bigger than .45 caliber, although I don't know how they define "bigger". The .44 Magnum is a much more powerful (and longer, length-wise) round than the .45 ACP, but it is smaller in diameter. IANAL, but according to §21-1290.6 of Oklahoma statutes:

Oklahoma §21-1290.6 wrote:Any concealed handgun when carried in a manner authorized by the provisions of the Oklahoma Self-Defense Act, Sections 1 through 25 of this act, when loaded with any ammunition which is either a restricted bullet as defined by Section 1289.19 of Title 21 of the Oklahoma Statutes or is larger than .45 caliber or is otherwise prohibited by law shall be deemed a prohibited weapon for purposes of the Oklahoma Self-Defense Act.

The subject of "best self-defense caliber" has been beat to death on this and many other public forums. Most experts agree that the #1 consideration is shot placement. A hit with a .380 is better than a miss with a .44 Magnum. If you can only have one handgun, you should carry the largest caliber with which you're comfortable shooting accurately. I have several handguns but when I'm carrying concealed, I mostly stick to either .38 Special (S&W J-Frame revolver--easy to conceal in summer) or my Kimber 1911 in .45 ACP.

Just my two cents worth, of course!

MojoTexas