Handgun caliber and lethality.

This post is NOT about gun control, even though the article which it references specifically is. I don’t want to get into that discussion here, and will delete any comments which attempt to discuss it.

Rather, I want to look at the article in order to better understand ‘real world’ handgun effectiveness, in terms of the article’s conclusions. Specifically, as relates to the correlation between handgun power (what they call ‘caliber’) and lethality.

First, I want to note that the article assumes that there is a direct relationship between caliber and power, but the terminology used to distinguish between small, medium, and large caliber firearms is imprecise and potentially misleading. Here are the classifications from the beginning of the article:

These 367 cases were divided into 3 groups by caliber: small (.22, .25, and .32), medium (.38, .380, and 9 mm), or large (.357 magnum, .40, .44 magnum, .45, 10 mm, and 7.62 × 39 mm).

And then again later:

In all analyses, caliber was coded as either small (.22, .25, and .32), medium (.38, .380, and 9 mm), or large (.357 magnum, .40, .44 magnum, .45, 10 mm, and 7.62 × 39 mm).

OK, obviously, what they actually mean are cartridges, not calibers. That’s because while there is a real difference in average power between .38 Special, .380 ACP, 9mm, and .357 Magnum cartridges, all four are nominally the same caliber (.355 – .357). The case dimensions, and the amount/type of gunpowder in it, makes a very big difference in the amount of power (muzzle energy) generated.

So suppose that what they actually mean is that the amount of power generated by a given cartridge correlates to the lethality of the handgun in practical use. Because otherwise, you’d have to include the .357 Magnum data with the “medium” calibers. Does that make sense?

Well, intuitively, it does. I think most experienced firearms users would agree that in general, a more powerful gun is more effective for self defense (or for offense, which this study is about). Other things being equal (ability to shoot either cartridge well and accurately, concealability, etc), most of us would rather have a .38 Sp/9mm over a .22. But when you start looking at the range of what they call “medium” and “large” calibers, things aren’t nearly so clear. To borrow from a previous post, this graph shows that the muzzle energies between 9mm+P, .40 S&W, and .45 ACP are almost identical in our testing:

 

Note that 10mm (and .357 Sig) are another step up in power, and that .357 Mag out of a longer barrel outperforms all of them. This graph doesn’t show it, but .38 Sp is very similar to 9mm, .45 Super is as good as or better than .357 Mag, and .44 Magnum beats everything.

So, what to make of all this? This claim:

Relative to shootings involving small-caliber firearms (reference category), the odds of death if the gun was large caliber were 4.5 times higher (OR, 4.54; 95% CI, 2.37-8.70; P < .001) and, if medium caliber, 2.3 times higher (OR, 2.25; 95% CI, 1.37-3.70; P = .001).

certainly seems to carry a lot of import, but I’m just not sure how much to trust it. My statistical skills are not up to critiquing their analysis or offering my own assessment using their data in any rigorous way. Perhaps someone else can do so.

I suspect that what we actually see here is that there is a continuum over a range of different handgun powers and lethality which includes a number of different factors, but which the study tried to simplify using artificial distinctions for their own purposes.

Which basically takes us back to what gun owners have known and argued about for decades: there are just too many factors to say that a given cartridge/caliber is better than another in some ideal sense, and that each person has to find the right balance which makes sense for themselves in a given context. For some situations, you want a bigger bullet. For other situations, you want a smaller gun. And for most situations, you want what you prefer.

 

Jim Downey