I finally read this article by Jason Hanson. I regard him as a twit based on previous articles, but since there seemed to be validity from a lot of the posters here, I tried to read his article with an open mind. He gives no citations for the information he purports, then at the end of the article claims that his Speer Gold Dot 124 gr 9mm has similar ballistics to the .40.
Speer 124 gr 9 mm:
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Speer 180 gr .40:
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The 9mm has 364 ftlbs, the .40 420 ft lbs of energy. This gives the .40 a little more than 15% more energy. But where does that energy come from? Let's look at the mass of the bullets. 180 gr versus 124 gr. The .40 is over 45% more massive. This means that to get the 9mm near the same energy it has to do it by increasing the speed of the bullet. A faster lighter bullet always penetrates more and expands less. A heavier slower bullet with similar energy expands more before it stops since it is harder to stop something with more inertia.
So in comparison with the rounds Jason says are similar. The .40 in the brand he quotes has more energy and is a more massive bullet (more mass more inertia, more expansion). The speed is the only thing the 9mm has over the .40.
If I had to pick between ONLY these two rounds, the data tells me to go with the .40.
The .45 speer gold dot 230 gr has this:
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Note: 404 ft lbs of energy (more than the 9mm, less than the .40) and only 890 fps (considerably slower than the other two rounds). Again, a much more massive bullet that is slower AND has more energy. It will do more damage than a 9mm as well.
For those that don't know the equation for the energy of a bullet it is equal to 1/2*mass*speed squared. Since speed is squared, a slight increase in it yields more energy. But more energy in a lighter round usually means more penetration and less expansion.
Is 9mm suitable, yes. Is it better than the .40 or .45, in my opinion no. I'll take bigger and slower going into you than faster and lighter as a self-defense round any day. There is a reason why the .40 was developed by the FBI when their 9mm weapons were ineffective during their shootout in Miami.
Also, this is a direct quote from his article:
"
In fact, the only reason that the police switched from 9mm to .40 in the first place was because of the Assault Weapons ban of 1994. The 1994 law banned the production of high capacity magazines, however, you could still sell “pre-ban” magazines. So the gun manufacturers went to police departments and offered big incentives to upgrade to the .40 so they could get the departments to turn in the high capacity 9mm magazines that they could resell for a huge profit."
This is absolutely false. Read the history of the .40. It was developed by the FBI to be a round comparable in energy to the 10 mm but in a round that was sized like the 9mm. Since it was proven to be more effective, police departments, using the FBI data started switching over. Again, the glock 22 (.40 cal) is 15 rounds, the glock 17 (9 mm) is 17 rounds. Hmmm, yeah, high capacity ban my big toe!
Here's a good article that goes into the history and effectiveness of the .40.
http://dailyoddsandends.wordpress.com/2012/08/27/does-the-40-sw-get-enough-credit/