3 Criteria for Effective Self-Defense Ammo

The importance of purchasing good self-defense ammunition for your everyday carry (EDC) handgun, or your home defense gun, is often overlooked. But what does it mean to say you should buy “good self-defense ammunition?”

Your ammunition should do three things consistently. Your self-defense ammunition should:

1. Reliably feed in your specific gun.
2. Consistently penetrate between 12″ – 18″ in ballistic gelatin
3. The projectiles must fully expand, consistently

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

Reliability:

If there is one thing that I'd consider being the most important, it's that the ammunition must cycle reliably in your gun, to begin with.

Expansion and penetration won't matter if your gun doesn't work with your chosen self-defense ammo. So, that is the most important one.

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 correctly.

Penetration:

Penetration is second because, even if the gun cycles properly, if the projectiles don't penetrate far enough into it, they may not do enough damage to stop the attacker. Therefore, you should choose self-defense ammunition that consistently penetrates between 12″ and 18″ when shot into ballistic gelatin. Keep in mind that ballistic gelatin is not the same consistency as human tissue. So 12-14″ on penetration in ballistic gelatin does not equal 12-18″ of penetration in a human body.

However, projectiles must penetrate deep enough to impact organs that cause the body to function normally. When this point is brought up, some will assume then that hollow point, self-defense ammunition, is designed to be “more lethal.” This isn't the case. Bullets are inherently lethal when they penetrate the body at hundreds of feet per second. Even so, not all projectiles are created equal, and some do not consistently penetrate deep enough to start incapacitation immediately. The point is to stop the threat as soon as possible and with the fewest rounds fired.

This is safer for the person defending themselves and the public, as each round fired could potentially miss the intended target and strike an innocent bystander.

We also do not want projectiles that over-penetrate. Bullets that pass through the intended target and strike unintended people are a problem. We will touch on this point again when we talk about expansion.

Many police agencies weigh penetration as an essential characteristic for their duty ammunition. This is because officers are more likely to shoot through barriers like auto glass and body panels than citizen defenders.

FMJ (full metal jacket, i.e., not hollow point) ammo tends to over-penetrate, which is one of the reasons why we always recommend using hollow points (JHP).

Expansion:

First, expansion is important because the projectile flattens as it impacts the threat. When the bullet expands inside an attacker's body, it causes a more significant wound tract and transfers more energy creating cavitation to the surrounding tissues. As a result, the round is likely to impact body functions more quickly and stop the attacker from continuing.

I mentioned this above in the penetration section.

When we talk about ending the threat, we are absolutely NOT talking about killing them.

The phrase “ending the threat” means EXACTLY what the simple definition of those words means. In other words, to stop the person from continuing to do whatever deadly threat action they were committing against the one using defensive force. This post explains a bit more about the difference.

Additionally,  expansion also helps limit the possibility that your bullet will pass through the bad guy and hit someone or something else (known as over penetration mentioned earlier).

Some manufacturers sell ammo that is supposed to expand but doesn't always actually do its job?

I recommend looking at penetration and expansion tests like what Lucky Gunner has done in their lab. They've shot many of the different types of popular ammunition into blocks of gel to see how far each bullet penetrates and expands.

The results may surprise you.

Some popular stalwarts have failed to expand or over and under penetrate in the testing constantly.

So how much expanding should a bullet do? Please don't get too concerned over the exact numbers; instead, choose a bullet that does it consistently. But for you who like numbers, a good rule of thumb is 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:

Put it all together, and you can find ammunition that will cycle reliably in your chosen self-defense gun. And a projectile whose penetration is constantly between 12-14″ when tested in ballistic gelatin.

Let's hear about the ammunition you choose to use in your EDC and why you carry that specific type. Leave a comment.

Also, if you're interested in solidifying foundation firearm shooting principles, check out this course called Shooting Fundamentals. It is a fantastic course for new shooters and those wanting to clean up some bad habits or consistency issues.