9mm +P+ vs .357 mag

A projectile of the same weight, same profile same "caliber" going the same FPS doesn't care what gun it was shot from and barrel length needs to be the same.

Keep in mind that a 9mm +P+ is not a standard load.

Your chrono should be at least 10 feet not five.

1357 with a 125 grain .357 doesn't seem hot to me at all, I load 158 grain faster than that. (Edit:. If for some reason thought you had a 6", not a 4". Dunno what my loads do in a 4")

But yes, at the same relative speed the bullets will likely function nearly the same between the two platforms, just with less recoil out of the 9mm (likely)

As others have said if you move the same projectile the same speed it doesn't matter what platform is propelling it. That's a fairly standard 357 mag load, though - some of the boutique loads can go quite a bit faster out of a 4" barrel.

The 9mm vs 357 mag debate is kind of funny. In some scenarios they're pretty close, in others the 357 can be quite a bit hotter - relatively speaking. We're talking handgun rounds so both are pretty tepid in the overall scheme of firearms.

Typetwelve said:

Long story short, running some sets, my chrono reported that 5' from muzzle, the 9mm was clocking at an average of 1335 fps, the 357 at 1357. I understand that there is a 10 grain difference in weight, but am I to understand that all things being equal, I should expect similar performance from similar projectiles? If I load some 115g XTP projectiles to the 1300 fps range in 9mm, will this pretty much be toe to toe with what those .357 rounds can do?

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I believe in the bigger through hole theory of lethality, though it is not expressed in these terms. That is the most lethal cartridge is the one that makes the biggest through hole. So, what is the target, which would define both depth and tissue hardness? I assume you are thinking of the cartridge in terms of self defense against humans. That would fix cross section, depth, and hardness.

As to what makes the better self defense bullet, that is not something that a debate on weight, diameter, and velocity will determine. The real world is far more complicated and unpredictable. Only tests in real world will provide guidance, and we are lucky that Luckygunner has posted the expansion and depth of various 357 bullets and 9mm bullets. And based on these charts, the biggest hole is highly defendant on bullet construction. Some bullets don't expand at all.

38 Special and 357 expansion in ballistic gel

https://www.luckygunner.com/labs/revolver-ballistics-test/#357mag

9mm

https://www.luckygunner.com/labs/self-defense-ammo-ballistic-tests/#9mm

The "standard" 357 magnum load with a 125 grain bullet is 1450 fps from a 4" barrel, so those Hornady's are not considered a full powered load.

Hornady lists that load at 1500 fps from a 8" barrel, which is slow for an 8" barrel.
https://www.hornady.com/ammunition/handgun/357-mag-125-gr-xtp-american-gunner#!/

Keep in mind that a 9mm +P+ is not a standard load.

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It’s not even a known.
SAAMI 9mm pressure is 35,000, +P is 38,500, they have no standard for +P+. So anything from 38,501 to kaboom is +P+.

Typetwelve said:

I understand that there is a 10 grain difference in weight, but am I to understand that all things being equal, I should expect similar performance from similar projectiles?

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Yes. Pretty simple really. If two bullets of the same design and weight are going the same speed, they'll perform similarly. Doesn't matter if they were pushed into the chamber by a spring or rotated into place.

Possibly unrelated topic but also remember that auto and revolver barrel length is measured differently and revolvers lose some gas via the cylinder gap.

357’s today are neutered from what they used to be. The original SAAMI spec was 43,500psi. For safety since there are various ages and types of guns chambered in 357 they changed it to 35,000.

So due to manufacturing regulations they aren’t able to benefit from their case capacity. If you handload I’d say you can easily surpass the +p+.

But I do agree today with factory ammo, especially in a short barrel I’ll take the 9mm and leave the muzzle blast of the 357 at home

fxvr5 said:

The "standard" 357 magnum load with a 125 grain bullet is 1450 fps from a 4" barrel, so those Hornady's are not considered a full powered load.

Hornady lists that load at 1500 fps from a 8" barrel, which is slow for an 8" barrel.
https://www.hornady.com/ammunition/handgun/357-mag-125-gr-xtp-american-gunner#!/

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Well this is what I got from a six inch barrel. Real world values are very different from manufacturer's. I disliked the forcing cone erosion and huge fireballs I got with 125's, but I shot thousands. I am surprised that this is the only chronograph data I have on 125's in the 357. It would have been slower in a four inch barrel.

S&W M586 Blue Steel, 6" Barrel

125 gr JHP Federal Hi Shok Factory
13 Aug 2018 T = 92 ° F

Ave Vel = 1434
Std Dev = 30
ES = 78.26
High = 1468
Low = 1390
N = 6
excellent accuracy at 25 yards

Slamfire said:

Well this is what I got from a six inch barrel. Real world values are very different from manufacturer's. I disliked the forcing cone erosion and huge fireballs I got with 125's, but I shot thousands. I am surprised that this is the only chronograph data I have on 125's in the 357. It would have been slower in a four inch barrel.

S&W M586 Blue Steel, 6" Barrel

125 gr JHP Federal Hi Shok Factory
13 Aug 2018 T = 92 ° F

Ave Vel = 1434
Std Dev = 30
ES = 78.26
High = 1468
Low = 1390
N = 6
excellent accuracy at 25 yards

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And different guns (barrels) shoot them at different speeds. Check the catalog number of your Federal load (if you still have it). The 125 grain I see in their 2019 catalog C357B shows 1440 fps from a 4" vented barrel.

I've found the Remington 125 SJHP 357 Mag (#R357M1) to be very close to their advertised 1450 fps from a 4" vented barrel. It clocks at 1255 fps from a 2" Colt Magnum Carry, 1465 fps from a 4" S&W 686, and 1739 fps from a Ruger 6.5" Blackhawk.

I also tried some Federal 158 JHP (C357E). It's rated at 1240 fps from a 4" barrel. My sample ran 1415 fps from the Ruger 6.5" barrel.

In fact most of the factory ammo I shoot has been a good match with their published data. There have been some exceptions.

You won't have any issues with getting 125 gr +p load to shoot 1250-1300 fps from a 4.5" or 5" 9mm barrel. That is only about 50 fps slower than typical 125 gr 357 mag loads from 4" barrels and about 50 fps faster than 3" 357 mag barrels. Bear in mind that a 4.5" 9mm pistol is about the same overall length as a 3" barreled revolver. From 8" test barrels 357 loads will get 1500 fps, and there are some hotter 357 loads out there that will slightly beat those speeds even from 3" and 4" barrels.

But real world speeds of 1300-1350 fps with 125 gr 357 mag loads is what earned the 357's reputation as a fight stopper. In the real world 9mm just ain't that far behind in guns of comparable size.

jmr40 said:

You won't have any issues with getting 125 gr +p load to shoot 1250-1300 fps from a 4.5" or 5" 9mm barrel. That is only about 50 fps slower than typical 125 gr 357 mag loads from 4" barrels and about 50 fps faster than 3" 357 mag barrels. Bear in mind that a 4.5" 9mm pistol is about the same overall length as a 3" barreled revolver. From 8" test barrels 357 loads will get 1500 fps, and there are some hotter 357 loads out there that will slightly beat those speeds even from 3" and 4" barrels.

But real world speeds of 1300-1350 fps with 125 gr 357 mag loads is what earned the 357's reputation as a fight stopper. In the real world 9mm just ain't that far behind in guns of comparable size.

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I imagine from a 8" test barrel that some loads, like the Remington 125 SJHP will easily hit 1800+ fps. I got 1739 fps from a 6.5" Ruger Blackhawk.

Different guns will give different results. Some chrono results that may be of interest. Ran these over a new Labradar a couple of months ago.

For Information Only, Use at Your Own Risk

Labradar Muzzle Velocity (familiarization run)
60 Deg F
S&W M66-8 2.75" .357 Mag

130gr Fed Hydra-Shok JHP "Personal Defense" PD357HS2 H …….. 1,416 fps avg (84 fps ES) -- two rounds
140gr Underwood Xtreme Penetrator (Philips head mono metal).. 1,422 fps avg ( 5 fps ES) -- two rounds
158gr Horn Xtp - 15.0gr A2400 Std small pistol, new Starline...… 1,316 fps avg (49 fps ES) -- six rounds
165gr CSWCGC (358156) - 13.0gr A2400 New Starline ...… 1,070 fps avg (49 fps ES) -- six rounds
180gr Buff Bore …………………………………………………………………………….. 1,312 fps avg ( 6 fps ES) -- two rounds
185gr LFNGC (Beartooth), 15.0gr Lil'Gun, CCI 400 New Starline.. 1,228 fps avg (14 fps ES) – two rounds
200gr WLNGC (leadheads), 13.4gr H110, Fed 205, New Starline.. 1,102 fps avg ( 4 fps ES) – two rounds
200gr WLNGC (leadheads), 14.4gr H110, Fed 205, New Starline.. 1,155 fps avg ( 2 fps ES) – two rounds
(purported to be the “Doubletap” load info)

200gr WLNGC (leadheads) handload with Lil Gun ………………………. 1,266 fps avg ( 2 fps ES) -- two rounds
Load data not given -- maybe too much of a good thing. Spent cases fell from chambers, and no obvious signs of over pressure. Recoil was heavy. Don't even know if this stabilizes.


If even needed, I would limit useage of the 180, 185, and 200gr loads in J & K Frame guns


Also ran two Buff Bore 180s thru 16" Rossi M92 carbine ……………. 1,894 fps avg ( 6 fps ES) -- two rounds

Larger sample would change results but probably not a great deal.


Previous results in a couple of 9mms with an old optical chrono at 15 ft from muzzle

3.5" Kahr CW9 Win 127gr +P+ --------- 1,190 fps (65 deg F)
4.0" FNX Cor Bon 115gr ------------------ 1,340 fps (65 deg F)
3.8" CZ Buff Bore 147gr +P--------------- 1,130 fps (65 deg F)

Only point -- different guns, different results, sometimes substantial.

FWIW,

Paul

JR24 said:

1357 with a 125 grain .357 doesn't seem hot to me at all...

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I agree. On my chrono, from a 5" barrel, .357 Magnum can propel a 125 gr. bullet 1700 fps. Lucky Gunner clocked 125 gr. at 1644 fps from a 4.2" barrel on a GP100 in their ballistics tests. Those are real-world tests with an actual gun with a cylinder gap -- not just a test barrel.

9mm +P+ isn't a specification, but an indication of something above +P spec. Even if it were loaded to 100kpsi, 9x19mm is not going to match the best performance (in terms of velocity or energy, but keep in mind ammunition performance is a lot more than what we measure as velocity and energy. ) of .357 Magnum at standard pressures because the case volume won't allow enough powder to burn over a long enough duration. To the OP's question, the answer is no, 9mm+P+ is not a "match" for .357 Magnum.

Increasing maximum pressure alone is an inefficient route to increasing velocity. Burning powder doesn't just produce pressure. It produces pressure for a duration of time. A +P+ designation might allow the cartridge to generate a maximum of 41,000 psi instead of 35,000 psi, but the small volume of powder in a 9x19mm case can only produce that pressure for less than a tenth of a millisecond. With a 9mm +P+, we'd see a steep spike to some high pressure (probably close to 40kpsi) but then it would drop off to as little as 5000psi after only a tenth of a millisecond. When the bullet base exits the muzzle, the pressure would be lower still. With a .357 Magnum using a large mass of slower powder like H110, we'd see the pressure gradually rise to the standard 35,000 psi after 0.2ms and gradually drop from there so the bullet leaves the muzzle 0.43 milliseconds after the start with still over 10,000 psi behind it. Imagine pressure graphed as a curve across a time-axis. The 9mm+P+ is going to have a steep spike and drop. The .357 Magnum is going to have a large, wide hump. Velocity is going to be made by the area under the curve. If the curve is very steep for a very short amount of time, it's going to have to go tremendously high to have the same area under the curve as a wide hump. But the only way to get that wide hump is with a large mass of slow burning powder, and that large mass of slow burning powder usually fills a .357 Magnum case and will not fit into a 9x19mm case, at least not with current powder technology.

In my mind, the real beauty of .357 Magnum is that the large case allows room for a variety of options. Besides fitting more slow burning powder, it can also fit longer, heavier bullets. It can fit bullets of unusual designs and shapes, and generally doesn't have to work on a feed ramp, but also has a small enough diameter that more of them fit into a revolver cylinder (than .45 for example). Short cartridges like the 9x19mm really only do one thing well: fit into handgrips.

The 9mm can produce impressive performance in the right guns when loaded for 9 Major performance. It's not that difficult to get a 124/5 grain bullet to 1400+ fps. I've fired a commercially available 9 Major load that achieved 1494 fps with a 124 grain bullet from a 4.6" barrel. That puts it in the same ballpark as most commercial 357 Magnum loads. Some boutique 357 load will be faster, but the 9mm can hold its own if loaded right. I'm not suggesting people here do that. It's only safe in a gun built to handle the pressure that 9 Major will produce.

Bullet weight and velocity are, of course, two factors. Bullet configuration is another. Pistols that shoot 9mm bullets are great if they can handle the +P+ pressures (and I have a Taurus PT92, a S&W 659 and a 5906, the latter two which should work fine, and the Taurus I'm unsure of, but it should handle it). But just because a 9mm can attain magnum velocities, or near magnum velocities, doesn't mean the bullets will peel back and expand like .357 magnum bullets.

Stopping power is more than just the size of the entry hole (I'd think the exit hole would be more indicative of power than the hole going in). The 9mm is no slouch as far as power is concerned, but if hiking, camping, fishing or hunting, I'd prefer the .357, which I consider a superb outdoor caliber. The 9mm certainly has the power to punch its way into a dangerous animal, and it certainly had the power to drill into the cranial cavity of a black bear or to put down feral dogs, but I still would favor carrying my .357 Security-Six (my 6-inch model still weighs less than the 4-inch GP-100).



I think the .357 magnum is one of the most underrated calibers on the market, and if David Mann had had one in the movie Duel, it most likely would have been a very short movie. The 9mm also is underrated and has a very flat trajectory, but is hobbled by its reputation as a poor performer. I'm sure modern ammo design has fixed this, but the military still is required to use the full metal jacket, and even hollowpoints don't tend to expand as well as the .357 SJHPs.
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IMO you're comparing apples with oranges in a way. You're comparing a +P+ in a 9mm that is putting extra stress on the gun with a 627 that can eat standard 357s for a long time.

I'm not a fan of +P and +P+. I will use +P in K frame or larger 38s and +P+ 38s in 357 guns. That's about it. If I need more power I use more gun.

All the extra "boiler room" of a .357 case does make a difference. I load my own 9mm Major ammo, which means going beyond book maximums. I'm comfortable using that out of my race gun that has a big old compensator on the front - which slows slide velocity quite dramatically (it also makes the gun shoot "flat"). But primers are generally pretty flat, and without the comp I'd be beating the hell out of the gun. .357 can get to the same power factor with no excursions beyond published loads required.

ATLDave said:

and without the comp I'd be beating the hell out of the gun.

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9 Major has the same recoil as a 9X23 Winchester, 357 SIG, 40 S&W or 45 Auto. None of these beat the hell out of a gun. Just spring the gun appropriately and you're good to go.

fxvr5 said:

9 Major has the same recoil as a 9X23 Winchester, 357 SIG, 40 S&W or 45 Auto. None of these beat the hell out of a gun. Just spring the gun appropriately and you're good to go.

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Springs don't have nearly as much impact on slide velocity as most people assume. https://www.shootingtimes.com/editorial/recoil-spring-rate-affects-timing/99604

ATLDave said:

Springs don't have nearly as much impact on slide velocity as most people assume. https://www.shootingtimes.com/editorial/recoil-spring-rate-affects-timing/99604

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The point is that 9 Major won't do anything worse than the calibers I mentioned previously.

labnoti said:

Short cartridges like the 9x19mm really only do one thing well: fit into handgrips.

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Very well said!