What Ken Waters actually said--draw your own conclusions:

quote:

Ken Waters, “Developing Pet Loadsâ€, Sep. 1982 Handloader magazine, p6a ff.

“Controlling pressure is therefore a major concern for handloaders, but to control it, we must first have some means of judging the height of its peak. Ballistics laboratories utilize special pressure barrels and copper or lead crusher gauges—or, alternatively, electronic transducer strain gauges—to measure chamber pressure. Such systems, however, require both costly equipment and skilled technicians, placing them beyond the reach of individual handloaders.

Even if we had a pressure-barrel setup and knew how to use it, that still wouldn’t tell us how much pressure that identical cartridges would develop in the barrel of our favorite sporting rifle or the cylinder of our favorite revolver, they being so entirely different in factors that affect pressure as well as in their abilities to withstand chamber pressures.

I have agreed to explain in detail the system that I’ve been using for some thirty years in developing handloads totaling countless thousands of rounds for a variety of both standard and wildcat cartridges. It has yet to let me down.

Two terms that I use are somewhat different from those in wider use concerning the same concepts—developing rather than working-up loads, since it is frequently necessary to work down from early loads and unsafe to work up; and judging rather than reading pressures since any such method is far too inexact to qualify for any term such as reading that implies a greater precision than is actually the case.

Now of course, no such system of judging pressures can reveal the actual pressure in pounds per square inch or copper units of pressure. It must be understood that this is only a means of determining comparative pressures, with nothing more to be expected of it. With the data provided, the pressures of my handloads can be classified as moderate, normal, near maximum, maximum, or excessive—which is all that is necessary to ensure the safety of the shooter.â€

And I agree with most of it, except that it cannot resolve five categories, as Ken thought it could, and it is far short of ensuring the safety of the shooter. The cost of the equipment is now within reach of anyone who really wants it, and the skill required is within even Hot Core's slender grasp.

Hot Core, you may recall that we wanted you to participate in the experiment that generated the data in the graph. We agreed to have Dutch hold the data, so that I could not see who generated which data set when I analyzed it. You may also remember, as many of us do, that you absolutely ran from the prospect of a controlled experiment, saying that you had no need to check a method that you knew worked. Despite numerous requests, you declined to participate. That certainly shows a lot of confidence, doesn't it? And gives you great standing to criticize, too.

Now you baldly lie, and say that I have fabricated the data to make you look bad. Such a lie is sooo easily detected: How would you have any way of knowing such a thing? And why in the world would I do that, when the results are so easily replicated? You attach too much importance to yourself. I don't actually care what others think of you. That's your problem to solve, if you can.

You have no facts, no figures, and no physics. You present no evidence, you lie, and you sneer at the people that took the time to actually generate real data, because you don't like the result.

Time to grow up, Hot Core.

quote:

Originally posted by Joe Cullison:

A very wise man once told me that "if you have a safe load that performs the way that you want it to, who cares exactly what the pressure is?" He also said if you get the kind of accuracy you want without doing all of the little brass prep tricks, runout measurements, neck turning, then why bother? Just load and shoot. Sometimes it's just not worth sweating the small stuff. If it is not working for you then don't do it.

Just so. And I would add, who needs to know the velosity precisely either. Just check drop at longer ranges.
John L.

quote:

2. Let's say the Factory cartridge above is a 308Win with an Average SAAMI Pressure of 52,000cup as listed in most any Manual

Hot Core this is where we differ.

The factory pressure is NOT a average at 52,000 CUP but does not EXCEDE the SAAMI max average of 52,000 CUP, a big difference. Especially when you realize the average has a high and low figure that you know nothing about.
Does the factory except a 5% pressure spread as exceptable?
How about 10%?
If the load averages 52,000 cup does it swing from 49500-54500 cup?
Which pressure did the round you fired produce in the factories barrel?
How much pressure does this ammo produce in your rifle?
I understand your line of thinking that pressure must be the same or less but, brass work hardens, especially with larger chambers and min tolerance dies, and spring back changes slightly. Are you sure yours is still recovering at the same rate as with the first fireing? Did you measure the same spot on the case?
I still feel PRE only tells me I`m in the ball park of factory pressure due to "similar" brass expansion. I neither know what the cartridge produced as far as pressure in a factory pressure barrel nor do I know what it gave in mine, simply that it can be concidered comparable to what the factory conciders safe because of the brass`s reaction. Remember this is a cartridge case, not a calibrated "crusher" pellet, nor do we have a tare table for it.

BTW, I do have a pressure trace. I haven`t used it much yet, and I am still learning what it`s telling me exactly. I also have used PRE for ~15 or so years, and still measure it from habit if for no other reason. Brass is the weak link in our ammo and it diesn`t hurt to keep a eye on how it`s reacting. Both are tools and both have a useful place along with velocity. I just don`t give PRE as much weight as you do.

Joe Cullison,
I recieved my new copy of Handloader magazine today and found there is a artical on pressure and Velocity that mentions PRE, CHE, strain systems ect by John Barsness. (Aug 2005, issue #236) I found there is a lot of what has been argued here mentioned in the artical with some interesting findings by the author and Charlie Sisk if your interested.

quote:

Originally posted by Joe Cullison:
Tiny, the powders used in the manual are chosen for being appropriate in burn rate and case fill per cartridge. There must be a minimum case fill and they try to use powders that will get the most velocity without exceeding the SAAMI max. They also look at what everyone else has tested and see if any new powders have come out that might be appropriate.
They do test other powders that do not get published, they will neither discuss nor disclose this information.
If you have a question about a specific powder, bullet, cartridge combination you can call Mike Harris at Nosler technical services. He may be able to guide you. He is one of the people I go to with questions. Joe

Thanks.

quote:

Originally posted by Ol` Joe:

quote:

2. Let's say the Factory cartridge above is a 308Win with an Average SAAMI Pressure of 52,000cup as listed in most any Manual

Hot Core this is where we differ.

The factory pressure is NOT a average at 52,000 CUP but does not EXCEDE the SAAMI max average of 52,000 CUP, a big difference. Especially when you realize the average has a high and low figure that you know nothing about.

Hey Ol' Joe, You are selectively misreading what was posted. The statement above (#2) simply says I'm using the 308Win as an example. And that the SAAMI Average Pressure for that cartridge is 52,000cup.

But you must have overlooked #1:

quote:

Originally posted by Hot Core:
1. Since you mentioned it is a "Factory" case(I believe you meant cartridge), I would guess you will agree the Factory cartridge is intentionally manufactured so it is, slightly less than or meets the Average SAAMI Pressure Specification? ...

quote:

Does the factory except a 5% pressure spread as exceptable? How about 10%? If the load averages 52,000 cup does it swing from 49500-54500 cup? Which pressure did the round you fired produce in the factories barrel? How much pressure does this ammo produce in your rifle?

Knowing the actual Pressure has no advantage with PRE because it is simply a "Comparative" measurement against whatever the Average Pressure happens to be. You should Averaging the PRE for the box to reduce the normal manufacturing variability - smoothing out the Highs and Lows(which you mention) to a useful Average.

However, if a person is that concerned about what the actual Pressure is in Factory ammo, then (following your logic) they should never shoot any of it. And as we know, Billions of rounds of Factory made ammo is fired around the world every year with extremely rare recalls due to over Pressure.

The only place that knowing what the actual Pressure of a cartridge is of worth is if you are actually attempting to Calibrate a totally worthless non-calibrated HSGS and turn it into a useful SGS. As far as I know, Hornady is the only company willing to provide the Average Pressure Range of it's ammunition when it is requested by Lot #. Buying the actual Certified SAAMI ammo is way to expensive for the average reloader.

quote:

I understand your line of thinking that pressure must be the same or less but, brass work hardens, especially with larger chambers and min tolerance dies, and spring back changes slightly. Are you sure yours is still recovering at the same rate as with the first fireing?

Over the years I've found CHE is good for the Second through 6-9 firings depending on the actual strength of the Loads being tested. If they are all wide-open, then the case is much less reliable as the count increases - so we agree.

I've also found PRE is good for the First through 6-9 firings, again depending on the actual strength of the Loads being tested. If they are all wide-open, then the case is much less reliable as the count increases - so we agree again.

quote:

Did you measure the same spot on the case?

For CHE absolutely.

For PRE, you will get the best possible data if you rotate the case until you locate the "widest diameter". This is done with care so the actual reading is not improperly skewed by forcing the Wide Point through the anvils of the 0.0001" capable Micrometers.

As an Example, let's say you rotating the case between the anvils of the Micrometer on the Pressure Ring, and at 0.4xx5" the case turns freely. But when the reading is 0.4xx4" the case will "hang" between the anvils. That is the most accurate PRE data you can get. And is much more accurate than trying to Average the PRE readings around a case.

The "Wide Diameter" is normally in one spot on a fired case. This is because the Case "Wall" thickness is rarely perfectly uniform, so it stretches more, where it is thinner. And some Chambers are slightly out of round too, which can influence where the "Wide Diameter" is located on the case.

quote:

I still feel PRE only tells me I`m in the ball park of factory pressure due to "similar" brass expansion. I neither know what the cartridge produced as far as pressure in a factory pressure barrel nor do I know what it gave in mine, simply that it can be concidered comparable to what the factory conciders safe because of the brass`s reaction. Remember this is a cartridge case, not a calibrated "crusher" pellet, nor do we have a tare table for it.

Completely AGREE!

quote:

BTW, I do have a pressure trace. I haven`t used it much yet, and I am still learning what it`s telling me exactly.

How did you "Calibrate" it to a known Standard?

quote:

I also have used PRE for ~15 or so years, and still measure it from habit if for no other reason. Brass is the weak link in our ammo and it diesn`t hurt to keep a eye on how it`s reacting. Both are tools and both have a useful place along with velocity. I just don`t give PRE as much weight as you do.

I've been using it a bit more than 3-times that long and haven't found anything better yet.

Back when the HSGS devices initially came out, I thought they would be the thing to provide better and more concise Pressure data for the average reloader. Then I got to looking into them and realized their inherent weaknesses make them fairly impracticle and pretty much worthless for anyone outside a Lab environment. You can't get accurate Chamber Wall thickness readings with normal measuring devices people will have in their homes, and Calibration Ammo(Certified to SAAMI) was way too expensive prior to Hornady providing the info.

Plus you have to stick that Strain Gauge to the barrel which looks real cute! Or hide it beneath the stock and totally screw-up the bedding. Just not options for "my" rifles.

So, as I re-read the above, it looks like to me we agree about the vast majority.

BTW, Ol' Joe, How many stresses can you place on a Strain Gauge before it is useless?
---

For those new members of the Board, I did forget to mention one of denton's "qualities" is that anytime he disagrees with a person, he calls them a Lier or resorts to some form of Sophmoric name calling. Everything I said in the thread can be found by searching the Board for past discussions we have had. I have no reason to Lie since it is all right there for anyone to see.

But the HUGE KILLER is you can duplicate the things I mention for yourself and see that what I'm posting is simply based on experience.
---

Just went back and noticed where denton actually "believes" he knows more about Ballistics than Mr. Ken Waters.

When someone speaks of "Double Blind Experiments", and Placibo effects applied to CHE they lose a whole lot of credibility.
These are tests to see if there is a true correlation between measurements. Anybody out there really think that CHE is not related somehow to pressure?. It does show that the case is begining to yield, and you should take a minute to reflect on what you are doing.
Good luck!

quote:

How did you "Calibrate" it to a known Standard?

Already answered, many times, with references to the appropriate supporting NIST documents.

quote:

BTW, Ol' Joe, How many stresses can you place on a Strain Gauge before it is useless?

According to the manufacturer, many millions.

quote:

Or hide it beneath the stock and totally screw-up the bedding.

Ridiculous. Another unsupported assertion.

quote:

And that the SAAMI Average Pressure for that cartridge is 52,000cup.

That's the maximum allowed. Many factory loads are below maximum.

quote:

Knowing the actual Pressure has no advantage with PRE because it is simply a "Comparative" measurement

This from the person who swore in post after post that PRE is calibrated?

quote:

The entire thing got started because denton thought he could "prove" CHE & PRE did not work at all.

Bald faced lie. As many remember, my original position was that I didn't know whether PRE and CHE worked, and that we needed a test to find out. That's the test Hot Core ran away from. The test shows that they work poorly, but that if you do enough averaging, you can get a meaningful relative comparison out of them. That is what I have represented here, after the test.

quote:

his actual knowledge using them is tainted by his desire for them to work perfectly

Another easily detected lie. Now you claim to read my mind?

Actually, my experiments measured the error inherent in the strain gage system, and published it for all to see.

quote:

Just saw another thread where he posted a load as 54.4kPSI, with no Range given for the Pressure. As if his non-calibrated HSGS is accurate to PSI in hundredths. Pitiful!

Again your incompetence and deceit are showing. I have clearly and frequently stated the random error inherent in the strain gage system, an error SD of about 670 PSI. Rounding to the nearest thousand would add approximately another 330 PSI of error, and is bad practice.

quote:

comparing it to the Factory Cartridge Average PRE, you know your Pressure is at or below 52,000cup.

This five digit result, from the man who complained so bitterly because I expressed my result to three digits? And with no error range on it?? Rank hypocrisy.

quote:

I've been using it a bit more than 3-times that long and haven't found anything better yet.

What else have you tried, and what tests have you performed to evaluate it? How would you know if it didn't work?

quote:

I did forget to mention one of denton's "qualities" is that anytime he disagrees with a person, he calls them a Lier or resorts to some form of Sophmoric name calling.

Nice technique--accuse the other person of what you blatantly do. Time to grow up, Hot Core.

quote:

But the HUGE KILLER is you can duplicate the things I mention for yourself and see that what I'm posting is simply based on experience.

So present your data and test results. Let's see 'em.

quote:

I'm an EE, myself.

No you're not.

quote:

Anybody out there really think that CHE is not related somehow to pressure?

The graph that I posted clearly shows that it is. As pressure increases, so do PRE and CHE They also have a very large helping of random error mixed in, which is a problem that can be solved with sufficient averaging. The question is not whether it works. The question is whether it works well enough to be very useful.

Hello JAL,

Apparently 2 full grains of IMR4198 is a lot in a small case that only has about a 24-25gr. capacity. I save my old manuals, but now keep them on a back shelf out of harms way. I have no desire to ascend to heaven on a pillar of flame. Best wishes.

Cal - Montreal

quote:

A three shot string is useful. I use them all the time for accuracy testing...then I let the barrel cool and shoot another...then I let the barrel cool and shoot another. Then I can see what the average group size is for three (three shot) groups. Hmmmm that adds up to 9 well almost ten shots. I certainly trust that over one group, so wouldn't that apply back to any other variable being tested. I'm sure our statasticians would agree that it does.

quote:

O.K., I'm hooked.
I use that exact sequence while working up loads over the chronograph. I also depend heavily on PRE and factory ammo as a control measure. It is affordable and easy to learn, whereas a personal ballistic laboratory and the skill necessary to use it isn't. I never use CHE as the way I see it, if the case head moves, a solid object with substantial mass as compared to the case wall, you're already in jeopardy.
Also, when reaching for the maximum and beyond in calibres like the venerable -06, I do so in 1/2 grain increments over the chronograph. At some place in the process, one will reach a point of diminishing returns in velocity vs. powder burned. It is at this point where velocity increses in progressively smaller increments and pressures rise with no real benefit to the shooter.
In a nutshell, this has kept me safe for many years.

Gentlemen, FYI I use everyting as a "guide" including the excellent Quick Load program which shows that actual pressures for that given load but shows three levels of maximum pressures.
In the BR discipline, chambers and necks are cut very tight so there is little room for expansion so a BR laod that has no excessive cratering or expansion would be dangerous dangerous in a factory chamber. Overbore

Would somebody explain something to me regarding the metallurgy and brass? I know steel has yield and failure limits, and the properties would be amenable to the CHE/PRE methodology I guess. Question is, does brass behave in the same manner, and how is it affected by different alloy mixtures? I assume since there have been caveats mentioned about using factory ammo/brass as a comparitive baseline for pressure it is judged as a pressure reference. In a recent article by Dave Scoville he indicated his method was to fire factory ammo, do the measurements etc, and then work his loads up with those specific cases. Makes some sense to me, but I am clueless about the properties of brass. And curious too. Somebody want to clue me in?

Dan, your question cuts to the heart of the problem.

Brass varies. Not just from manufacturer to manufacturer, but also from batch to batch. Annealing procedures, temps, and at which stage during the drawing process the annealing takes place.

When I tossed out my WSSM example, I did so for a reason. It is by far the thickest brass I have ever seen. Based on velocity readings and Quickload simulations, I would say that the spring back in that brass is such that you must run pressures over 55,000 PSI to fully obturate that brass. You can reload the stuff without resizing (even in a roomy chamber with .01 neck clearance) if you keep pressure below about 55,000 PSI.

Something like 30/30 brass is far thinner, and obturates far quicker.

So, if PRE were to be used, the user has to calibrate to each lot of brass, for each cartridge, for each rifle. That limits it's usefulness. To "none", in my case. JMO, Dutch.

quote:

Originally posted by Cal Sibley:
Hello JAL,

Apparently 2 full grains of IMR4198 is a lot in a small case that only has about a 24-25gr. capacity.

Cal - Montreal

G'day Cal, and others.
What I was trying to ask you i guess was, no matter how old the manuals are, should a powder manufacturer sell a powder under the same name, that requires 2 gr less in a small case??
EG. Call it IMR 4198 + + or 4200 or something.
John L>

Well, I sorta thought it might play in the discussion, and I'm very aware of the differences in wall thicknesses. Started my rifle reloading with the Hornet.

If you're saying brass does exhibit similar characteristics to steel vis-a-vis yield/failure limits I then infer that if one exceeds yield limits for a particular alloy you will see measurable dimension change, both for PRE and CHE. As Joe inferred/stated above however, with lower pressure loads you will not surpass this threshold and no measurable change occurs. Is there any source of info that defines these figures for specific brass alloys? And how does it play as the brass hardens with work cycles?

Seems like a lot of variables can be induced here, so at what point do you say this brass is no longer useful for the evaluation? 2-3-4-5 firings? Or given a generous chamber and typical dies, does the work hardening obviate any usefulness at all?

Wouldn't it be nice if SAAMI standardized the alloy for the industry?

Dan,


There certianly can be mettalurgical variations expected from brass. Different sources of metals (mines around the globe) will contain different levels of purity and impurities, and then there are a number of different refining procceses not to mention variations in QC from one refinery to another. Most any refining process will do a lot to "clean up" the metal if you will, but even todays very best process can only do so much to fix it. Remember the Ackley action tests and the high carbon content found in Jap steel that made them virtually indestructible? The non-ferrous metals are also subject to such variances.

What does that mean to us? IMHO I dont think it is very significant but it could well be the one of the biggest culprits for the large variations seen in manuals. The brass (and primers) are the weakest link(s) in any given weapon, so when you see the traditional signs, be it with brass made from second rate metal or from the best in the world, it is still the case saying uncle and it has reached its limits. The difference is obviously that the better brass will tolerate higher pressures before reaching its limits. How much difference one might find would depend greatly on the specific metals.

I expect that if someone were to do a little reasearch on purities and characteristics of brass from specific reigons, they may well be able to pinpoint who in fact does make the best brass on the market.

Dan, Dutch cut to the core of the problem. Even the exact same alloy of brass will have different hardness, if the forming and annealing processes are not the same. Cases are designed to hold the powder, primer, and bullets, without much concession to making pressure measurements.

Copper is easier to make uniform. As I understand it, the whole PRE/CHE thing was tried back in the days of Custer, when cases were copper, and was abandoned in favor of the crusher method, because even with copper cases, the results were not sufficiently repeatable.

There are also other limiting factors. I did the test-retest thing on one case, making sure that I measured the exact same point on one case, over and over again. Son of a gun, the Effective Resolution came out .00005", just like they advertise. However, when you rotate the brass, per Ken Waters, to find the high spot, Effective Resolution drops to .00017". There are often multiple high spots, that are very hard to distinguish by feel.

The amount of pressure needed to make a pressure ring is large, and the dimension changes are small. That .00017" Effective Resolution pretty much kills your chances of detecting small differences in pressure.

Dan, the way I read Joe's comments is that Nosler uses the brass a total of once?

JAL, Lot to Lot has always varried +/-10% and often as much as 1 heat range. Remember that line in your manual "when changing any component, reduce 10% and work up again"?

"For PRE, you will get the best possible data if you rotate the case until you locate the "widest diameter". This is done with care so the actual reading is not improperly skewed by forcing the Wide Point through the anvils of the 0.0001" capable Micrometers."

"Knowing the actual Pressure has no advantage with PRE because it is simply a "Comparative" measurement against whatever the Average Pressure happens to be. You should Averaging the PRE for the box to reduce the normal manufacturing variability - smoothing out the Highs and Lows(which you mention) to a useful Average."
________________________________________________

-Hot Core,

I do average the high measurements. I measure with a Starret mic with a claimed accuracy of 0.0001" and a claimed resoultion of 0.00005" at 8-9 points around the case head. The PRE changes quite a bit (as you note) in just a minute or so of arc so multiple points have to be checked to insure the max has been found. I avg the high points (normally off 10 rds) and record. I also note the max expantion measured in a string of measurements.

________________________________________________
"I've also found PRE is good for the First through 6-9 firings, again depending on the actual strength of the Loads being tested. If they are all wide-open, then the case is much less reliable as the count increases - so we agree again."

-I agree useful case life is limited, but I`m still not sure how much. I believe Waters in his articals on useing PRE claimed he only used case up to three loadings. I may be wrong, I don`t have a artical with me to dbl check but, thats been stuck in my memory for years as his figure. He also stated the first fireing with milder loads would be suspect and didn`t always use PRE on NEW CASES unless they were getting up in pressure.

This is similar to your question as to strain gage life. My belief,your`s, Dentons, PT`s, all will vary. I use a "varification load" to check to insure the gage is still giveing similar response to the last time I used it. As it now stands, when the varifaction load shows pressures different from the previous ones I most surely will suspect the gage has reached its end and remove/replace.
________________________________________________

"How did you "Calibrate" it to a known Standard?"

-I haven`t.
I did fire factory ammo through the rifle(s) and will "COMPARE" the readings I get for my loads to the pressure reading from the factory load. I realize this dosen`t tell me if the pressures I read are true or not but I do know to a couple hundred PSI where they stand inre to factory pressure.

BTW..... I fired two factory loads in 270 Win in my gaged M70, one Remmington 140gr load and one Winchester 130gr load. Both had the same PRE - 0.4689" max expansion, but there was 5.4K differance in max pressures according to the pressure trace.
This doesn`t tell me much except it`s possible Rem and Win brass reacts at a different rate (something we already know) or just because the SAAMI max pressure for a load is known doesn`t mean the factories are loading it for one reason or another.
Both gave their respective factory listed velocities with in 20/30 FPS from my 25.5" bbl.
________________________________________________

"Then I got to looking into them and realized their inherent weaknesses make them fairly impracticle and pretty much worthless for anyone outside a Lab environment."
________________________________________________

-Mmmmmm. Two loads with top velocity. The PRE of both suggest the brass is at its same yeild point and with in factory parameters. Accuracy is with in reason for both. But one is over 5K lower in pressure.
Wonder which is easier on the barrel throat, bolt lugs, ect...........?

-Yep, worthless outside a lab..............

Hot Core, I still agree on a lot of what you say. PRE has a place and did / has kept me safe for years, I just can`t get myself to believe it`s the best thing since pockets on pants.
IMO there is better..................

quote:

A very wise man once told me that "if you have a safe load that performs the way that you want it to, who cares exactly what the pressure is?"

EXACTLY my thoughts on this subject!

quote:

Originally posted by hawkins:
When someone speaks of "Double Blind Experiments", and Placibo effects applied to CHE they lose a whole lot of credibility.
These are tests to see if there is a true correlation between measurements. Anybody out there really think that CHE is not related somehow to pressure?. It does show that the case is begining to yield, and you should take a minute to reflect on what you are doing.
Good luck

Dan, your question cuts to the heart of the problem.

Brass varies. Not just from manufacturer to manufacturer, but also from batch to batch. Annealing procedures, temps, and at which stage during the drawing process the annealing takes place.

When I tossed out my WSSM example, I did so for a reason. It is by far the thickest brass I have ever seen. Based on velocity readings and Quickload simulations, I would say that the spring back in that brass is such that you must run pressures over 55,000 PSI to fully obturate that brass. You can reload the stuff without resizing (even in a roomy chamber with .01 neck clearance) if you keep pressure below about 55,000 PSI.

Something like 30/30 brass is far thinner, and obturates far quicker.

So, if PRE were to be used, the user has to calibrate to each lot of brass, for each cartridge, for each rifle. That limits it's usefulness. To "none", in my case. JMO, Dutch.

You can always tell a Dutchman, but you can't tell him much !

Case head expansion is of course related to pressure. However, not all brass cases are the same. Years ago, it was possible to get BETTER PERFORMANCE from the .300 Winchester using Winchester cases than from the .300 Weatherby using Weatherby cases made by Norma. In those days, Norma brass was so much softer that primer pockets expanded before .300 Win. performance levels were reached. However, if one made his .300 Weatherby brass from Winchester .300 Win. H&H cases, the .300 Weatherby was capable of beating the .300 Win. substantially.

quote:

Originally posted by Ol` Joe:
...Hot Core, I still agree on a lot of what you say. PRE has a place and did / has kept me safe for years, I just can`t get myself to believe it`s the best thing since pockets on pants. IMO there is better...

Hey Ol' Joe, I figured we could agree on most of it.

What do you consider "is better"?

quote:

Originally posted by Hot Core:
Then I got to looking into them and realized their inherent weaknesses make them fairly impracticle and pretty much worthless for anyone outside a Lab environment. You can't get accurate Chamber Wall thickness readings with normal measuring devices people will have in their homes,

HC, you would (apparently) be amazed at how many people can do this in their home. This is NOT high tech measurement, and does NOT require NIST tracable, certified measuring instruments, just repeatable ones and those are not hard to come by. I'm happy to loan out mine to anyone who wants to meet me at the range for an afternoon's shooting session (at my local range of course, unless you buy me plane tickets!) One doesn't have to own them, just have access for a bit of time, or make a visit to your gunsmith.

Using a certified micrometer makes the strain gauge system truely calibrated. You need to understand the difference between a DIRECT calibration, i.e. comparision to a known standard using the same measurement units (pounds to pounds, meters to meters, etc.) and an INDIRECT calibration, i.e. meters measured in wavelengths of light in a vacuum (yes, that is the current Standard at NIST), time in vibrations of cesium atoms, or PSI measured in lb mass via a deadweight tester. IIRC, the mass standard was the ONLY direct standard left used by the NIST! All others are indirect!

The data from strain gauge systems is good enough. Worst case is to use factory ammo as a 'reference' (as opposed to cal.) JUST LIKE CHE/PRE! Improve your sensitivity and resolution by an order of magnitude for a couple hundred bucks. Sounds like a decent return on investment for many!

quote:

IIRC, the mass standard was the ONLY direct standard left used by the NIST! All others are indirect!

Absolutely correct.

quote:

You can't get accurate Chamber Wall thickness readings with normal measuring devices people will have in their homes

Within .001-2" is abundantly adequate, and easily possible. It is much easier than measuring brass to within .0001".

quote:

Originally posted by Tailgunner:
Remember that line in your manual "when changing any component, reduce 10% and work up again"?

Heck, I didn't consider one tin of H4198 to another was changing components.
John L.

quote:

Originally posted by Ol` Joe:
...Hot Core, I still agree on a lot of what you say. PRE has a place and did / has kept me safe for years, I just can`t get myself to believe it`s the best thing since pockets on pants. IMO there is better...

Hey Ol' Joe, I figured we could agree on most of it.

What do you consider "is better"?

quote:

Hey Ol' Joe, I figured we could agree on most of it.

What do you consider "is better"?

Hot Core, PRE gives me a idea if my brass is reacting less, the same, or more then, to my pressures then factory brass reacts to factory pressure. I figure the amount factory brass deforms is within safe parameters and as long as mine doesn`t excede it I`m hopefully also operating at safe/sane levels. This hasn`t told me a thing as to what pressure levels I`m at though.

I haven`t played much, as I stated, with the trace system yet. So far though it has shown me a differance in pressure between 270 Win factory loads from two different manufactures (one with 130 gr bullets and the other a 140 gr load)that gave the SAME AVERAGE PRE when measured, 0.4688", but had almost 5K average differance in pressure according to the trace and 4K in max recorded pressure.

I`ve also tested a load I`ve used for quite a while in this rifle with the same brand, but not lot, case as the factory 130 gr load and useing a comparable 130gr bullet. The factory load gave 3159 fps compared to my reloads 3041 fps and PRE of 0.4694" average 0.0006" more expansion, and the load is 3 gr under book max!! The Pressure Trace showed almost 6K less pressure in favor of my handload.

I`ve always been told the 270 was loaded to the max as it comes from the factory but in this case one was definatly at a lower pressure range and my handload was within ~100 fps at much lower levels. Both factory loads gave expected velocities in my 26" BBL as did my handload.

Now this tells me it`s possible I`ve loads with similar PRE that operate at notable variation in pressure. Both could be safe but one is going to be easier on my rifle and if accuracy is exceptable in both the lighter pressure load is by far prefered...........I think you see where this is leading in reguards to your question.

quote:

Originally posted by Ol` Joe:
...Now this tells me it`s possible I`ve loads with similar PRE that operate at notable variation in pressure. Both could be safe but one is going to be easier on my rifle and if accuracy is exceptable in both the lighter pressure load is by far prefered...........I think you see where this is leading in reguards to your question.

Hey Ol' Joe, If that "Trace HSGS" is that goofed up, maybe they will give you a refund and take that fiasco back.

I see and understand your conflict.

Best of luck to you.

quote:

I see and understand your conflict.

How would you see that? You have exactly zero experience with the product.

DD,

quote:

In a recent article by Dave Scoville he indicated his method was to fire factory ammo, do the measurements etc, and then work his loads up with those specific cases.

Yet, in Rifle #177 he says,
"In short, once a case is fired in a chamber, it isn't suitable for pressure testing in a pressure barrel, and it may not give accurate readings with a strain gauge either. So even miking cases may not be all that accurate, which is why I think most load data for wildcats that is based on cases that have been used repeatedly for developing loads is off the mark--sometimes by a wide margin. For ballistic labs to achieve accurate and repeatable results, they restrict the use of cases to one firing and toss it. Otherwise, there is no way to predict how much effect repeated firing may have on case head expansion, on transducers, or strain gauges."

Scovill makes up his own rules as he goes along.

Tailgunner and onefunzr2 are correct.
Nosler uses each piece of brass only once when working up loads for the book (pressure testing).

All loads fired there are recorded with the pressure testing system and the records are kept on the computer. Only loads being tested for the book use virgin cases and are measured for PRE and checked against Reference ammo.
Joe

quote:

Originally posted by Joe Cullison:
Tailgunner and onefunzr2 are correct.
Nosler uses each piece of brass only once when working up loads for the book (pressure testing).

All loads fired there are recorded with the pressure testing system and the records are kept on the computer. Only loads being tested for the book use virgin cases and are measured for PRE and checked against Reference ammo.
Joe

I assume that this is because a case changes hardness to some degree every time it has a load fired in it-it gets harder each time, so the first firing is the only meaningful one......

quote:

Tailgunner and onefunzr2 are correct.
Nosler uses each piece of brass only once when working up loads for the book (pressure testing).

Looks like even the experts can`t agree on this one.
From the Speer #13 pg 53......

"New cases can give deceptive expansion readings. The first firing of any case will usually cause more deflection of the web then subsequent firings. At Speer, we start with once-fired brass so the initial deflection is accomplished before testing begins."

Speer uses CHE not PRE in their tests, and add that they stop useing brass after 3 firings due to work hardening concerns.

quote:

All loads fired there are recorded with the pressure testing system and the records are kept on the computer. Only loads being tested for the book use virgin cases and are measured for PRE and checked against Reference ammo.

Joe,
This sounds like what I`ve been trying to do with my loads. I have been checking the pressure with the trace system and brass PRE to see that both fall within the factory standard - for no better term - that I`ve found when measuring factory ammo.

I figure a couple checks and balances never hurt. Toss in velocity expectations from my manual and I`m likely as anal as one can get.
Don`t know how I managed to put together a safe load these last 40 yrs..........

Hey Joe Cullison, Back on page 1 of this thread I'd asked:

quote:

Just wondering "why" you all never mentioned using PRE in the Manuals? Or, maybe I just missed it.

Well, I had missed it or forgot it was there. Back in Nosler #3 on pages 35 & 36 it describes the method you all use.

Had a buddy email me and tell me to pop open my book and look right there. Sure enough, there it is.

Hot Core, I'll have to go back and read that. Thanks for the info. If only I could remember 1/10th of the stuff I have read.
Joe

Mr. Cullison,
It is indeed a pleasure to have someone like yourself that has a gentlemanly approach to presenting himself on a forum. Sometimes I really get upset at the way people act and talk when the othe person is not in the same room with them. Now-a-days people have forgoten how to act in a respectabel manner when conversing with others.

Again my thats and I hope to bother you with questions in the future.

You mean you haven't been in a room when an all out brawl started from a little sideways glance?
JL :-)

GCA, Quik Load is an excellent program. More data than a lot of folks can understand, I think.

I have been at it for about 25 years and I have a strong engineering background including calculations for pressure, and the last manuals I bought were the Lyman #11 and the Lyman #46 before that. I do have every powder manufacturers load guide that I can get my hands on that have come along since.

In the case of handloading handgun cartridges in particular, I have seen SAAMI unnecessarily reduce the pressure of the 9 X 19mm, mostly because it's not an American cartridge design,(so they could use a marketing scheme of +P that doesn't exceed the original pressure spec) even though it has the strongest casehead of any autoloading cartridge except off-shoots like the 9 X 21 and the 9 X 23. Then they turn around and allow a 40,000 PSI Max. for the .357 SIG whose parent cartridge is the .40 S&W that has had more Ka-Booms than any cartridge in recent history. Now SAAMI has gotten wise and put the magnum revolver rounds back to pressures that are closer to their original pressure specs @ 40,000 CUP. Some powder companies were ignoring them it seems, and they were members of SAAMI!

Do any of you guys know the difference between C.U.P., SAAMI PSI, and C.I.P. PSI, along with the system they all use, but won't tell you about?

quote:

I have seen SAAMI unnecessarily reduce the pressure of the 9 X 19mm, mostly because it's not an American cartridge design

KLN357, I don`t know that it is just an SAAMI thing. The VihtaVuori #3 shows that the 9x19 (Luger) cartridge went from 39200 psi (270 MPa) to 34075 psi PIEZO (235MPa) CIP. The older guns out there may have something to do with it but the note the pressure is now measured with PIEZO and not estimated from a copper chusher tarage table, as they used to, leads me to trust CIP also found the old limit was a bit high. Remember too that SAAMI and CIP measure at different points in the barrel when setting their pressure limit. SAAMI measures at a point in the center of the case and CIP measers a bit ahead of the case mouth. This alone will cause some of the pressure differences you see published.
The case head on the 40 S&W may be thick and strong but it still is the weak point in the system. The chamber design has some to do with the problem with the S&W round, in Glock pistols anyway, as they have a deep feed ramp that leaves a large part of the case head unsupported. ( the famous "glock" bulge')This aids in feeding and helps make the pistol more reliable but, the pistols are known for haveing case splits caused by this feature. Not just 40S&W but other cartridges also have failed in these guns, especially as cases are used over and over in reloads. I don`t think the 357 SIG has any handguns out there with similar chambers.

quote:

Do any of you guys know the difference between C.U.P., SAAMI PSI, and C.I.P. PSI, along with the system they all use, but won't tell you about?

For a bit of back ground on pressure systems used try the VV manual it has some info. Also the A-Square book "Any Shot You Want" has a lot on pressure along with a lot of data on diffferences they found when changing components or lot # with the same components, very interesting stuff IMO.

Ol' Joe, thanks for the response and the question about CIP and such was rhetorical. You are correct about the different locations where pressure is measured in CIP and our Piezoelectric system. +P 9mm spec of 38,500 is very close to the original pressure spec of 35,700 CUP, within a 100 PSI or so anyway.

I haven't seen the VV #3, but I have the #1,2,4,6 and 7, as well as the latest one. I use the #2 most often because the 36,300 limit for 9mm in CIP PSI, is the closest to 35,700 CUP that I started loading with in 9mm long before SAAMI changed it. Appropriate OALs must be adhered to and with 124 gr. Rem JHPs I use 1.142".

The system that is universal is pressure tested in BARS and here the max. for 9mm is 2600 and both American and European powder companies use it and if they provided us uniform data in BARS, personally, I think we would all be better off. They will tell you that they underate their data because guys out there take it for granted that load data is underpowered. Well, they're pouring gasoline on the fire in my oppinion. Anyway, unless the chemistry of a powder has been changed, I go with the older data unless it is a new powder, like Ramshot True Blue that the UPS man should be dropping off anytime now. Of course, powders can change by lot, so I ordered 4lbs. that ought to last me for awhile, and the number of cartridges this powder is supposed to load exceptionally, really has me excited. Many competition shooters have replaced 3N37 with it and that's a pretty good endorsement since I have been loading high pressure cartridges with 3N37 for about 10 years now. I am looking for great things with True Blue and in the .45 ACP, which 3N37 is not great for, it takes on the characteristics of a faster burn rate, somewhere between U/U and HS-6. I will go into this further after some testing!