.357/9mm ballistics

[Flechette]

I got a question regarding the ballistics of these two cartridges.

.357 is considered more powerful than a 9mm, but with modern powders there are 9mm loads that approach a .357.

For example, on Ballistics By The Inch a 9mm, 4 inch barrel Cor Bon 125 gr load yields velocities of about 1200+ fps whereas .357 124gr is about the same.

.357 jumps to 1300-1400 for a 4 inch barrel but barrel lengths are measured differently for a revolver versus a auto so a 3 inch barrel is probably a better comparison.

However, if we go to heavier bullets a 147gr 9mm gives 900fps and change whereas a 158gr .357 gives 1100fps. Much better performance!

What's going on here? I would think that .357 would not have such good performance against the 9mm for heavier loads as more gas would be lost through the barrel cylinder gap. A heavier bullet means more time in the barrel and thus more time for gas to be lost. I would think that a 9mm has the advantage when using a heavier bullet but it is the exact opposite.

Another bit of weirdness, Ballistics By The Inch has a section of tests precisely on revolver cylinder gap. For the Cor Bon .357 125gr DPX (http://www.ballisticsbytheinch.com/corbon2.html) the load underperforms itself when using no cylinder gap!

How can the exact same load lose performance when there is no cylinder gap?

 

[Reefinmike]

Yes, +p+ 9mm loads can come close in energy to anemic 357 loads. Get some underwood, buffalo bore or load your own for true 357 magnum loads. I get a 158gr bullet going 1550fps from my 357 revolver. it leaves 9mm in the dust.

 

[TomJ]

Here's a comparison of Underwood's 124 grain +P+ 9mm Gold Dot to their 125 Grain 357 SIG Gold Dot. It's a difference of 175 FPS and 139 ft lbs. Too many manufacturers are watering down the 357 SIG and 10mm, which hardly makes them worth using. I stick with Underwood or Buffalo Bore, as they get the full potential out of those calibers.

Caliber: 9mm Luger
Bullet Weight: 124 Grains
Bullet Style: Speer Bonded Jacketed Hollow Point
Case Type: Ducta-Bright 7a Nickel Plated Brass
Muzzle Velocity: 1300 fps
Muzzle Energy: 465 ft. lbs.


Caliber: 357 Sig
Bullet Weight: 125 Grains
Bullet Style: Speer Bonded Jacketed Hollow Point
Case Type: Ducta-Bright 7a Nickel Plated Brass
Ballistics Information:
Muzzle Velocity: 1475 fps
Muzzle Energy: 604 ft. lbs.

 

[Flechette]

Yes, +p+ 9mm loads can come close in energy to anemic 357 loads. Get some underwood, buffalo bore or load your own for true 357 magnum loads. I get a 158gr bullet going 1550fps from my 357 revolver. it leaves 9mm in the dust.

How long is the barrel of your revolver to get that performance?

 

[Sunray]

Velocity is only part of the equation. Look at the energy graph too. Helps to read the whole site(including their disclaimer. FAQ's are kind of amusing as well.) too. Those guys aren't just filming themselves playing like some sites.

 

[jmr40]

The best 9mm loads from 4" barrels with 124 gr bullets will come within 50 fps of the best 125 gr 357 mag loads when fired from 4" barrels.

The best 155-180 gr 40 S&W loads from 4" barrels will come within 50 fps of the best 158-180 gr 357 mag loads when fired from 4" barrels.

For a 357 mag to have the same overall size as a 4" semi-auto it will have a 2-2.5" barrel and will have less bullet speed than 9mm or 40 S&W with comparable bullet weights.

If you start shooting 357 mag from 6-8" barrels it is in another league that 9mm or 40 S&W can't come close to.

I would think that a 9mm has the advantage when using a heavier bullet but it is the exact opposite.

Just a SWAG as I don't know for sure and I don't load for either. But a 357 mag case holds at about 2X as much powder. My guess is that more powder capacity combined with slower burning powders makes for a combo 9mm can't match with heavier bullets.

With any bullet weight 357 NEEDS more barrel to take advantage of the powder. The 357 mag was developed with an 8" barrel in mind. All of the published ballistics you see are from 8" barrels. It should come as no surprise that 2"-4" guns come up way short.

 

[Reefinmike]

The best 9mm loads from 4" barrels with 124 gr bullets will come within 50 fps of the best 125 gr 357 mag loads when fired from 4" barrels.

On ballistics by the inch, Im seeing a max of 1226 with a corbon 125gr +p 9mm from a 4" barrel. with 357 mag I'm seeing 1511 max fps with federal 125gr jhp. 357 has 50% more energy in that instance. Numbers you get from a 3" 357 mag are pretty similar to those from a 4" 9mm. 6" or longer 357 barrels blow 9mm out of the water. And yes, the numbers I listed in post #2 are from a 6" barrel.

Pretty sure OP is comparing 9mm luger and 357 magnum. Not sig. he mentions 158gr bullets...

 

[Rock185]

I don't pretend to understand all the variables. I have been chronographing for a good many years though, and one of the main things I've learned is not to try to predict what barrel length in this or that revolver or semi-auto will produce the higher velocity and energy with any given ammunition. One thing that initially surprised me was the generally higher velocities produced in revolvers as opposed to semi-autos with similar barrel lengths. I understand now, but it was initially counter intuitive that with the barrel/cylinder gap leaking high pressure gas, revolvers more often than not produced higher velocities than the semi-autos without such a gap.

For example; Federal 9BPLE 115 grain +P+ 9MM JHP chronographed in similar
barrel lengths, with and without barrel gaps:

Semi- auto 3 1/2" Bbl. = 1239 FPS
Revolver 3 1/16" " = 1313 FPS

Semi-auto 5" " = 1336 FPS
Revolver 4 5/8" " = 1372 FPS

Wish I had a .357 semi-auto to compare semi-auto and revolver velocities, but that I don't have.

 

[Reefinmike]

I don't pretend to understand all the variables. I have been chronographing for a good many years though, and one of the main things I've learned is not to try to predict what barrel length in this or that revolver or semi-auto will produce the higher velocity and energy with any given ammunition. One thing that initially surprised me was the generally higher velocities produced in revolvers as opposed to semi-autos with similar barrel lengths. I understand now, but it was initially counter intuitive that with the barrel/cylinder gap leaking high pressure gas, revolvers more often than not produced higher velocities than the semi-autos without such a gap.

For example; Federal 9BPLE 115 grain +P+ 9MM JHP chronographed in similar
barrel lengths, with and without barrel gaps:

Semi- auto 3 1/2" Bbl. = 1239 FPS
Revolver 3 1/16" " = 1313 FPS

Semi-auto 5" " = 1336 FPS
Revolver 4 5/8" " = 1372 FPS

Wish I had a .357 semi-auto to compare semi-auto and revolver velocities, but that I don't have.

revolver barrels are measured excluding the length of the cylinder. Auto barrel length is measured to include the length of the chamber. This is why you see greater velocities given "equal" barrel lengths pistol vs revolver.

 

[tipoc]

revolver barrels are measured excluding the length of the cylinder. Auto barrel length is measured to include the length of the chamber. This is why you see greater velocities given "equal" barrel lengths pistol vs revolver.

The above is true.

Wheelgun barrels are measured from the end of the barrel to the rear of the cylinder. This measurement excludes the cylinder including that portion that the bullet travels through to reach the barrel.

Pistol barrels are measured from the breech face to the end of the barrel. This includes the portion of the chamber where the bullet sits which is usually about the length of the case.

So a 4" pistol barrel is often 3.5" long or so (subtracting the chamber which varies in length with caliber and is the length of the case) and a 4" revolver barrel 4.5" long (or a tad less) if we include that portion of the cylinder that is in front of where the case rests in the chamber.

It's also true that you don't lose much to the barrel cylinder gap, often less than 25 fps.

Alot of rounds overlap in power. It's a common thing. But the .357 Magnum will always be a more powerful round than the 9mm. Even if, in the lesser loads for the 357, there is overlap. A look at BBTI will show you that.

tipoc

 

[suemarkp]

There are two factors to cartridge performance -- pressure rating and powder capacity. The 9mm and 357 magnum have very similar pressure ratings. But the 357 has much more powder capacity.

Powder capacity wins out for maximum velocity since pressures are equal. With light bullets and slow powders in the 357, you'll easily exceed the 9mm. But you're going to get a huge muzzle fireball.

The more interesting comparison is 38 special to 9mm. The 38 runs at half the pressure of 9mm, so you have to stuff the 38 with slow powder to approach 9mm performance. With heavy bullets, this gets easier since the 9mm really runs out of powder space when bullet weight gets over 150 grains.

Comparing two guns is never an apples to apples comparison. Even two identical guns can have different barrel friction. But when you have different barrel makes (e.g. diameter, rifling style, throat lengths, etc), the same load can be significantly different in velocity with the same length barrel. So doing a 9mm to 357 comparison is difficult to do (different barrel makes and calibers) unless you average it out over a few different barrel makes. You can always cherry pick your results to show how one is better than the other.

 

[Panzerschwein]

Yes, +p+ 9mm loads can come close in energy to anemic 357 loads. Get some underwood, buffalo bore or load your own for true 357 magnum loads. I get a 158gr bullet going 1550fps from my 357 revolver. it leaves 9mm in the dust.

Nuff said.

Really, if you're going to compare full end 9mm loads, also compare it to full end .357 magnum loads.

I think you'll find the .357 kicks the 9mms butt six way to Sunday.

 

[olafhardtB]

357 is better, that is written in stone.

 

[wanderinwalker]

There are two factors to cartridge performance -- pressure rating and powder capacity. The 9mm and 357 magnum have very similar pressure ratings. But the 357 has much more powder capacity.

Quoted for truth. Or as they say in the hot-rod engine world, "There's no replacement for displacement."

To draw an analogy: The 9mm is a turbo 2.0L 4-cylinder. The .357 Magnum is a large-displacement V-8. You can get pretty good numbers out of the 9mm but at the end of the day, if you push the bigger case just as hard, it's going to beat the little one.

Real chronograph numbers gave me 1270-fps for Winchester Ranger 127gr +P+ 9mm in a 4.5" Glock 17. A 4" barrel S&W 586 (.357 Magnum revolver) averaged 1450-fps with Remington UMC 125gr JSP .357 Magnum ammo. Keep in mind that's a 9mm load that is quite hot, as in few manufacturers will warranty their pistols if they know you're shooting that stuff. Whereas the .357 load is a standard loading, nothing particularly noteworthy.

In the same vein, it's easy to drive 158gr bullets over 1200-fps with the same .357 revolver. No 9mm Luger or NATO loading can come close to that number. The little 9x19mm case just can't burn enough powder to generate the gas volume to do that much work. (Actually, a 158gr .358" bullet is about as long as an empty 9mm case.)

And after saying all of that, I must add that 9mm and .357 Magnum are my favorite centerfire handgun rounds.

 

[8ring]

.357 magnums have more power because the casings have a much greater powder capacity than a 9mm. .357 magnums can hold 12-14 or more grains of slow-burning powder that creates a lot more hot expanding gases to propel the bullet.

125gr .357s can go much faster than 124gr 9mms. My favorite factory .357 load is the Remington-UMC 125gr Jacketed soft-point. These averaged a bit above 1,600 fps out of my old Ruger GP100 with a 6" barrel. I'll chrono these loads soon out of my new GP100 with a 4.2" barrel, but I expect that they will run between 1,400 and 1,500 fps.

A 9mm in a similar length barrel simply would never reach those velocities.

 

[hdwhit]

What's going on here? I would think that .357 would not have such good performance against the 9mm for heavier loads as more gas would be lost through the barrel cylinder gap.

There are a lot of variables in play here; weight of the bullet, force of the primer, speed of the powder, size of the cylinder gap, etc. that are really beyond a simple posting but I will point out that in a well fitted revolver, the cylinder gap is small and a fluid (the gasses produced by a smokeless propellant are governed by the rules of fluid mechanics) in turbulent flow does not readily pass through a narrow opening, so the losses would be expected to be rather modest.

Depending on the initial acceleration imparted by the ignition of the primer and the speed of the propellant's combustion, much of the bullet's acceleration may have been achieved by the time it's base clears the gap.

A heavier bullet means more time in the barrel and thus more time for gas to be lost.

The length of time the bullet is in the barrel is dependent upon a number of factors including the actual diameter of the bullet, the hardness of the bullet, the force of the primer, the speed of the powder, etc. A heavier bullet given a higher initial acceleration by a more forceful magnum primer continued by a fast burning powder might actually spend less time in the barrel than a lighter bullet given less initial acceleration by a standard primer and a slow burning powder.

For the Cor Bon .357 125gr DPX ... the load underperforms itself when using no cylinder gap!

Look at the graph carefully. With a 5 inch barrel, the round suddenly "jumps up" in velocity with a cylinder gap before settling back down. Without the tester providing some explanation for their data, the 5 inch readings appear to be anomalies probably attributable to experimental error. The fact that graphs for the Black Hills .357 158 gr load showed a sudden jump in a 16 inch no-gap barrel and the Mag Tech .38 Special 125 grain load showed a sudden jump for 7 and 8 inch no-gap barrels and the Cor-Bon .38 Special 125 grain load showed a sudden drop in a 16 inch barrel strongly suggesting the experimenters may have gathered some bad data.

But if we assume the testers were careful, there is no error and the Corbon load has been somehow optimized for 5 inch barrels, then the round fired with a gap only "outperforms" the "no-gap" round when then gap is 1/1000 inch and then only out of 2, 3 and 5 inch barrels. And this result goes back to what I was discussing, above, where the initial acceleration imparted by the primer combined with the continued acceleration from the burning propellant imparted before the base of the bullet clears the gap accounts for most of the performance.