I don’t understand. Or maybe I do because most folks base the performance of defensive handguns on what they have heard and read over the years. After all, few of us have any real world experience with regard to how effective a particular handgun / ammunition combination is at stopping a bad guy when compared to another.
About the only way we have to compare options is to look at terminal performance. I compared the terminal performance of 10 popular, 9mm Luger and 10 similar, .45 Auto loads in 10 % ordnance gelatin. Here are the averages:
CARTRIDGE IV RD EF PEN
9mm 1222 0.60″ 1.68 14.55″
.45 Auto 989 0.66″ 1.46 14.97″
Difference 233 0.06″ 0.22 0.42″
IV = Impact Velocity, RD = Recovered Diameter, EF = Expansion Factor, PEN = Penetration
What does this mean? Due to the higher impact velocity and greater amount of expansion, the 9mm will on average produce a larger stretch cavity. The .45 Auto on average will penetrate about 1/2 inch deeper and bullets will have a recovered diameter of about 0.06 larger than a 9mm. (That’s a difference of less than the thickness of a quarter.)
But what about energy you say. Well, average 9mm kinetic energy at the average impact velocity was 381 ft.lbs. Average .45 Auto energy at the average impact velocity was 426 ft.lbs; a difference of about 10%. When you factor in recoil and magazine capacity, I just can’t really see a lot of difference. Modern bullets that have been optimized for the 9mm put it on a much more equal playing field with the .45 Auto.
Now, I’m sure COL Cooper, if he were still here, would give me a good lashing for this as many of you might as well. However, facts are facts. For a more detailed look at the terminal performance of these two cartridges as well as others, check out an upcoming article in American Rifleman. It will compare the actual terminal performance of 100 loads. Not sure when this article will run, but I’ll keep you posted.
Hey, I carry a Colt Commander in .45 Auto most often but if it were a 9, I wouldn’t lose any sleep over it.