Long Answer to a Gun Question

Brad Warthen asked a question in a comment on a blog post regarding guns yesterday. His comment/question was:

I’m probably going to show my ignorance here, but doesn’t a 9mm or a .38 caliber slug have a lot more stopping power than a .223?

Admittedly, I can barely hit a wall with a handgun, but I’m sort of thinking this is less about marksmanship and more about bringing a weapon to bear quickly in the general direction of an intruder. How many burglars are going to stick around to see how good a shot you are when the room is filled with the roar of a handgun, and a muzzle flash has stabbed out in their general direction?

Which sort of takes us back to a previous discussion about dogs, another excellent answer to the question, “What is most likely to make a burglar leave your house immediately and never want to come back?”

Now, if we’re talking about something else here, if the issue is whether one can most reliably kill an intruder, rather than run him off (or get him down on the floor with his hands behind his head), then we’re getting into a different sort of discussion, with very different ethical implications.

I didn't have time to write this essay at the time, and I know he probably doesn't want my long-winded answer over on his blog anyway, so I'm posting it here. If you're not a gun person, please skip this and wait for additional content. If you like guns and ballistics, you probably already know most of this.

First, let’s deal with first principles. When you are in a home defense situation, your goal as the homeowner is to stop the intruder from attacking you. If he wasn’t attacking you or causing you to reasonably fear for your life and/or personal safety, then you shouldn’t be shooting at him. You should probably be yelling at him. Someone rooting around in your outside rose garden shouldn’t be shot. Someone running down your hallway towards your bedroom with a knife probably should be shot. (Hey, the first rule of a gun fight is to bring a gun. Sorry, bro.)

For purposes of this, we’ll assume that you’ve decided to fire your firearm to stop the assailant. Notice I said “stop”, not kill. You want the bad guy to stop doing whatever it is they are doing that caused you be afraid for your life. Whether they live or die is really irrelevant, and that’s their problem, not yours.

You could try to get the assailant to stop with psychology- they see you with a gun (or they hear you rack the slide on your pump shotgun) and they say “Oh no, Brad has a gun. I’m outta here”. That’s one way to do it.

Unfortunately, you cannot control how the bad guy analyzes things, and maybe their thought process isn’t as rational as yours or mine. Maybe you’ll get a lazy criminal who doesn’t want to challenge someone with a gun, or maybe you get an evil person who just isn’t going to stop. That person will have to be shot...probably more than once.

So, you need to stop a person physically. The question then becomes what is the best tool to do that? Brad has offered the choice between “9mm” a “.38 caliber slug” and “.223”. Let’s talk a little bit about ammunition basics so we can properly define what we’re talking about.

Let’s start with “.38 caliber slug”, since that’s the oldest cartridge. I assume that you are referring to the .38 special, which was the standard issue service cartridge for almost all police departments in the US from about the 1920’s until the 1990’s. Interesting note, the bullet’s diameter, isn’t actually .38 of an inch in diameter; it’s .357 of an inch. Sound familiar? Right, it’s exactly the same bullet used in the much more fearsome .357 magnum. Except for case length (which allows for more powder, which equals more speed), the .38 Special is identical to that of the .38 Long Colt, which the .38 special replaced. Why did it replace something exactly the same size?  Well, it didn’t have effective “stopping power”. In the Phillipine-American War, it didn’t stop charging enemy combatants at close range:

Antonio Caspi, a priosoner on the island of Samar, P.I. attempted escape on October 26, 1905. He was shot four times at close range in an an encounter by a .38 Colt's revolver loaded with US Army regulation ammo. He was finally stopped by a blow on the forehead from the butt end of a Springfield carbine.

Obviously, you don’t want to have to shoot someone four times at close range AND THEN have to smack them on the head. I mean, who has the time for that? So the .38 special was designed in 1898 to increase power. It came out faster than it’s parent case, therefore, more power. Unfortunately, by today’s standards, it’s about one of the slowest rounds out there.

A standard .38 special pushes 158 grains (about 10 grams) of bullet out of the barrel at a speed of 940 feet/sec. By comparison, the 9mm pushes 115 grains (about 7.5 grams) of bullet out of the barrel at 1,300 ft/sec. And the .357 magnum, the exact same bullet as the .38 special comes out at 1,349 ft/sec. However, we’re ultimately talking about energy here though. You want to put the most energy into your attacker. Force = Mass x Velocity Acceleration. [It has been brought to my attention that I am wrong on this. Hey, I'm a lawyer, not a physicist.]

.38 special: 420 Joules

9mm: 570 Joules

.357 magnum: 866 Joules

Note, these are all full metal jacketed rounds, not hollow points that expand upon impact. We’re not even getting into different bullet shapes yet.

As you can see, a lighter, faster bullet can give you more energy or “stopping power” than a heavier, slower one. Accordingly, most police departments switched to the 9mm or some other cartridge as their primary service issue. Basically, .38 special is an obsolete round now. Accordingly, I would not recommend it for anything other than practicing with in your .357 magnum handgun.

So that’s an important principle: the speed of the bullet is just as important as it’s weight.

Ok, into the future. We’re moving forward from the obsolete .38 special designed way back in 1898 to the modern 9mm designed in 1902. Wait, what?

“9mm” Far and away, when someone says 9mm, they mean 9x19mm Parabellum or (9mm Luger). This cartridge was designed way back in 1902 for the German luger. It’s a great cartridge with a long history. Interesting note, “Parabellum” may sound familar to Brad and other good Catholics who took latin in Catholic school Si vis pacem, para bellum ("If you seek peace, prepare for war"). para bellum, get it? Pretty cool if you ask me. They sure knew how to name stuff back in 1902. Anyway, I digress.

As illustrated above, the 9mm cartridge pushes a lighter bullet pretty quickly. It’s also compact enough of a cartridge that you can have more cartridges in your magazine. Sounds pretty good, right? That’s why it’s one of the most popular pistol cartridge in the world. It’s easy to see why it replaced the .38 special. You can have the same sized handgun shoot 20 9mm rounds or 6 .38 special rounds. It’s a no-brainer. Now, with modern ammunition and using a hollow point that allows the bullet to expand (rather than pass entirely through the person) you can get a very solid 630 J of force out of a 115 grain 9mm. Personally, it’s what I use in my carry gun. To be fair to everyone who’s going to e-mail me about the .45 ACP, the Browning round delivers a higher dose of energy. I know, I know...I digress.

Ok, those were two handgun cartridges. How do they compare to the .223, which is a rifle cartridge?

The .223 is a very modern cartridge, comparatively. It was designed in 1964, which is like last week in gun time. Let’s look at the ballistics of this rifle cartridge:

It sends a very light bullet out. Let’s go with the standard 55 grains (although there are plenty of other weights available for the .223 chambering). The .223 sends that light round out at a blistering 3,240 ft/sec. Remember the big ol’ .357 magnum? If you’ve ever fired one you know it’s a dragon. That thing only has a muzzle velocity of 1,349 ft/sec. (But remember, it's sending a heavy bullet.)

For the .223, that translates into a massive 1,738 J at the muzzle. That’s more than double the energy of the .357 magnum, and the .223 is a whole heck of a lot easier to get proficient with. Not bad, eh? The energy is what drives a deep wound into the target, causes massive trauma to the surrounding tissue, and stops someone.

That’s the difference between a rifle and a handgun right there. Speed. There’s a reason the United States Military uses this as the standard round for it’s main battle rifle. It’s a deadly round out to about 200 yards, which is where most combat takes place. You will kill a person. It’s not a “varmint” cartridge, no matter what people tell you. Past 200 yards, the light bullet starts to lose it's speed (and therefore it's energy) very rapidly. It becomes less effective.

However, anything human sized in a range less than 200 yards, the .223 is deadly. If you want to take moose or elk or big game at longer ranges, the .222 is not the right tool in the toolbox. But a heavy grain bullet is perfectly fine white-tail deer hunting. You could fill the freezer with deer meat. But we're not talking about hunting, we're talking about home defense. By the way, you can't hunt deer with a 9mm pistol unless you're really sneaky. I know...I digress.

Anyway, back to the home defense question. I think we can rule the .38 special out. It’s not what you want anymore. It's slow and it has low capacity. Not a good combination.

That leaves the 9mm and the .223. The ballistics of these rounds are both very good, so the big difference is: Do you want to shoot a handgun or a rifle? The shot will be a close one. We're talking 10 yards or so, probably less. That's what it really boils down to, and that’s a personal preference. The most important thing is to use what you are comfortable with and can actually hit something with. If you can’t hit the wall with a 9mm handgun, it’s not going to be very effective beyond being a big scary noisemaker. If you feel like the rifle is too cumbersome, then maybe you’re a handgun guy. There’s no wrong answer here, really. There’s only the right answer for you.

Me personally, I can dust clays with my shotgun all day, and quail tremble at my approach, so I’m going to stay with my shotgun loaded with buckshot for home defense. I can run a shotgun better than any other gun I own because I use it more. Use what you know how to use. If the answer to that is “dogs” maybe you shouldn’t own a gun. If you made it all the way to the end of this post, you're a champ.