It’s said that racing began with the production of the second car. Long before that, though, and in a much more serious way, people have debated the best firearm cartridge from the moment there were more than one.

Modern semi-automatic handguns come in fairly standardized calibers these days, ranging in size from the .22 LR through .25, .32, .380 (aka 9x17mm), 9mm (aka 9x19mm), .40, 10mm, and .45, . That’s a lot of choices, which means a lot of arguments! That’s excluding some less common variants, and all the revolver calibers.

Of these, the ones commonly cited as “duty” arms are typically cited as 9mm, .40, and .45. By “duty” one means, or ought to mean, firearms intended for use by law enforcement officers and other public defenders whose job may entail stopping and apprehending persons who are committing or have committed crimes. To this end the FBI has developed a protocol to, as best as presently possible, objectively evaluate a combination of a firearm and cartridge to stop an offender.

The FBI protocol

The FBI uses a uniform substance emulating flesh — 10% ballistic gel. While recognizing that people have bones, sinew, muscle, fat, nerves, and organs, this substance provides uniformity in testing. So: misses are useless, and hits that fail to be directed at a vital area may fail to stop an offender, but that’s the role of training, and less so the role of the arm itself. The FBI test is intended to provide an officer with an effective weapon with which to employ their training. This test involves:

  • Bare gelatin
  • Heavy clothing on gelatin
  • Light clothing behind a steel barrier
  • Light clothing behind a wallboard barrier
  • Light clothing behind a plywood barrier
  • Light clothing behind an automobile glass barrier

Lastly, this protocol is looking for 12″-18″ of penetration, and expansion of 1.5x the original size, in order for the round to have the best chance of effecting that stop (gel is not flesh, it’s a test).


This is about where we come in. The general public does not have a “duty” need. The officer has a duty to protect the public, and having engaged the offender, needs to stop them and, ideally, apprehend them, even when they’re taking cover or concealment behind steel, drywall, or other barriers. You or I on the street have a different need. Our need is to make the threat stop. If the threat runs away, great. If it takes cover, we can leave; again, great. In fact, some of the barriers above are things we would very much prefer not to shoot through, especially if we’re in a home, business, or office where family, co-workers, or bystanders might be.

Our ideal round is not necessarily the same as the officer’s — but there are many similarities. If we’re forced to shoot in self-defense (presuming our threat doesn’t quit, run away, or hide) we very much need our action to stop the threat — maybe more so, as we may not have an armed partner and government behind us. Accordingly, on ammunition sites and YouTube vloggers alike the barrier tests are usually not replicated, and you’ll find tests largely involving bare gel or denim/cloth/fleece “heavy clothing” (and the occasional bag of oranges). This set of articles uses the 12″-18″ FBI standard, not because the .380 ACP is a duty round, but because some objective standard is better than none. When making your own choice, keep in mind this is about personal defense, not duty.

That said, in the general case there are many calibers, and since the public is more likely to carry concealed, handguns other than full-sized duty arms come into play. This introduction is long enough, so I’ll get right to the meat of it by noting that a) hardly anyone makes truly “pocket” pistols in 9mm, .40, or .45; and between that and the rounds’ power, b) if those calibers are your choice, you need only avoid the extremes to find a viable round. This article isn’t about traditional “duty” calibers.

This series of articles is about the .380 ACP, which depending on your existing choices, friends, or experience might be thought of as the goldilocks round for self-defense, a good backup, or a complete waste of time.


When I first compiled my information and made a side remark to my initial findings, one Internet forum poster asked what conditions I used for my test. A very insightful remark! Depending on where you look, at this YouTuber or that site, you might conclude that Hornady XYZ or Speer ABC is complete junk or awesome. Not surprisingly, perhaps, you may notice that people test with different arms, in different weather, with the equipment they have; their “heavy clothing” may differ, and environment may play a role. Ideally, it’d be nice to assume that Winchester MNO is what it is and if a site gets certain results, you will too. A quick look at two or three sites will quickly cause you to lose that opinion! Clearly, shooting one, two, or five rounds into gel does not entitle us to make a definitive conclusion!

So: a brief word about data science. It isn’t magic, it isn’t “AI,” and it can’t predict everything. All it is, really, is the same averages and other math you might have used in a basic statistics class (or in Excel) but lots and lots of it. Adding lots of data turns “anecdote” into “information” as long as we keep the limitations in mind: we can’t “prove” anything this way but only infer and rule out the “null hypothesis” or contrary position. If I show that the moon is not made of cheese, you can’t say I’ve proved it’s made of wine. (Silly example but you get the point, I hope).

Accordingly, this study doesn’t “trust” or “distrust” Shooting the Bull 410, Lucky Gunner, or any other author. It pulls together 330+ rounds from 12 different authors, 12 different firearms, and 29 different types of ammunition, all in .380 ACP.

In the next installation I’ll describe all this data and share some pretty pictures (or as we say in the data science biz, visualizations); from there we’ll see if we can draw some estimates when authors publish partial data (say, they have the round, a given firearm, and a chronometer, but not ballistics gel). Finally, we’ll see if all this adds up to a way to decide, whether armed with a tiny Beretta Pico or a long-barreled S&W EZ380, which ammo choices are likely to result in the FBI-spec 12″-18″ penetration and 1.5x expansion — maybe just “a” standard, but currently the best benchmark we’ve got.

By Wererat

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