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The Three Necessities For Self-Defense Ammo

How Many Bullets Should You CarryHere we go on ammo again. This time, however, I'm not really going to talk about the shortage. I feel like it's time to shoot that horse so it stops suffering from its wounds. But it is important to pick out the right ammo, especially during a massive shortage like we're currently seeing.

Otherwise, you'll just be wasting your money on ammunition that may not be effective at stopping a bad guy as well.

Another way of putting it is that just because you bought a box of “hollow points” doesn't necessarily mean you bought something that is going to consistently work for you if you have to pull the trigger in self-defense.

What I mean, is that you need your ammunition to do three things consistently in order for you to feel confident that it will stop an attack from continuing. Here are those three things in what I'd consider to be the order of importance:

  1. Reliability
  2. Penetration
  3. Expansion

Let's take a look at each one more in depth below.


If there is one thing that I'd consider to be the most important, it's that your gun needs to be able to fire the shot off to begin with.

Expansion and penetration won't matter if your gun doesn't work with your chosen self-defense ammo. So, that really is the most important one. But it goes a step further than being able to actually shoot the gun.

You also need to reliably and consistently hit your target with your chosen ammunition. If you can't, then you need to figure something out.

We always recommend that you run a few boxes of your chosen self-defense ammunition through your gun to make sure they cycle properly. Never assume that it will, and in the case of using +P ammo (meaning that it's higher pressure), the harder-recoiling ammo may throw your follow up shots off, so knowing if you can shoot it is important.


Penetration is second because, even if the shots cycle properly if they just bounce off your attacker, or at least don't penetrate far enough into it, they may not do enough damage to stop the bad guy.

Many police agencies also place penetration over expansion for much the same reason. At the end of the day, the bullet needs to make it at least so many inches into the human body to be worthy.

We all use the FBI standard which means that in order for a bullet to be considered effective it needs to penetrate somewhere between 12 and 18 inches.

If it doesn't hit the 12 inch mark, it's considered to be underpowered. If it goes outside of the 18″ point, the bullet can leave the body and hit another person. Obviously either of those scenarios is a bad recipe.

FMJ (full metal jacket, i.e. not hollow point) ammo has a tendency of going the over penetration route, which is one of the reasons why we always recommend using hollow points (JHP). When the bullet expands it actually helps to slow it down faster, leaving less of a chance for the round to leave that body and go into another, innocent one.


Expansion is important because as the bullet expands inside an attacker's body it does more damage inside that body (because the projectile grew in size and essentially makes a bigger hole). When more damage is done there is a higher chance that your bad guy will stop attacking you sooner.

In addition to the bigger hole, it also helps to ensure that your bullet won't exit the bad guy and hit someone or something else (known as overpenetration).

What if I told you that some manufacturers sell ammo that is supposed to expand but doesn't always actually do its job?

What I recommend is looking at penetration and expansion tests like what Lucky Gunner has done in their lab shooting rounds into gel. They've shot a lot of the different types of popular ammunition into blocks of gel to see how far each bullet penetrates and expands and you may be surprised by the results.

Some of the popular stalwarts have been shown to be ineffective in their main job, while other, lesser known rounds do fantastic.

Of course the gelatin isn't a completely accurate representation of the human body but it gives a pretty accurate description of how well each round will perform when it hits a human body.

So how much expanding should a bullet do? Well, a good rule of thumb is that a bullet expands to be 1.5X its original diameter. But as far as I know, there is no standard. I've also read 1.7X, and a few other arbitrary numbers.

For me, in a typical 35 caliber bullet, like 9mm, I like to see the bullet get to at least .5″ in diameter, preferably bigger.

Put it all together:

When you put it all together you find ammunition that will cycle reliably in your chosen self-defense gun that also reaches the optimal penetration set forth by the FBI Standard, that also expands enough to do the necessary internal damage to stop a bad guy.


That Lucky Gunner lab test, while great, is a few years old and there have been plenty of new releases of ammo not found on that list, like Federal's Punch and Deep. I'm really interested to see how they perform. I have some Punch and may try to conduct some tests myself, but only time can tell.

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6 Responses to The Three Necessities For Self-Defense Ammo

  1. Mark Linebarger January 4, 2021 at 5:26 am #

    Anytime you make an ammo change, you need to verify they will run thru your firearm. Eg; some semi autos don’t like a lot of exposed lead on a jhp…and some of the new defense stuff with the splits/laps in the jacket are creating feed problems in some firearms
    All this speaks to your first criteria.

  2. V January 4, 2021 at 12:03 pm #

    I did carry hollow points but had 2 where the nose went back into the round, ie, the round was shortened so it dropped down so it wasn’t in the chamber. 2 rounds had to be extracted manually. I’ve since switched back to practice rounds to carry–not my preferred choice. At home, I practice with standard rounds, and as for now, still use them when cc. Not my preferred choice. With the lack of ammo available, people can’t practice to be proficient, so what are we supposed to do. Responsible firearm owners want to be able to defend ourselves and innocents and NOT risk bystanders…

  3. Mitch January 4, 2021 at 1:00 pm #

    Shoot that horse? Really.
    What of its family?

  4. Mitch January 4, 2021 at 1:23 pm #

    Though I appreciate the “wound” part, i am neither a horse or alone in this.

  5. Zach January 4, 2021 at 9:28 pm #

    What is “…typical 35 caliber bullet…”??

  6. David Tyree January 5, 2021 at 9:47 am #

    I only wish I could get the ammo I want. Right now you have to gram whatever you can get. In the old days, yes, I would use one allowable brand of ammo. Not available now.

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