Not taking away from Caleb’s argument that we spend too much time arguing about stopping power. We do. Shot placement matters a whole lot more. But that aside, I do want to look at one thing Caleb mentions.
When you look at a 9mm, a .40, and a .45 ACP all right next to one another like that, the size difference is almost laughable
You have to look at it from a mathematical point of view, because your instincts when it comes to area and volume are deceptive. For the same reason, a 21″ monitor doesn’t look that much bigger than a 19″, but it is. Area for a circle is A=Ï€r2. In that case, let’s take a look at 9mm vs. .40S&W vs. .45ACP. After all, it’s the area of the bullet that slices through the target, not the diameter.
|Round||True Radius (D/2)||Surface Area (A=Ï€r2)|
So you can see when it comes to diameter, the difference is minimal, but that doesn’t translate when you think about it in terms of surface area cutting through the target. In this view, .40S&W is 27% larger than 9mm, while .45ACP is 62% larger than 9mm and 28% larger than .40S&W. That’s not even considering expanding ammo, which is going to make the numbers even more dramatic.
That also holds when it comes to how much mass you can throw down range, and since stopping power is arguably derived from momentum, sending a 230gr bullet of a .45ACP downrange is going to matter a lot more than the 200gr .40S&W bullet or the 115gr 9mm. Never make the mistake of just thinking about bullets in terms of diameter (caliber). When you start thinking about area and mass, the numbers change more dramatically than instinct would have you believe.