Handgun over-penetration

Stop me if you’ve heard this one: “You shouldn’t use projectile XYZ because it will punch through the badguy and kill a bystander behind him.” It’s a common saw of gunshop logic, and yet you’d be hard pressed to find a verified report of it actually happening. Even in cases where projectiles exit the target human entirely, good luck finding an instance where a handgun bullet passed through a person and killed a bystander behind them outside of Indiana Jones. So is this all Hollywood myth, or is there a kernel of truth to old gunshop saying?

wound patterns after defeating a wall

Well, as it turns out there have been documented incidents in the late 80s and early 90s of people getting killed by bullets that had passed through another person. When reporting on these incidents, you have to bear in mind that the bullet technology of the time wasn’t nearly as advanced as it is today, and a JHP round of that era could be easily plugged by heavy clothing. This would result in it acting like an FMJ round, which means more penetration.

Yet even then, incidents of fatalities caused by over-penetrating bullets are extremely rare. It’s just not something that happens a lot, and there are two good reasons for that. The first reason is that shootings are statistically rare, despite what the anti-gun lobby would have you believe. People just aren’t getting lit up all the time, and when gunfire is exchanged it is frequently done in places without a lot of “other people” standing around gawking. There’s a low probability of getting into a shooting, and an even lower probability of getting into a shooting in a really crowded place. The math just isn’t in favor of overpenetration injuries.

The second reason is also important – the human body is an amazingly resilient structure. Combine that with the relative lack of power that handgun bullets deliver to their target, and “shoot-throughs” that have enough energy left to hurt another person become even more rare. Perhaps if you’re talking about rounds through extremities that don’t contact bone, sure. But good hits in the upper thoracic area? Those would have to penetrate the sternum, a bunch of internal organs, and then come out back through the ribs or spinal column, all while maintaining enough energy to wound another person. That’s…highly unlikely.

The Gun Nuts Bottom Line: While there is some concern of overpenetration with a handgun cartridge, your primary concern should be that your defensive round of choice will have sufficient penetration to reach vital organs and cause incapacitating blood loss in an attacker.


  1. Is the image sourced from a study of some sort? Do you have a link to the source?

    1. I don’t know, I’ve had this image on my hard drive basically forever and finally found a semi-legit use for it.

  2. I’m no ballistician, but think about how underpowered a handgun is… Then imagine how underpowered that same bullet would be after it has already penetrated 12″ of tissue an maybe slowed down to 100fps…

  3. Jason — In other words, “All handguns suck. Some suck more than others, but ALL suck.” Which is something everyone who carries a handgun should keep in teh front of their mind.

  4. It is worth noting that the article addresses bullets that BOTH (a) hit the intended target somewhere AND (b) KILL (not just wound) the bystander. When you break this down, it is a very unlikely event.

    In a defensive shooting situation, bullets that miss the intended target and kill a bystander aren’t counted here.

    Even when you hit what you’re aiming at initially, not all GSW’s are fatal. So even if your bullet passes through the intended target, it still would need enough velocity and mass AND (most importantly) aim to kill. The odds of fatal damage are slim, but the odds of ANY damage are not necessarily negligible.

    ALL THAT SAID, the important point to remember is that from the moment you buy a bullet (and store it, load it, shoot it, etc.) until the last fragment of it stops, you own it, and while the odds that it will KILL unintentionally when properly aimed are very small, you still could–as the movie says–“shoot an eye out.”

  5. Would you take a shot at a BG knowing someone you didn’t want hit was behind them? Barring that predicament it’s all speculation as in life there are so many possible outcomes. It’s like picking ammo with low over penetration for Police use when at most only 30 percent of their shots hit the intended target.

    We should be careful not to gag on gnats while swallowing elephants.

  6. Stop with the gun shop logic put down. Theres plenty of dumb asses who own guns and wax poetic about matters they know nothing about whether at the the shop, at the range or behind a badge, plenty of people who dont know squat act like they do. Lets not act like its religated the the people behind the gun counter. When i was hired at a fire arms dealer I immediatley downloaded a pdf of my states firearms laws to be more familar with the intracicies that i was at that time unfamilar with. I routinely follow many online resources for product releases and knowledge about emerging tech and techniques. Its the lazy bastard found everywhere that just parrots what he has been told as gospel truth.

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