Hello TFB, and welcome to a new column I’ve devised with the not-so-loyal and sometimes-helpful advice of the TFB Discord entitled “Love, Grampa Fudd” where with input from you readers, the TFB Staff, and members of the Discord, we’ll be tackling some of the most pernicious Fuddlore that still rears its ugly head. Without any further ado, let’s beat to death an argument that we’ve hashed out a million times.

A Letter from Grandpa Fudd

Dear Grandson,

I was at the range with my shooting buddies the other day, and my good friend Bubba’s nephew, Tactical Terry, said that 45ACP was outdated! Doesn’t he know that that puny little 9mm ain’t got no stopping power? We won two world wars with the stopping power of a 45!

Love,

Grandpa Fudd

Dear Grampa Fudd,

I’m afraid Tactical Terry is right. 45ACP is outdated, and there’s no such thing as stopping power. To explain this, we have to answer just one question. how do bullets kill? That’s actually a slightly more in-depth question than it appears at first glance. Bullets kill in one of two ways.

Firstly, through destroying the Central Nervous System or CNS. The CNS is concentrated in your brain and in your spine. A round that gets a CNS kill has hit either the brain or the spine and turned off CNS like flipping a light switch. This is the optimal outcome of any gunfight you are in because it represents the shortest amount of time between starting the shooting and ending it. So, stopping power. A 45ACP is bigger than a 9mm, so shouldn’t it be easier to get a CNS kill with 45 than with 9mm? Well, kind of, but also not really. As I’m sure you know, 45ACP bullets have a 0.451” diameter, whereas 9mm bullets have a 0.355” diameter. That’s a difference of less than one-tenth of an inch. That isn’t going to make any real difference when you compare that to the size of the human body.

But what about expansion? 45 is bigger than 9mm, so it should expand to a wider diameter, right? Again, true. A good defensive hollow-point pistol round will roughly double in expansion, making the 45 around 0.902” and 9mm 0.71”, but that’s only a difference of 0.2” (approximately). That is not going to help a CNS kill. So what about the energy of the round? High School Physics should have taught you that kinetic energy is 1/2 the mass times the velocity squared. So doing some paper napkin math (which I’ll spare you) the muzzle energy of 9mm ranges from 350 ft-lbs to 400 ft-lbs. The muzzle energy of 45ACP? Also about 350-400. So, nada.

The second way that bullets kill is through blood loss, also known as hypovolemic shock. This is the second best possible outcome to a gunfight. Blood loss can be fast, but it’s never as fast as a CNS kill, and someone who is bleeding to death can still kill you. Does 45ACP have an edge in this? After all, the bigger hole means faster bleed out, right? Eh. Not really. The difference between an arterial bleed coming out of a 0.355” hole and a 0.451” hole is nonexistent. Same with a 0.902” hole and a 0.71” hole.

What about temporary wound cavitation? We’ve all seen the gel tests in slow-mo where there’s this massive gap in the gel after a round rips through it. Isn’t that important? No. A temporary wound cavity is just that, temporary. I want you to imagine taking a piece of raw steak. Now pull on the edges really hard. Does it stretch? You bet. If you let go, does it look any different? Not really. Maybe if it had extremely low muscle content, which the human body does not.

Now, a permanent wound cavity is different. This is that little bit of give that remains in the steak after you pulled at it. The area that a bullet passes through, causing tissue damage, is the permanent wound cavity. But go ahead and watch as many gel tests as you can find, and they’ll all show the same thing. Permanent wound cavity of a 9mm or a 45 is so close as to be rendered meaningless by the size of the human body.

So Grandpa Fudd, to answer your question, stopping power doesn’t matter. Shot placement is the single most important factor. And there 9mm wins out over 45. Higher capacity and less recoil means that it’s easier to put more shots more accurately on target in a shorter period, making it more likely for you to hit something vital.

There’s nothing wrong with carrying 45ACP, but it offers no real advantage over 9mm. If you shoot 45ACP better because that’s what you’ve been shooting your whole life, go for it.

Your Loving Grandson,

Benjamin