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.

 

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"? No offence, but I don't believe it.

 

Somewhere I have an article that explains how CUP and PSI are very close but ONLY in straightwall cartridges. Based on my observations, I'm inclined to believe it. Folks that have read Elmer Keith might remember that much of his data was tested by HP White Labs and is expressed in PSI. I also agree with MikeG that CUP is notoriously inaccurate and there's really no way of knowing how much exactly the pressure changed. However, I do believe it was lowered. Maybe by default with more accurate pressure testing, maybe deliberately for the sake of a certain major manufacturer that still uses a +120yr old sideplate design. I don't think it was a whole **** of a lot and certainly not 50% but definitely at least a little lower. Further, I think a lot of modern factory ammo is loaded well below published maximums. I like to use Winchester white box .44Mag as an example. A 240gr at 1200fps. If both Keith and Brian Pearce report the 1200fps Keith .44Spl load as ~26,000psi (not CUP) then there's no way the WWB .44Mag load is anywhere near 36,000psi.




Well, SAAMI IS the industry. Not some government entity. So if enough of its members vote to make a change, they make a change.

 

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.

 

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.

 

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.

 

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.

 

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

 

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

.

 

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?

 

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

 

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

 

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?

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

 

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.

 

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.

 

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?

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.

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....

 

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.

 

Oh...… my head hurts!!

 

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.

 

Darkker

1) I was trying to avoid that by asking a very simple question.

2) 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.

3) 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.

1) It's not as simple as some would like to think
2) The CUP was reduced, indeed. What that doesn't tell you was whether the performance was reduced by a known amount.

Crushers are like measuring in "steps", and PSI is like measuring in "Feet".
My friend started high school at 5'2" tall, he graduated at 6'7" tall.
When we had to run laps on the football field, he had to run 3,000 steps when we started. By the time graduation came close he was only running 1,500 steps in the same amount of laps.

Does that mean the distance he traveled was reduced? No, the distance in an actual measurement, "feet", was not reduced. The distance in the arbitrary unit of "steps" was reduced, but that has nothing to do with actual distance. If you want to know a distance, telling someone 30 steps can mean lots of different measurements. Rather simplistic, but shows the point.

3) Not in a good place to verify, so don't use this as the absolute SAAMI location.
The conformal transducer used by SAAMI, goes against the case in the chamber some distance ahead of the case head. The case pushes against it. CIP drills a hole somewhere near the case mouth, and the gas pushes against the transducer.

If you're a car guy:
Horsepower can be measured at the crank on an engine stand. Or it can be measured at the rear wheels on a chassis Dyno. Lots of folks give you a "simple" answer like "drivetrain losses are only about 10-12%". The drivetrain losses between an F550 & a Honda Accord will be much different.
Both systems are accurate, but measure things differently, at different locations.

Cheers

 

First; a 5.56 cartridge fired in a .223 chamber will produce more pressure than a .223 round. There is a BIG difference in the chambers of the two cartridges. The throat of the chamber in a .223 is shorter than the throat in a 5.56 chamber.

Second; I never compared CUP to PSI. I compared the relative CUP in two cases to the relative pressures in PSI.
Third; I compared the relative pressures in SAAMI piezo system to the relative pressures in the CIP pressure system.
I never compared the SAMMI pressures to the CIP pressures - just the relative pressures of each system to a known value.
The 9mm was never loaded with black powder it was designed for and used smokeless powder in higher pressures than the "standard loads" of the period. Guessing that it was developed using LUP is a statement that is founded in a lack of education and knowledge. Also CIP measurements are taken just in front of the case mouth so no holes are drilled except in the chamber just in front of the case.

Let me simplify this:
I have two cartridges. One is known to be higher pressure than the other and is designated "Magnum" we will call that cartridge "M". One cartridge is a modern high pressure cartridge in a "normal" pressure range. We will call that cartridge "N". The measured ratio between the two cartridges is simply "R" which equals M/N.
Now we have three measurements of the two cartridges.
We have "C" that shows R=M/N = 1.5
We have "D" that shows R=M/N = 1.5
and we have "E" that shows R=M/N = 1.0

Since we know that M is greater than N it is impossible for M/N to equal 1. or we have to assume that the standards for the pressure of M to deviate in test E.
Notice that I am not comparing the measurement systems but rather the resulting ratios of each system with the ratios of the other systems.

Measuring the weights of two melons which weigh 2.2 and 1.1 pounds The same can be done:
In the first test C; BM (big melon) weighs 1 and SM (small melon) weighs 0.5. the ratio is 1:0.5 or 2
In the second test D; BM weighs 2.2 and the small melon weighs 1.1. the ratio is 2:1 or 2
In the third test E; BM weighs 1.1 and SM weighs 1.1. the ratio is 1:1 or 1

Since we know that BM is larger than SM then we know that the third test E has changed the parameters or reduced the weight of BM.
I hope that clarifies my argument and dispel the side points of the three systems being different. Regardless of the system of measurement the ratio must remain constant.

 

The pressure ratios established by any single method will not change significantly by switching to another method.
The ratio in CUP must be close to the ratio of the same pressures when measured in CIP pressure units or SAAMI pressure units.

If the ratio changes then someone has changed the parameters.

5280 feet is 1 mile, so is 1760 yards or 1609.344 meters The system used to measure it always gives the same result.

 

It is not the unit of CUP that is being questioned, it is the process in which the pressure unit is collected. The process for measuring CUP varies in such a way that it cannot be directly and consistently correlated to PSI.

 

Again, 375Carp, I am not directly translating the CUP pressures to PSI.
The ratio of pressures taken with CUP must be similar to the ratio taken by any other measurement system.

I could use the ratio of 38 Special data taken with CUP and the 357 data taken with CUP and compare that ratio to the ratio of the same two cartridges in PSI. The ratio should be the same (or very similar).

The ratios arrived at with one system have to be the same (or very similar) as any other system unless the pressure difference has changed.
Most of us agree that the performance of the 357 has been reduced. Some want to believe it is the result of more exact pressure measurement. I believe it is because the pressure was purposely reduced and the reason (not backed up by any hard evidence) is that the originator of the cartridge and at least one other (likely 2 others) petitioned a drop in pressures so they wouldn't have to make guns that were strong enough to handle the pressures.

There is some evidence to the weak gun scenario: There is a manufacturer who sells a 357 magnum handgun with instructions in the user guide that tells owners not to use a steady diet of 357 magnum ammunition and that 38 Special +P will extend the life of their gun.
In my opinion that company has made a 38 Special that can handle 357 magnum ammo on an occasional use basis. Other manufacturers do not limit their 357 magnums to frequent use of 38 special loads. They recognize that people buy a 357 to shoot 357 ammo. For those that want to shoot 38 ammo they make 38 Special guns.

 

So why are you beating the dead horse, Paul?

Well, I think I know why. Because you think that measurements in CUP are repeatable.... which they are NOT, to a staggering degree. Hence, comparing one company's CUP data for a cartridge, to the CUP data for another company testing the SAME cartridge, can vary in results on the order of something like 23%- and that was ONE experiment. No guarantee that the experiment conducted again, wouldn't come out worse. It has been documented; go and read.

Go read Nick's thread here, specifically the first and third posts, and get back to us, once you understand this.

https://www.shootersforum.com/balli...allistics-internal-external/92334-differences-pressure-measurement-systems.html

Comparing CUP data from one cartridge, to another, is beyond hopeless. Beyond!

A error of plus or minus more than 10% is BAD. Very, very, very BAD. Not the basis you want to make informed decisions on. Did I mention that it is BAD??????

Sheesh!

 

The 'light' .357s were the result of lobbying by Bill Jordan the head of the Border Patrol. His guys actually carried .357s instead of the PD .38s so common of the time. The S&W, K frame Model 19 was the result.
Light frame guns are beat to pieces faster than heavier, stronger frames. When I was a deputy, 90% of duty guns were M-19s and Pythons. Nobody I ever knew carried an N frame .357 on duty because you don't need weight, you need firepower.

A gun company can limit ammo specified for their guns and deny warrantee service if not obeyed. Shooting 3" ammo in a 2 3/4" gun is a good example.
If you want a lightweight .357, be advise it won't last long. I've already seen a shot-up alloy Lady Smith .357 and I've seen several M37 Airweight Chiefs wrecked with +Ps.

 

Copper crushers are nothing more than pieces of a certain gauge copper wire snipped to a certain length. As we know, copper, like brass, work hardens throughout the drawing process so from where "crusher A" was cut to where "crusher X" was cut there may be a good bit of difference between the "hardness" of the two pieces. There's no real exact way to test the crushers other than to, well, crush them, so the "science" of copper crushers is really just a SWAG.

Just my opinion from reading older reloading manuals.

RJ

 

In 1970 I bought a Ruger Blackhawk 357 magnum , my first and only 357 magnum, and also picked up a new Speer Manual for Reloading Ammunition Number 8 .
I used Speer's data to work up a load . With a 158 grain cast SWC , Unique powder showed a starting load of 7.0 grs. and a max load of 8.0 grs . ... I split the difference ...7.5 grains Unique . 6 shots produced 1 ragged hole group.
I had found my load ! It has worked for 50 years now ....
I don't really care which way you measure it or what you call it ...I'm going to continue loading my "pet" load.
50 years of shooting trumps a bunch of number gibberish .
The proof of the pudding is in the eating ...or in this case the proof of the loading is in the shooting !
Gary

 

I have a yellow box of 158 grain Silver Tip W-W .357 Mag ammo from about 1960. Should I run it through the chrony?

"Pressure" on the bullet can be measured pretty accurately and as long as Newton applies should be a very good indicator of cartridge pressures.

You could contact SAAMI and ask for the previous 'standards'. The latest for CenterFire Rifles is Z199.4 2015.

Abstract--- In the interests of safety and interchangeability, this Standard provides pressure and velocity performance and dimensional characteristics for centerfire rifle sporting ammunition. Included are procedures and equipment for determining these criteria.

 

Let's take this example and simplify it, for those who won't read Nick's post.

Say you have a distance that you think is a mile (5,280 feet), that you need to convert into kilometers. Suppose you hire nine different surveyors to measure it. The 9 different surveyors come up with the following measurements, for the exact "point A to point B" distance that you need:

5,411 feet
4,858 feet
5,993 feet
5,309 feet
4,771 feet
5,498 feet
5,396 feet
5,382 feet
4,902 feet

WHICH one of the nine measurements, are you going to use as the basis for calculating the conversion of miles to kilometers? Remember, they all "measured" the exact same thing!!!!!

That's what CUP gives you. Sorta.... kinda.... in the ballpark.... most likely.... type of measurement. And go to a DIFFERENT cartridge, and get a different set of random numbers. Then compare the first set of random numbers, to the second set of random numbers, and work on the correlation between the two!

Hope this illustrates how absurd it is, comparing CUP to PSI.