Is the .40 really more powerful than 9mm?

O

Oysterboy

New member
As I was browsing around on calibers I came across the chamber pressure chart. It showed that the .40 and the 9mm (both standard) showed 35K psi. I know that the .40 bullet, say 165, is heavier compared to 9mm bullet, say 147, but as I learned the heavier the bullet the lower the velocity thus less energy.

Yet I've seen charts that showed the .40 expends more energy than the 9mm. I'm missing something here, what is it?

Thanks
 
I had the same experience in a smg shootoff. I used a MP-5 in 40 and my opponents were using MP-5 in 9mms. A two shot burst from my gun easily knocked down the plates. The 9mm hits wavered a bit. I knocked down my plates faster than anyone else thanks to the bigger bullet.
 
A google search for handgun ballistic tables, or handgun ballistic calculator will give you much data.
As a simple example, Remington shows the 125 GR. 9MM Golden saber has 339 ft lbs of muzzle energy, while the 165 GR. 40S&W produces 485 ft lbs of energy.

but as I learned the heavier the bullet the lower the velocity thus less energy.
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In the same cartridge! The 40S&W cartridge is larger, and has a larger volume for more powder capacity, thus higher velocity.
 
+1 Cheapshooter!

I'm personally not a fan of the .40SW the cartridge is definitely more powerful than its 9mm counterpart.

In fact I think I remember reading it carried more energy downrange than even the .45acp!

Regardless of that I'll stick with the .45acp. IF I need more impact power than the .45acp I'll go for my .44mag or better yet grab a carbine!
 
Here's another one to think about: the .357 magnum also operates at similar pressure levels.

Chamber pressure doesn't really tell you much. A brass casing can only take so much pressure. Also, you don't really know anything about the duration of the pressure.
 
Yes it is

The .40 S&W pushes a 155 grain bullet notably faster than the 9mm pushes a 147 grain bullet.

I distilled some information from Ballistics By The Inch comparing several handgun rounds. They didn't use the same make & model loads from one cartridge to another. I selected what looked to be the strongest loading from their list for each cartridge. In these graphs you can see that the 115 gr 9mm is faster than the 150 gr .40, but momentum and energy are clearly in favor of the .40. Since the .40 S&W and 357 Sig have essentially the same powder capacity, I suppose that loading a 125 grain bullet and the same powder mass into the .40 would produce similar energy to the Sig.

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Seems Kozak6 is about right in that chamber pressure is not relevant here.

The 40S&W is a more powerful round in general. A heavier bullet can be fired from the 40 than the nine. That same bullet can be fired at the same or a higher velocity.

tipoc
 
The .40 s&w can fire a larger, heavier bullet at the same velocity as a smaller 9mm bullet, so yes technically the 40 s&w is a more "powerful" caliber. This can help with barrier penetration and the 40 s&w tends to deflect less than the 9mm when hitting a barrier or obstacle because of the heavier bullet. That said, any full power service caliber (9mm, .357, .40, .45) are more than capable. Since I'm not an LEO, I've always found the added recoil of the .40 s&w negated any benefits of the load vs. the 9mm.
 
Yes.

All other things being equal, the larger the diameter of the bullet and the faster it goes, the more "powerful" it is.

The problem is "effectiveness".

Is the shooter able to "effectively" use that greater power?

Personally, I can't.

Just yesterday I was shooting a G19 and a G30. (9mm vs .45)

I can get nearly twice the number of rounds on target in a tighter group on the same target with the same time constraints as I can with a .45.

I can do it better with a .45 than I can a .40.

So I am more "effective" with a 9mm than I am with a .40.
 
Think of a slow moving bowling ball vs the velocity of a golf ball.

Which one is going to knock over the bowling pins?
 
Good analogy. Thanks.

When I bought my Sigma, I had a choice of 9 or 40 since they were the same price. I went with the 9 because I have another 9, my KT PF9. I figured that I'd keep it in the same family.

Now I was having second thoughts, conflicting pros and cons about the 9 and the 40 then I realized I can use +P and +P+ and increase my chance of SD. Am I correct about that? Higher pressure means more velocity/energy, right?
 
Now I was having second thoughts, conflicting pros and cons about the 9 and the 40 then I realized I can use +P and +P+ and increase my chance of SD. Am I correct about that? Higher pressure means more velocity/energy, right?
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Yes.

However, to start with make sure that you can make multiple fight stopping hits on one or more opponents on command from multiple positions from however you plan on having the gun stored/carrying it.

Then worry about your caliber.

Mindset
Tactics
Skill
lastly
Equipment

When you have gotten to the point that you can truly utilize the improved capability of the bowling ball, start throwing bowling balls. A gutter ball won't knock any pins down.:D
 
Now I was having second thoughts, conflicting pros and cons about the 9 and the 40 then I realized I can use +P and +P+ and increase my chance of SD. Am I correct about that? Higher pressure means more velocity/energy, right?
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Looks like you are correct that for self defense a +P or +P+ 9mm round can tend to be more effective than a non +P given the right bullet type. But you are a bit off base, I think, on the question of the pressure that a round operates at. The operating pressure of a round has no direct relationship to how "powerful" a round is.

The operating pressure is the pressure that is generated inside the case as the powder burns and gas expands inside. That pressure is governed by the type of powder used, the amount used, type of primer, etc. and the size of the case.

On the other hand when folks speak of the "power" of a round we are referring to the foot pounds of energy that the bullet has at it's disposal at the muzzle and downrange (a factor of velocity and bullet weight). Both the 9mm and the 40 S&W have the same operating pressures but the latter has a larger case and can contain more powder. So while they both have an average operating pressure of 35,000 psi the 40 S&W can send a heavier bullet down range faster than the 9mm can and generates more energy. So the 9mm can toss a 125 gr. +P bullet downrange at 1250 fps and generate 434 ft. pds. of energy (a Cor-Bon load) the 40 S&W can lob a 155 gr. bullet at 1200 fps. and produce 496 ft. pds of energy (a Speer load).

If we use momentum as a factor the 40SW is also more powerful.

The 45 Colt has a lower operating pressure (between 14,500 psi and 20,000 psi) than either the 9mm or the 40 but is a more powerful round than either. It can send a 225 gr. round out at 1200 fps in one load by Cor-Bon for 720 ft. pds. of energy. In a standard load, one from Speer, the old Colt round can send a 250 gr. GDHP out at 900 ft. per second. for 450 ft. pds of energy but a good deal more momentum than the 9 or the 40.

The higher pressure can be a factor in felt recoil.

Crow Hunter makes the good point though that in a small gun the heavier and snappier 40S&W may not be the best choice for some shooters in that quick and accurate shots may be easier with the 9mm and you also get an extra round or two.

Choosing a handgun is based on multiple considerations and so is choosing the round to go in it. Use what you shoot best of the service calibers.

tipoc
 
Yes. But personally I am not a fan. Especially in a SD/HD pistol. I believe 9mm is a better round for that situation. More rounds, less recoil, quicker shots. I could ramble on more. but that's IMHO. YMMV.
 
The operating pressure of a round has no direct relationship to how "powerful" a round is.
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The operating pressure has *everything* to do with how "powerful" a round is. The problem is that we're only ever given peak pressure, which isn't very helpful by itself.

If you could tell me what the pressure was at each portion of the barrel as the bullet moved through it, I could tell you the muzzle energy and the momentum of the bullet. It's the chamber/barrel pressure, acting on the cross-sectional area of the bullet as it moves through a known distance, that determines its energy and momentum.
 
Stand back!! There's science in this shtuff!
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I spent some time as a Uniform CSI, in fact I'm still certified as a LE CSI Instructor.

I learned Science stops when you hit the street, reality kicks in. Regardless of Newton's Physics, bullets do weird things on the street. Big ones, little ones, even the same bullets, bullets do their own thing.

The only thing you can predict is nothing is "always" nothing is "sure."
 
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