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Discussion Starter #1
According to SAAMI specs the 357 magnum operating pressure was 45000 CUP while the 9mm Luger was 33000 CUP. The magnum having approximately 50% more pressure. When we look at the piezo pressures in 2015 we find the 9mm Luger at 35000 PSI and the 357 Magnum reduced to 35000 PSI or the same as a 9mm Luger. This reduction was called for by at least three of the manufacturers of guns with side plates because the higher pressure rounds were causing problems in their lighter revolvers and rather than build stronger guns they had the pressures lowered. I haven’t been able to find copies of those communications but I did find the original data being used, unchanged, in the European market.


According to the C.I.P. rulings, the .357 Magnum cartridge case can handle up to 300.00*MPa (43,511*psi) Pmax piezo pressure. In C.I.P.-regulated countries every pistol cartridge combination has to be proofed at 130% of this maximum C.I.P. pressure to certify for sale to consumers. This means that .357 Magnum chambered arms in C.I.P. regulated countries are currently (2018) proof tested at 390.00*MPa (56,565*psi) PE piezo pressure.

The 9×19mm Parabellum was introduced in the year (1902) but was originally designed for smokeless powder, and for higher pressures (235.00*MPa (34,084*psi) Pmax piezo pressure).
You will notice the the 357 has approximately 50% more pressure.

At least one of the American reloading manuals are still using this data for their load information, Sierra. I have been using this data to load my 357 Magnums from nearly the very start of my reloading career 45 years ago. They are still operating with fine accuracy after the targets, competitions, practice for the competitions, training, hunting and just plinking all using the same load. According to almost all the other manuals I am shooting 1.5 grain overloads yet the cases fall out of the cylinder under their own weight and I have never had to take my gun to a smith for repair or tuning. Not bad for a gun that has had well over 30,000 rounds fired through it.

I believe most of the ammunition for the 357 is neutered to the reduced pressure and might be the reason there is so much talk about the 9mm being as powerful as the 357. What I do know is that I have been using over 19 grains of H110 with a 140 grain bullet that gives me 1599 fps from a six inch barrel. This is not the hottest load listed in the Sierra manual but it is the most accurate in my gun. The highest loads provided muzzle velocities of 1602 and 1619 fps and also dropped freely from the cylinder. Accuracy fell off with those loads. I am not a velocity reloader as I load for accuracy whether in my pistols or rifles. H110 has given me the very best accuracy at close to maximum loads and when shooting out to 100 yards that was very important. The velocity was a plus because I didn't have to adjust my sights during the match.

I have heard all the explanations of why the piezo pressures are so different from the CUP pressures but the real answer is that some gun makers didn't want to make stronger guns so SAAMI was petitioned to drop the pressures. CIP was not affected by the politics and left it where it should be.
 

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I had read at one time about the downloading of the 357. I never really thought much about it until out shooting with my Uncle. He had an old 3 screw 357 Black Hawk and asked if I wanted to shoot it. He drug out some old green box Remington shells from the 50's/60's. I don't know when they changed the pressures, but those old shells had a lot more snap than the 357's I was used to shooting.

I always suspected that those older Remingtons were loaded to the higher pressures. What year did the official load change?

Also, I am going to have to check to see if my Sierra manual shows hotter loads?

I would not think those hotter loads would be an issue in a Marlin. I am getting ready to try some Lil Gun in my 1894 357. It is supposed to be the ticket with 158 gr bullets in a carbine length barrel.
 

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So, SAAMI, who sets the "standards" (or unofficial industry standard recommendations) for all firearms' pressures, sizes etc., caved to gun manufacturers who didn't want to make "stronger guns"? :confused: No offence, but I don't believe it.
 

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Discussion Starter #4 (Edited)
mikld,
You don't have to believe it. Can you come up with any reason why the pressures of the 357 were dropped by 50%?
Why would the CIP pressures which typically agree with SAAMI maintain the 50% difference between the 9mm and the 357 while SAAMI dropped the pressures down?
The fact that the the pressures dropped in the USA but remained high in Europe shows that something happened that was independent of the cartridge. Elmer Keith would be ashamed to see what they did to his cartridge.;)

SAAMI doesn't set the pressures, the manufacturers set the pressures. SAAMI just publishes those pressures as a guide for the rest of the cartridge and gun manufacturers to use in the manufacture of guns and ammo.
 

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The Hog Whisperer (Administrator)
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Paul,

Hate to derail a good rant/conspiracy theory, but you are very mistaken if you think that CUP = PSI. In some it might be higher, some lower, and by random chance, in some it might well be the same. Plus CUP is notoriously inaccurate, even if you are comparing CUP from one source, to CUP from another, with the same reference ammo, and calibrated test cylinders.

Did it go down? Probably. By how much? No one knows, nor can anyone know for sure, much more than an educated guess. That's just a fact; you can spin that any way you like.
 

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Discussion Starter #6 (Edited)
MikeG,
I am not questioning the accuracy of CUP or even of the piezo system.
What I am presenting is relative comparisons within the systems of two separate sets of data.
I am proposing that while the data from SAAMI changed the pressure ratio between the 9mm and 357 from 50% advantage to the 357 to equal pressures between the two while the same measurement system in European countries shows the pressure ratio continues.
Either the SAAMI method has a big flaw with only a few magnum cartridges or the CIP piezo system is valid and the pressures were dropped radically in the USA. Both systems use the piezo pressure transducer and both have similar pressures for the 9mm but when listing the pressures for the 357 SAAMI says it is the same as a 9mm and CIP says the magnum pressure is 50% more.
That tells me that the pressure of the 357 was dropped >9000 PSI by SAAMI. That is a big jump in any system but in the digital world it is only possible if the pressures were reduced.
 

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The Hog Whisperer (Administrator)
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You're still making some huge assumptions. It is bad enough trying to compare CUP to PSI for one cartridge. Throwing in another cartridge is hopeless! If you think that CUP to PSI comparisons across cartridges tell you anything, then you are deluding yourself.

Go look up charts that have been published where CUP and PSI have been directly measured at the same time. The differences are all over the place!

You don't know how much pressures dropped when SAAMI went to PSI from CUP, unless you had some of the old reference ammunition around, and fired it in a barrel that could measure PSI. The short answer is, no one really knows. You're deluding yourself if you think you can reverse-engineer this, with least bit of hope of getting accurate answers.
 

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The Shadow (Super Mod)
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You need to read more on the differences(SAAMI vs CIP).

First of all, the reduction by your own numbers isn't 50%. 50% would put the 357 up in the high 49,000 psi range.
Secondly, the 9mm wasn't designed to 35,000 psi. Maybe it was designed to 35,000 CUP, I'd have to double check; but it's possible it was designed in the LUP era.

The "difference" you think you've stumbled upon, isn't.
This is the same as the old argument about the 223 Vs. 5.56. UncleNick has a wonderful explanation in another thread, but to reiterate:
"How come muh 223 can only shoot 55,000 psi, but the CIP says it can shoot 62,000 psi? They is a conspiracy!!"
No, there isn't; the measurement systems are different.

SAAMI uses conformal transducers, at a certain location around the brass. CIP does not use conformal transducers, and they drill a hole for measurement into a different location on the brass. Different measurement systems in different locations give different results.
The bulk of the reference ammo used by the proof houses used for certification by CIP come from (the answer is on their website, FYI) SAAMI manufacturers. The same ammo had different results, when you measure differently.

Pretending for a moment: let's say that in fact you could magically correlate the data from the two different systems. Using the differences from the 223/5.56, your 357 is back up above 42,000 psi. Not incidentally, no doubt you noticed where many CIP ratings are lower than SAAMI; but chose to ignore that for the conspiracy. Which speaks to why MikeG said you can't simply correlate one thing to another.

Did SAAMI drop pressures? As Mike said, who knows. What you are referencing, happened in roughly the early 90's when they switched from crushers to Conformal transducers. That's not simply a minor side note.
But back to pretending that systems correlate simplistically, that would be a reduction of approximately 20%, not the 50% you keep claiming.

Cheers
 

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My two cents on this discussion:
SAAMI TEST METHOD differs from CIP TEST METHOD with significant differences that 'color' the results.
SAAMI publishes consensus Recommended Practices and values.
CIP Standards and Methods/practices are legally imposed requirements in signatory countries.

as stated by others
SAAMI uses Conformal Piezo Transducers which do not require 'drilling' cartridge walls.
CIP does use 'drilled wall cartridges in its' test processes, removing wall strength and elasticity from the measurements.
This indicates that SAAMI is measuring a PMAX MAP that is 'reduced' by the strength and elasticity of the cartridge case.
Further, SAAMI measures at a distance from the cartridge base that differs from the distance used by CIP Standards and processes for measurements.

Personally I do not like at least one SAAMI and CIP measurement process = Both test the .25ACP/ 6,35 Browning ammo with a ~6 inch long Test Barrel rather than a ~24 inch Test Barrel, which has "hobbled' this cartridge's development compared to .22Long Rifle Rim Fire ammo.

Just my opinions,
Chev. William

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The Hog Whisperer (Administrator)
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How about this as a metaphor......

CUP is like everyone showing up with a homemade yardstick, that happens to be equal to three lengths of what each (different) person's feet end up being.

PSI, you get a calibrated micrometer and reference standard. Which one do you think might yield more accurate, repeatable measurements, to the thousandth of a inch? :confused:
 

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Elk Whisperer (Super Moderator)
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However the pressure of .357 magnum ammo is measured, MY ammo is only shared between MY three .357's and all boxes are clearly marked and in my load notes as to which gun(s) not to shoot the "hot stuff" in.

As to the yardstick theory, not even any two of those hardware store freebies are the same as my Starrett three foot straight edge ;)

Anyways

RJ
 

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I didn't think the OP was comparing CUP to PSI, rather he was comparing 357 Magnums as they were to what they are now. And anyone who says the Magnum (and the 38 Special) didn't drop in performance in the '90s either isn't old enough to know what the older ammunition was like, or didn't shoot much of it back in it's glory days.

when I came on the handgun scene standard 158g RNL 38 Specials ran about 850 fps from a 4" barrel. Today that same bullet averages more like 750 fps. 158g +P 38 Specials used to be 900 fps from a 4" barrel. The ones I've chronographed in the last 10 years ran more like 800 fps. That's not a conspiracy theory, that's just facts.

YMMV,
Dave
 

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As pointed out, there is no way to do a direct comparison between PSI, CUP and CIP. The difference between the old standard and the new is obvious though. The example I use for the .357 Magnum is Action Arms #9 load data. In the current Western Powders manuals, I believe the maximum load of AA#9 for a 158gr bullets is either 12.0 or 12.5gr. That is lower than the starting loads listed in the earlier manuals which show a maximum of 15.0gr. Since the new data uses the 35 kpsi standard, there is no question that the Magnum's performance has been watered down.
Folks can argue that the difference between the old SAAMI CUP standard and the new PSI is simply in the way the pressure is measured, but the load data itself says that isn't true. Why it was done, in my opinion, is that the original loads for the .357 were not compatible with the trend toward smaller, lighter revolvers both in durability and comfort.
Which is exactly why the cartridge was introduced in full size revolvers 90 years ago.
 

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The Shadow (Super Mod)
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I didn't think the OP was comparing CUP to PSI, rather he was comparing 357 Magnums as they were to what they are now. And anyone who says the Magnum (and the 38 Special) didn't drop in performance in the '90s either isn't old enough to know what the older ammunition was like, or didn't shoot much of it back in it's glory days.
That's not a conspiracy theory, that's just facts.

YMMV,
Dave

Yeah, he was; read what he wrote.

The "glory days" like when crushers said two loads were identical, but in reality they could vary by 20,000+ psi ; and we'd be unknowingly shooting proof loads?:rolleyes:


As pointed out, there is no way to do a direct comparison between PSI, CUP and CIP. The difference between the old standard and the new is obvious though. The example I use for the .357 Magnum is Action Arms #9 load data. In the current Western Powders manuals, I believe the maximum load of AA#9 for a 158gr bullets is either 12.0 or 12.5gr. That is lower than the starting loads listed in the earlier manuals which show a maximum of 15.0gr. Since the new data uses the 35 kpsi standard, there is no question that the Magnum's performance has been watered down.
Folks can argue that the difference between the old SAAMI CUP standard and the new PSI is simply in the way the pressure is measured, but the load data itself says that isn't true. Why it was done, in my opinion, is that the original loads for the .357 were not compatible with the trend toward smaller, lighter revolvers both in durability and comfort.
Which is exactly why the cartridge was introduced in full size revolvers 90 years ago.
Spend some time reading the SAAMI website, and do some reading about the wild inaccuracies of crushers. A lot of good info on that can easily be found on this website.... It's not opinion, and it's not new.
Then you may also realize that you further are mixing three separate powders up.
The Accurate Arms #9 was an Israeli defence contractors surplussed powder. Once that company went T.U. and it became just Accurate in Montana, they jumped continents to the French state owned Groupe SNPE. That is until the past several years when they silently switched again to General Dynamics powder, despite having an old and incorrect SDS from 2012 on the site.

If it's confusing to someone that differently sourced powders have different charge ranges, maybe simply buying ammo would be a better choice.

Cheers
 

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All of you who are discussing CUP vs PSI and SAAMI vs CIP are correct in that the OP was mixing, swapping and incorrectly looking at that information. I am an engineer and struggle going through the information and misinformation on the interweb. Unfortunately incorrect information on the Web is not always identified as such and can be found on very reputable sources.

But there is one question that is much simpler and has not really been addressed by the more learned of the group.

Did the industry, ammo manufacturers and SAAMI, reduce the performance of the 357 Magnum in the early 90's. Do you believe the performance of the 357 Magnum was reduced in the early 90's? That is my question.

I went back through Ken Walters book last night. This has a lot of his old articles. He wrote 3 articles on the 357 Mag, all before 1980. I meant to write down some of his information, but did not. The testing he did on factory ammo I believe shows increased velocity compared to what current publicized factory information shows. I need to gather more facts to back that statement up.
 

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I have 60 years of Shooters Bibles with factory ballistics tables in them all. The .357, 158 grain loads have been right at 1400 fps since the late 1930s. How fast the bullet leaves the only hole in the case is generally more accurate that measuring a copper crusher that by definition is being deformed AS the bullet is moving. Variations in readings are normal and usually large. I think SAAMI has done well in trying to standardize a more accurate method.

If you want the flash, crack, bang and velocity of 'old time' .357s just load up with a max charge of H-110 and you'll get it.
 

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The Shadow (Super Mod)
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But there is one question that is much simpler and has not really been addressed by the more learned of the group.

Did the industry, ammo manufacturers and SAAMI, reduce the performance of the 357 Magnum in the early 90's. Do you believe the performance of the 357 Magnum was reduced in the early 90's? That is my question.
.
Yes it was, in almost every response if you read them.



Paul,

Hate to derail a good rant/conspiracy theory, but you are very mistaken if you think that CUP = PSI. In some it might be higher, some lower, and by random chance, in some it might well be the same. Plus CUP is notoriously inaccurate...
Did it go down? Probably. By how much? No one knows, nor can anyone know for sure, much more than an educated guess. That's just a fact; you can spin that any way you like.
You're still making some huge assumptions. It is bad enough trying to compare CUP to PSI for one cartridge. Throwing in another cartridge is hopeless!

You don't know how much pressures dropped when SAAMI went to PSI from CUP, unless you had some of the old reference ammunition around, and fired it in a barrel that could measure PSI. The short answer is, no one really knows. You're deluding yourself if you think you can reverse-engineer this, with least bit of hope of getting accurate answers.
The "difference" you think you've stumbled upon, isn't.
This is the same as the old argument about the 223 Vs. 5.56.

Did SAAMI drop pressures? As Mike said, who knows. What you are referencing, happened in roughly the early 90's when they switched from crushers to Conformal transducers. That's not simply a minor side note.
But back to pretending that systems correlate simplistically, that would be a reduction of approximately 20%, not the 50% you keep claiming.

Cheers
How about this as a metaphor......

CUP is like everyone showing up with a homemade yardstick, that happens to be equal to three lengths of what each (different) person's feet end up being.

PSI, you get a calibrated micrometer and reference standard. Which one do you think might yield more accurate, repeatable measurements,
The "glory days" like when crushers said two loads were identical, but in reality they could vary by 20,000+ psi ; and we'd be unknowingly shooting proof loads?:rolleyes:

If it isn't yet painfully clear, I'll say it again.

Copper Units of Pressure(CUP) tell you how much a piece a copper got squished, that's it. It has zero; re-read that: ZERO connection to actual pressure.
33,000 CUP in one instance, might mean 35,000 PSI. In another instance, 33,000 CUP may actually be 58,000 PSI.

Comparing 35,000 CUP to 40,000 CUP tells you only slightly more than nothing. Because crushers don't react well to instantaneous impulses, and can have a splatter factor; you can get false "signs" all the time.

For a very real example, consider two loads. One which is very high pressure and uses a very fast powder. The other normal pressure using a normal powder. When using CUP, the normal pressure load would actually have time to fully deform the crusher. The high pressure fast burning powder wouldn't. Meaning you would rate the scary high pressure cartridge as lower pressure, that measurement system can't accurately report various burning rates, or pressures.

Let that soak in for a moment...

The 33,000 CUP load, is actually almost a proof load. What you tested and rated a 50,000 CUP load, was actually a middle of the road load. :eek:

Now knowing that, which did, does, and will happen when you use crushers.

Stop horsing around and tell me how much less pressure or performance that 33,000 CUP load is....:rolleyes::rolleyes:
 

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mikld,
You don't have to believe it. Can you come up with any reason why the pressures of the 357 were dropped by 50%?
Why would the CIP pressures which typically agree with SAAMI maintain the 50% difference between the 9mm and the 357 while SAAMI dropped the pressures down?
The fact that the the pressures dropped in the USA but remained high in Europe shows that something happened that was independent of the cartridge. Elmer Keith would be ashamed to see what they did to his cartridge.;)

SAAMI doesn't set the pressures, the manufacturers set the pressures. SAAMI just publishes those pressures as a guide for the rest of the cartridge and gun manufacturers to use in the manufacture of guns and ammo.
It's part of the anti-gun conspiracy (not to mention new, better, more accurate measuring techniques). Our foes are attacking ammo now in an effort to push more and more regulations and eventually stopping all gun sales. :rolleyes:
 

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Darkker

Thank you for the long explanation of what you already stated and what I already understood about the differences in the system. I was trying to avoid that by asking a very simple question.

Which according to you "Yes it was, in almost every response if you read them.". Which I read as yes, the performance of the 357 Magnum was reduced in the early 90's. Thank you for the answer.

If you would like to tell me difference between CUP and PSI in ammo testing again, I would be more than happy to read it. It is kind of a slow day.

Better yet, let's get into the the difference between where SAAMI and CIP place their pressure transducers on their test barrels and how that can effect the pressure reading.

P.S. It looks like we have already caused kdub to tap out.
 
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