Even a cursory scouring of gun forums, or listening to discussions at shooting ranges, will frequently uncover a discussion about “overpenetration” and the terrible dangers it represents.  Which is entirely understandable, as those of us interested in armed self defense are repeatedly lectured that “You are legally responsible for every projectile that leaves your weapon” and — if a bullet overpenetrates your attacker and strikes someone behind them, you are facing some substantial legal, financial, and emotional consequences.

Furthermore, fear of overpenetration is firmly ingrained by reading The Four Laws Of Gun Safety, where it’s stated: “Always be sure of your target, and what is behind it!”

With all that said, I’m going to raise a few eyebrows by just plain flat-out saying it: the paranoia about “overpenetration” is grossly overblown.  It’s not what you should be worrying about — or, well, it’s something you should be aware of, but it’s definitely not the most important thing and it’s not something to expend a tremendous amount of energy being concerned about.

Why Is Overpenetration (usually) Overblown?

There are a few reasons why I say this, but let me start with reason #1: you should be much more concerned with shots that miss the target entirely, than shots that penetrate through your attacker and keep going!  Missed shots are much, much more problematic than overpenetrating shots are.  There are lots of reasons for this, but I’m going to focus on two:

1.) You’re probably going to miss more than you hit.  Now, I’m not indicting you, or your marksmanship, or telling you you need more range time (although hey, we all need more range time).  I’m just acknowledging a simple, obvious fact — it’s really, really hard to hit a moving target when you’re terrified and fearing for your life and you’ve got more adrenaline coursing through your veins than you’ve ever experienced before and your body is overwhelming you with the “Fight Or Flight” instincts.  How hard is it?  Consider the statistics from the NYPD for officer-involved shootings — they’ve been keeping track of these stats for decades, and a brief study of them will reveal that for every six shots officers fired, they missed five of them.  Not “hit somewhere other than the desired point of aim”, not “hit in the shoulder” or “hit in the leg” or whatever, but — missed completely.  Five out of six shots fired by NYPD officers, on average, over the last several decades, missed the target completely.  Now, I know that some of you are thinking “well, that’s just because the NYPD has lousy training and officer certification, I KNOW I’m much better than they are!”  I’ve heard that argument advanced many times.  So I’d like to point out — the NYPD isn’t the only organization keeping statistics.  I’ve seen reports of more than a few, and in no case have I seen reports of the officers hitting more times than they missed.  Sure, the NYPD was the lowest ranked, but some other examples reported are Miami (between 15% and 30% from 1988-1994) and Portland at 43% (1984-1992); the highest I’ve seen is Baltimore reporting a 49% hit ratio.  Keep in mind, these are trained police officers.  Does that mean their training is superior to yours? Maybe, maybe not — how much do you train?  If you’re absolutely fervent about taking classes and training in true defensive scenarios, then maybe your training is on par or even better than the NYPD, but I’d dare say that that would be the case in only a minority, if not even a small or even tiny minority, of self-defense shooters.  For most of us, we go to the range once in a while, and we shoot paper targets.  That’s not training, that’s just rote marksmanship, and it has little (or nothing) to do with surviving a defensive encounter against a determined, fast-moving, armed attacker!

Secondly, I’d like to point out that police officers (yes, even those in the NYPD) are human beings who love their lives every bit as much as you love yours.  None of them wants to die.  I think it’s not likely that they’re blatantly ignoring training; whether the department offers top-line training or not, I think it’s likely that officers (who know very well that they’re far more likely to be shot at than the average citizen) even supplement their training.  And, given all this, they still only hit one time out of six.

What does that tell you?  It tells me that hitting a target, in that scenario, is really, really hard.  And you shouldn’t be surprised if you miss.  You should do your very best to hit, you should try your very hardest to hit, but — it ain’t easy.

Does this mean you shouldn’t even try?  Should you be so paralyzed by fear of missing, or fear of overpenetration, that you just put the gun away?  Again, let’s go back to why you’re carrying the gun in the first place… it’s likely (or should be) that you’re carrying it to protect you, or a loved one, from death or great bodily harm.  So if it’s a case of “don’t shoot and be killed” or “shoot and maybe you’ll have some consequences, maybe you won’t” then the old adage may apply here: “Better to be judged by 12, than carried by six.”

Now, on to reason two to not sweat overpenetration nearly as much as we seem to:

2.) Bullets get slowed down as they pass through someone.  A lot.  Let’s take the example of a .380 hollowpoint impacting an attacker at 1000 feet per second.  That bullet is capable of penetrating 13″ of ballistic gel.  Let’s say that it hits and passes completely through a thin attacker, and keeps going.  Assuming the bullet passed through, say, 9″ of soft tissue, how much of a threat will it still be? Using the formulas in Quantitative Ammunition Selection, we can find out — and doing the math, that bullet will still be traveling at 290 feet per second when it exits.  So yes, it’s capable of still doing some damage, certainly, but nowhere near as much as a missed shot would be!  Remember, the missed shot still has 100% of its velocity, so it’s still travelling at 1,000 feet per second, and it’ll hit something (a car, a wall, or maybe a bystander) and it will still be highly deadly.  The overpenetrating shot will still hit something too, but it’s at greatly reduced power.  It is much less likely to be deadly to a bystander than the missed shot would be.

Let’s take another example, the 230-grain .45 ACP JHP that travels at 850 feet per second — how much of an overpenetration threat would it be, after passing through 9″ of soft tissue of your attacker? Perhaps quite a bit less.  According to the QAS formula, that bullet would exit a 9″ torso traveling about 203 feet per second.  Now, that’s still capable of creating damage, but it’s certainly a much minimized threat as compared to a missed shot!

How much damage will these overpenetrating shots do to a person standing behind the target?  While there’s no way to predict exactly what will happen in any given scenario, we can look at probabilities and determine — they probably won’t do much damage.  How can I say this?  Thanks to ballistics experts and mathematicians who have modeled these parameters, we know that there’s a pretty good chance that these example overpenetrating bullets wouldn’t even break the skin of someone they pass-thru and hit.  Henry Hudgins of the US Army’s RDECOM Aeroballistics Division developed a formula for determining the velocity necessary for an expanded hollowpoint to break skin (with or without any chosen layer of clothing).  And according to Hudgin’s model, the .380 JHP I mentioned (exiting a 9″ torso and traveling at 290 feet per second) would probably sting when it hit someone else, but it’d be going slower than the 301.2 feet per second necessary to penetrate through 4 ounces of light clothing and then break skin.  And the .45 ACP example I gave, which exits a 9″ torso traveling 203 fps, wouldn’t even come close to the 295.6 feet per second necessary to punch through that 4oz clothing and then break skin.  So yes, that person may be bruised, but it’s probably unlikely that they’d sustain substantial or life-threatening injuries due to being hit by these example overpenetrating bullets.

Note, I’m not saying to ignore the concept of overpenetration.  I’ve embarked on an extensive quest to find the best .380 ammunition because I really don’t like the idea of using full-metal-jacket bullets that will easily penetrate 22″ of ballistic gel, because it seems like they’re guaranteed over-penetrators.  I certainly don’t want to accept the guarantee of overpenetration, when I don’t have to!  Hollowpoints are designed to expand so large that they minimize or largely eliminate the prospect of overpenetrating; most modern hollowpoints are designed to deliver about 12-13″ of penetration maximum.  But here’s the far bigger danger, to you: worrying so much about overpenetration, that you select ammo that actually under-penetrates.  That’s the real danger in this whole scenario.  Understand that an overpenetrating bullet will still stop an attacker; it just will also represent a threat to others (or property) by overpenetrating.  But an underpenetrating bullet is much more likely to fail to stop the attacker — and that means that the attack will continue.  Underpenetrating ammo was the whole reason for the debacle of the Miami FBI shootout, and the reason the wound ballistic conferences were called in the first place.  Underpenetration gets self-defense shooters killed.  Overpenetration may present some risk of collateral damage, but underpenetration presents the very real risk that you may not survive the encounter.

Overpenetration is bad, but underpenetration is much worse, and missing is far far worse.  Try to choose suitable ammo, and if you ever have to use it, try to be as accurate as possible, and you should be able to minimize your worries about overpenetration.

So what’s the general upshot?

Shoot only when you absolutely have to.  And be absolutely sure of your target, and do your very very best to hit them.  Be worried about missed shots, as those are far worse than overpenetrating shots.  And if a bullet overpenetrates, that’s disappointing, but the alternative (either not shooting, or using underpenetrating ammo) are both likely to get you killed.  A solid torso shot with a modern hollowpoint should minimize the risks of overpenetration.

Overpenetration can happen, but there are far worse things to be concerned about.  Don’t let fear of overpenetration unnecessarily cloud your judgement.  Choose reliable, effective ammo, and then train train train train with it, and pray you never have to use it.