Ackley had a copper crusher setup. He did quite a few experiments with it.

quote:

"First Hand Pressure Indications" directly from the case rather than "Second Hand information from a Strain Gauge"

This really got me chuckling...

Not that I am agreeing with either as a 'first hand indication', but there is exactly the same number of degrees of seperation in measuring brass with a micrometer as measuring the barrel with a strain gauge...ONE! The rest is all in translating the information into a format we humans can read. I trust the steel of my barrel to react the same each time it is subjected to X psi too...not something that can be said for cartridge brass!

How many times do Denton and HotCore have to pound out the same arguments? I know, rhetorical question...For less than $500 I can have BOTH and decide for myself.

Come on HC, if you say PRE is good enough to be 'the best', it is good enough to validate (as opposed to calibrate) a strain gauge system...or does that circular logic not register??? It isn't, but that point has gone nowhere in the past, now has it?

For those wondering what RSI pressure trace is, look at:

RSI pressure trace web site

ireload2, the 222 case is a smaller diameter case and therefore, given the same internal pressure, there will be less bolt thrust and less chamber wall tension created when compared to the larger diameter cases - do the math (force = pressure x area). There is less area inside those smaller diameter cases.

I saw this on another forun and thought those posting here might be interested. I have a SAKO, but replaced the barrel years ago with a Hart Match-grade Stainless Steel barrel (280 AI).

"alyeska338 - Moderator
Joined: Jan 2002 - Location: Alaska

A limited number of Sako 75's (I believe) are being recalled due to poor barrel metallurgy. If you have a Sako 75 or Finnlite, give them a call to see if your rifle's serial number matches their recall list. 1-800-503-8869.

There's been a few pictures floating around on other forums about showing total destruction of the rifles. Shooters suffered injuries and I, personally, would not shoot a Sako if I owned one before finding out if it was on the recall list or not."

quote:

Originally posted by CDH:
but there is exactly the same number of degrees of seperation in measuring brass with a micrometer as measuring the barrel with a strain gauge...ONE! ...

Hey AIU, This is some of the "foolishness" I mentioned before. But, if infact CDH is talking about a Strain Gauge on a non-cartridge, Black Powder Muzzle Loader, I suppose the above would be correct.

Unfortunately, most folks don't realize with a Cartridge style firearm, you simply get Second Hand information by gluing a Strain Gauge on the chamber. But, since they usually don't bother with Calibrating to a Known Standard, it doesn't really matter anyhow, since all their "data(?)" is worthless.

quote:

Originally posted by Ackley Improved User:
HC, please remember that PO Ackley studied pressure effects in both 30-06 type cases and belted-magnum cases and found that both failed at about the same pressures - that is, 65,000 psi (CUP). PO Ackley concluded that there was no design advantage of the belted-magnum case over the traditional 30-06 style case - given that both are made of equivalent quality brass.

Also, because the internal diameter of the 30-06 style case is less than both the belted-magnum and 300 RUM cases - given the same internal pressure - there will be more bolt thrust and chamber wall tension created in the larger diameter cases. Actually the 30-06 style cases are intrinsically safer than the larger diameter cases.

Hey AIU, Apparently you meant this for someone else, cause I don't believe I was in this part of the discussion.
---

Concerning the Belted Magnum Cases, I do see a particular advantage for them in some rifles like the Controlled Feed M70s. Here the M70s Gas Handling characteristics are poor when compared to Push Feed rifles. The last time I bothered to "section some cases", the Belted cases were indeed thicker in the Casehead area and that would be a benefit for anyone with a "Fixed Ejector" design rifle.

I've not sectioned any of the new WSM cases, but some of the other folks on this Board have and mentioned the Casehead area on them is "thicker" than a regular cartridge. I do not know if that is true for the SAUM cases, nor have I sectioned a RUM.

I understand your point about "Thrust" relating to Casehead Diameter, but really have no desire to enter that discussion. Way too many people offering opinions, as facts, that really do not understnd Internal Ballistics.

Best of luck to you.

Hot Core,

I can't see how the data is worthless even if any calibration problems meant the pressure readings were incorrect.

Firstly, their pressure readings are independent of brass hardness.

Secondly, they make can make pressure comparisons of different loads where pressures are too low to register differences on brass.

Thirdly, they are gaining additional data and like all data it will be subject to interpretation. However, for the intelligent and experienced handloader he must gain if addditional data is available.

Mike

quote:

Originally posted by Mike375:
Thirdly, they are gaining additional data and like all data it will be subject to interpretation. However, for the intelligent and experienced handloader he must gain if addditional data is available.

Hey Mike, Go read the post from "popenmann" about the Secondary Pressure Spike on his 30-06. Then look at the post above by CDH concerning First Hand vs Second Hand information. But, don't even bother to waste your time on the resident Lier's posts.

The last time I read through the 30-06 Thread, the author mentioned words to the effect that he is "ignoring the data" that his HSGS is providing to him. He mentioned(I believe) that he had not Calibrated the HSGS. And when I quit looking, he was speculating on running some experiments with a plugged barrel.

So, though I agree with the highlighted portion of your post, it is quite apparent there are still plenty of folks who got sucked into buying a HSGS, don't have the slightest idea on how to do a proper Set-Up, don't understand the importance of doing a Calibration to a Known Standard, and then once they get their "data(?)" ignore it or improperly justify continuing to use and quote that data.

Overall though, I agree with what you said, but there are more exceptions today created by the false impression that a HSGS is the answer for all reloading pressure concerns. Fortunately even the Beginners can read through some of this foolishness and see it for themselves. So, I guess it depends on the particular HSGS user.

As for me, it is perfectly clear what I've said all along is still true:

A HSGS (which has not been Calibrated to a Known Standard) = Reloader's Pyrite (aka Fool's Gold)

quote:

As for me, it is perfectly clear what I've said all along is still true:

As long as you maintain your zero actual experience status, it will always seem so to you. The rest of the world moved on long ago.

A newer, probably better explanation of secondary spikes has been posted on the other thread.

HC, have you read some of the BIZARRE putative explanations for the secondary pressure spikes in the "popenmann thread?" Much of it reeks of science fiction - that is, right from the script of the Starship Enterprise.

Popenmann showed a secondary spike to over 107,000 psi - yet, popenmann reports that the brass from these "events" reloads up to 30 times. Obviously, the brass didn't experience this high pressure. Why? - because the pressure spike didn't happen.

Most posting on this thread ignore this fact (yes, this is a piece of data), as well as the observation that the piezo electric systems don't record these secondary spikes (yes, also a piece of data).

You know what they say, garbage in garbage out. To me the whole secondary spike phenomenon must be an engineering glitch that needs to be worked out.

hot core
what does HSGS stand for?

this should wrap this is...

This is EXCESSIVE pressure

-

OK, AIU, just for your benefit, I'll post it here, too:

quote:

Denton,

I went part way down that road way back at the beginning since a moving plasma can generate an electric field. I determined at the time that the electric field created would not be nearly big enough to cause the effect we were seeing. Since the secondary pulses I was seeing were happening before the bullet exited the barrel, I eliminated what you are thinking of from further consideration. I had to go with something that could cause the problem in all cases not just some subset.

And we do see "mangled" brass. The brass from my 243 AI was blown out and ruined (loose primer pocket) by the huge pressure pulse with just one shot.

A Chemistry Explanation

I guess you didn't get the information from the ammo manufacturer in Virginia. Whoops. He was a chemist who got sick of the rat race. Now he makes custom ammunition for people who don't want to take the time themselves. Apparently it's fairly lucrative.

Anyway. He wanted to understand secondary pulses. He set up a microwave radar reflected down into the barrel. When he shot he was able to determine bullet position during the entire event. The bullet then went through the reflector.

He correlated the data and found where the bullet was when the secondary pulse occurred. He drilled a hole in the barrel behind the bullet position and sampled the gasses in the barrel during the secondary pulse with a gas chromatograph.

I don't have the exact gas breakdown. He may have sent it to Jim. (We had hoped to make contact with him at the SHOT show but it didn't work out.) I do remember that the gasses in the barrel when the secondary pulse is just starting has a nitroglycerine content 300% above what it started with. It's this atmosphere that is about to blow up and create the secondary pulse.

He found definite correlations between the type of powder used and the volumes of the explosive gasses. Ball powder was the worst.

He believes that he can explain secondary pulses strictly from a standpoint of chemistry. What he says dovetails nicely with the Catch Up theory.

I also have new information that says the reason the piezoelectric system does not "see" the secondary spikes is that they look for a downslope in pressure, and when they see it, they stop taking data.

So, the net of all this is that the secondary spikes are a real phenomonon, they do mangle brass, and the do blow the tips off some rifles, and impress rings in the barrels of others. There is now a very plausible hypothesis of why they happen.

Earlier systems, including Oehler, did detect them, but deliberately suppressed them, because they didn't fit with the designer's concept of what he ought to see.

AIU, I'm so pleased to see you citing data now. I think it is quite possible for us to have a very pleasant and useful conversation. The particular discipline that I came up through involves friends very thoroughly challenging each other's theories and concepts. I am very accustomed to that approach, and am glad to shed an idea that does not survive a collision with reality. Truly, if you challenge one of my ideas, and it falls, I will thank you.

Oh... Star Trek was a documentary.

Jeff, that gun you show was blownup with an excessive charge of H110 that had been mistakenly substituted for H414. Yup, over charges of fast burning powders are very dangerous. Best to make certain you're putting the right powder in the case.

Oh, that makes good sense - Oehler suppressing potentially life-threatening observations so they can avoid law suits and stay in business. Which business school did Oehler learn this practice at? But, maybe they saw secondary spikes as an anomalous engineering glitch in the "stretchy" PSI systems. Hmmmm.

quote:

Originally posted by Ackley Improved User:
HC, have you read some of the BIZARRE putative explanations for the secondary pressure spikes in the "popenmann thread?" Much of it reeks of science fiction - that is, right from the script of the Starship Enterprise.

Popenmann showed a secondary spike to over 107,000 psi - yet, popenmann reports that the brass from these "events" reloads up to 30 times. Obviously, the brass didn't experience this high pressure. Why? - because the pressure spike didn't happen.

Most posting on this thread ignore this fact (yes, this is a piece of data), as well as the observation that the piezo electric systems don't record these secondary spikes (yes, also a piece of data).

You know what they say, garbage in garbage out. To me the whole secondary spike phenomenon must be an engineering glitch that needs to be worked out.

We are in complete agreement. That is some of what I was refering Mike375 toward in my above post.

I really try to avoid discussions of that nature once it is Totally Obvious most of the posters are "randomly guessing" rather than making "experienced speculations" based on a good Engineering Background and Hands-On experience. You end up trying to "discuss" the issues and then a fool (like the resident Lier) hoses up the thread so bad with his complete lack of understanding concerning Internal Ballistics, that it simply degrades to arguing over nothing.

The bad part is there seems to always be some "New Guys" which get duped into believing the loonacy.

You had a good thread going here for awhile that people could actually learn from, darn shame it has skewed.

That's a l-o-n-g stretch, AIU.

And nobody has believed anything Hot Core has said in a long time. He contradicts NIST on calibration, contradicts Ken Waters on PRE, contradicts Ken Howell and OKShooter, and he contradicts the repeatability data from the strain gage/PRE experiment. In his mind, he's right, and the whole rest of the world is wrong.

excessive pressure is when you are pulling the bolt out of your ass and the remains of the barrel out of your ear.

quote:

Originally posted by bglenn:
hot core
what does HSGS stand for?

That would be a Home Strain Gauge System(HSGS), either the RSI Pressure Trace or the Oehler M43.

I do disagree slightly with the IMR/Hodgdon Experts by believing either of the above "has the potential" to provide some useful data. The problem is that most of the "users" don't know enough about them to realize a "Set-Up" is different from a "Calibration to a Known Standard".

Once it is properly Calibrated, then I believe it is appropriate to refer to it as a potentially useful Strain Gauge System(SGS). But, that is also dependant on the person doing the using.

What will be the most enlightening to you is to go back to the other Thread (or begin a new one) and ask all the HSGS lovers how they "Calibrate" theirs. To my knowledge there are two folks on this Board(besides myself) that have the correct answer, Sean and Lawndart(aka JCN). Also ask anyone in a Manufacturing Plant, Trade School or University about how Calibration is done. Compare the answers and believe who you think it correct.

As you can see in the 30-06 Pressure Spike thread, popenmann is seeing some very strange Pressures with his HSGS. And he has chosen to "ignore" what his HSGS is telling him. Now, you decide if the problem is with his HSGS, with the user, or maybe both.

But the key thing to remember is, there really is no need for the average Reloader to have a HSGS, other than stimulating the economy a bit when they are purchased.

That said, if you want wires hanging off your firearm in the way for you to fall over, a Strain Gauge glued to the Chamber area to screw up the Bluing, or positioned underneath the stock so the bedding can be goofed up, you desire to spend $1500 on a fine Laptop to run the equipment, and once you get the "data" it is just going to be ignored, then it is perfect for you.

A HSGS (not Calibrated to a Known Standard) = Reloader's Pyrite (aka Fools' Gold)

quote:

Originally posted by Ackley Improved User:
Oh, that makes good sense - Oehler suppressing potentially life-threatening observations so they can avoid law suits and stay in business. Which business school did Oehler learn this practice at? But, maybe they saw secondary spikes as an anomalous engineering glitch in the "stretchy" PSI systems. Hmmmm.

Oh good gosh, now you are going to confuse the resident Lier with "Logic".

HC,

You likely agree that engaging in an unending vitriolic post/riposte over the tracer PSI systems is silly. (Its becoming like the Hatfields v. the McCoys.) I doubt anyone will change their opinions regardings these systems and the secondary spikes. Usaully people just dig their heels in during an argument.

Like you, I concur that the tracer PSI systems leave much to faith given that there are no internal calibration and quality control standards. I feel much better when I can put a measurement system to an actually test of known amount.

In the meantime, I plan to chronograph and monitor the brass case (BUP) for signs of excessive pressure - setting that as my upper limit of PSI for load development. Moreover, I'm going to monitor estimated internal PSI with the NECO internal ballistics program, which I've found remarkably predictive of velocity - given powder type, powder charge, barrel length, and bullet wt./type. Indeed, the corresponding PSI predictions fit quite nicely with reports from a sundry of professionals and publications of PO Ackley. I've spoken at length with ballisticians from Nosler, Hornady, Speer, Sierra, and IMR/Hodgdon. They have been willing to visit at length and all say about the same thing, comments which I've reported on this thread.

Why don't we stick to the topic and ignore/forget the invectives - nothing much is accomplished. What do you think?

Regards and safe shooting, AIU

Hey AIU, I have Load From A Disk by Wayne Blackwell and it is much simpler than the NECO Program(as I have been told by folks who have both). The folks who have the same program you have all think very highly of it.

Mr. Blackwell's is based around the formulas of the Powley Computer and has surprised me in the past about how close it was able to predict velocity.

Having worked for years with many Mathematical Models, I really expected the Calculated results to vary from the Measured by more than they did. But, being leary of their predictions, I still watched closely for Pressure Indicators. And I still believe if I had done a larger "Sample Size" by Calculating more results over the years and then verifying them, the predicted values would have opened a bit more than I usually saw.

The problem as I see it is there is no way in any of the software to account for dimensional variations in Chambers, Barrels, Bullets and the varying strength of Primers and Powder from Lot to Lot. They all have to just "Average it out" within the Model.

So, I got the most pleasure out of my LFAD by running the old, "What if I....", kind of changes through it and plotting the results. Lots and lots of plots brought me full circle to a high appreciation of good old Standard Cartridges at their SAFE MAX levels.

One of my old buddies just sent me an email today describing what he is going through in turning some 300WSM cases into 325WSMs. I'm just not interested in all the aggravation of that kind any more.

Strayed a bit there. But, yes indeed I like the Ballistics Software to "play with", but I still don't put total faith in the results.

HC,

I agree the NECO internal ballistic program is nothing more than an approximation. Yet, by playing with it (changing various parameters), one can get a pretty good sense of what's important in maximizing performance, while maintaining a safe PSI. It's a learning experience working with the program. It's amazing how well the "old cartridges" stackup against the "latest-and-greatest" when they are loaded to equal pressures in equivalent guns.

Actually, I believe this program might be used to create a "reasonable" internal standard for calibrating and testing the strain-gauge PSI systems. For example, if Oehler were to buy up a large amount of one lot of a standard powder (say H4350), as well as large number of standardized primers (the same lot of Federal match-grade primers), and standardized bullets (match-grade Berger bullets of identical design, yet different calibers). These standardized components could be made available to strain gauge users in small amounts for making calibrating standard cartridges. Sold in small aliquots, the components would last a long time for many different users.

Next, one should then be able to determine the amount of that standardized powder per gram of H20 case volume & barrel length, while using the standardized primers and bullets, to calculate from the NECO program the expected muzzle velocity and corresponding maximum chamber PSI. [Before hand, with rounds loaded with these same components the NECO program would be calibrated against state-of-the-art piezo electric system - say the IMR/Hodgdon system.]

The strain gauge user would then load some of the standardized rounds at anticipated low and high velocity (low and high pressure) and measure velocity with a first-rate chronograph. The user would then know from the measured velocity what the highly probable maximum PSI was from the NECO program - and use this to calibrate his strain gauge system! Finally, the user could create reloads with the some components to fall inbetween the high and low, measure velocity, read PSI from the NECO program, and see if it correlates with the strain gauge reading.

Although not perfect, this system would likely yield more reliable data than they're getting now. What do you think? - am I crazy?

Regards and good shooting - AIU

That is an excellent idea. They could actually just make the ammo, have it Certified by SAAMI and sell it with a Calibrated "Average" Pressure.

Only problem I see is they have apparently never stressed the need for Calibration to a Known Standard. Apparently they really don't care if the folks that buy them ever get one in Calibration or not.

There are two other folks on here who have also come up with workable concepts. One posts as Lawndart and intends to send samples to SAAMI to get a Benchmark Standard for his test barrels. At that point, he could then begin selling Calibration Ammo as verified in relation to his SGS.

And a fellow named Sean has a method that anyone can use today. He bought a box of Hornady Ammo and got the Lot# off the box. Then he called Hornady and told them he was trying to Calibrate a HSGS and they were glad to provide the Average Pressure of that Lot to him from their records.

I'd asked some Win and Rem folks about that same exact data on two separate occassions and they declined to provide the information. Perhaps they would do so today.

Obviously a small nitch market for Certified Calibration Ammo. Darn shame the folks at Oehler and RSI can't figure out that it would be "easy profit" to provide it.

quote:

Although not perfect, this system would likely yield more reliable data than they're getting now.

It might, but the response of steel to pressure is already extremely predictable and repeatable. Whatever feat of calibration a person carries out, no measurement system will ever be better than its repeatability. If you can't get the same response to the same input (repeatability), all is lost.

Repeatability is measured as the standard deviation of the random error in the measurement system. This figure of merit is usually designated as the Greek letter sigma, with a subscript e. Lower is better, and I usually use sigmaE as the name, when I can't do Greek letters.

Anyway, from published data, sigmaE of the CUP system is equivalent to 1,827 PSI. The sigmaE of published piezoelectric data is 1,366 PSI. That is inflated by a systematic error in the SAAMI procedures. If SAAMI would control one variable that they don't, their sigmaE could drop as low as 422 PSI.

IIRC, the sigmaE of the PressureTrace system is 667 PSI, which is better than published piezo data. The old Fabrique Scientific strain gage system wasn't as good as the PT, but was in the 1,400 PSI ballpark. The PT is simply better designed.

SigmaE for the PRE method is about 6,800 PSI.

That's all from experimental and published data.

Denton, you're Bramwell - correct? Hard to imagine someone stealing his name for this form. You must have correlated the predicted PSI from the NECO internal ballistics program with your measured RSI stain gauge value - what did you find? Aren't you curious?

Can you provide a regression plot of NECO PSI vs. RSI Strain-gauge PSI? What is the linear regression equation with R2 value?

Also,I know you understand my point about, if 270 SAAMI max is 65,000 psi then why not 30-06 having a SAAMI max of 65,000 psi - that is, given equivalent gun quality.

HC, I think it would be much easier for RSI or Oehler to sell the standardized components than make the myriad of available calibers - that is, let the reloader make his own calibrating and standardizing rounds.

The system I'm suggesting could be adapted to any calibler, if the reloader knew the case volume in grains of H20. (This should be easy.) A standard powder charge would be equal to the std. grs of same-lot powder per gr. of H20 times case volume in grs of H20. That powder charge, plus a standardized match-grade primer, plus a standardize bullet type (maybe a match-grade solid construction Barnes bullet would be best) should yield a standard PSI maximum and velocity (per inch of barrel).

By chronographing the true velocity of the standard round, the strain gauge user should be able to correct for non-standardized barrel-related issues (i.e., small differences in rifling, barrel wear, throat length, small differents in diameter, etc.) by using the NECO program. But, it wouldn't have to be the NECO program; it could be a simple correction table provided by RSI or Oehler.

Denton could test his confidence directly in the strain-gauge approach by measuring some standardized loads. He's always asking for DATA. I'd like to see that data. Also, he needs to fix the engineering glitch causing the secondary ignition BS.

But, this standarized component approach is not likely to happen - surely I'm not the first to consider it. (This is not rocket science.) Besides, you better have your S**T together when it comes to preparing and selling "standardized" components. Otherwise you're going to be looking at the inside of a court room and paying massive lawyer fees.

Yes, that's me.

Haven't run strain gage against NECO, yet. I haven't paid a lot of attention to pressure predictive programs. The ones I have seen use IMR powders, which are good stuff, but just not what I usually use. Also, you'd have to use powders from many lots to do a decent job of characterizing repeatability. You have chamber to chamber differences to deal with, as well. It's messier than it looks.

Am I curious? Incessantly.

Yes, there are some SAAMI specs which I think are far too conservative for strong actions. I know of no reason that a modern 30-06 cannot be run at 270 pressures, though I generally can get all I need below 60 KPSI, and tend to operate there. (If it really worries people, I guess they could form their 30-06 brass out of 270... )

There are calibers can be safely run at pressures above SAAMI. The 8x57, 6.5x55, and 7x57 are examples. I run my 8x57 LR Mauser at about 55-56 KPSI, and my custom 6.5x55 at about 58.

However, for the most part, I figure SAAMI pressures are the economical operating point, unless I have a very sound reason for deviating from that.

quote:

Also, he needs to fix the engineering glitch causing the secondary ignition BS.

The secondary spike is really there. It is definitely not a glitch in the system. It's easy to make it come and go by changing components.... always there with component A, never there with B, exact same setup of the PT, shots fired minutes apart, and it never interferes with measurement of the primary peak. If you haul an oscilloscope to the range, you'll see the same thing, except that you can see when the gage goes into compression.

And, anyway, it's not my design, or my product, to do anything with. It's just a lot more convenient that hauling a scope, RV battery, and inverter around to do the same thing.

quote:

ireload2, the 222 case is a smaller diameter case and therefore, given the same internal pressure, there will be less bolt thrust and less chamber wall tension created when compared to the larger diameter cases - do the math (force = pressure x area). There is less area inside those smaller diameter cases.

AIU you just don't get it do you?
The case is going to be the first thing to fail in a modern bolt gun. Who cares about the "bolt stress and the chamber wall tension" if the Mickey Mouse case head blows out and blinds you.
By your reasoning a .222 case is safer than a 30/06 case. Yes the .222 case delivers less bolt thrust but it is a weaker case and is loaded to lower pressure than say a .25/06 or a 6mm Rem. No it will not blow the bolt out of a M700 but it might blind you quicker because the case will not take the pressures you seem to be after.

ireload2, looks to me like SAAMI has pretty good confidence in the strength of .222 diameter type cases - their SAAMI Max are right up there with many calibers of larger diameter.

.222 Remington SAAMI Max = 50,000
.222 Rem Mag SAAMI Max = 50,000 cup
.223 Remington SAAMI Max = 55,000
.250 Savage SAAMI Max = 45,000 cup
8mm Mauser SAAMI Max = 35,000
.257 Roberts SAAMI Max = 54,000
.351 Win SL SAAMI Max = 45,000 cup
.35 Whelan SAAMI Max = 52,000 cup
.284 Winchester SAAMI Max = 56,000

How do you explain this? 50,000 CUP is ~60,000 psi.

Denton, the NECO progarm has almost every bullet, rifle/pistol powder and rifle/pistol caliber you can think of, including the entire ADI line and others I haven't heard of - it's an international program. I'm told developed by a German ballistician worth his salt. I'm surprised you haven't looked at it - at least out of curiosity.

I may give it a try. Thank you for suggesting it. I was not aware that there was a product that covered that much variety.

Right now, it's 10:30 p.m., and I'm just wrapping up from my day job. So it may not be very soon.

If I get any interesting results, I usually report them, whether they contradict or support something I've said.

Do you know if it is designed to reproduce the pressures of a test barrel (generally minimum cut), or a typical chamber? Significant difference.

BTW, Hodgdon uses special lots of powder that fall right in the middle of their spec for load development. Lot to lot variation is significant, so that, and chamber to chamber variation will probably be the limiting factors in repeatability... but may not be too bad.

quote:

Originally posted by Ackley Improved User:
Denton could test his confidence directly in the strain-gauge approach by measuring some standardized loads. He's always asking for DATA. I'd like to see that data. ....

There is a serious problem with this idea. I can tell you for absolute certainty any "data" gathered by the "specific method" you outlined will result in totally skewed and worthless info.

Back a few posts ago you mentioned:

quote:

You likely agree that engaging in an unending vitriolic post/riposte over the tracer PSI systems is silly. ... Why don't we stick to the topic and ignore/forget the invectives - nothing much is accomplished. What do you think?

By complying with this request, I can not clearly explain why there is "Zero Chance" of getting useful input.

Best of luck to you.

Denton, why don't you post a range of specific strain-gauge pressures you've collected over the years. If you provide corresponding barrel length, caliber (preferably case volume in grs. of H20), powder type, powder charge, and bullet types (grs., brand, flat-base, boat-tail, etc.), I can run the NECO program and get some matched data pairs for linear regression. What do you say?

Sure. I'll look up some suitable data sets. It will be a few days, but I'll do it.

Sources of error that we need to be aware of:

"Typical" chamber vs. pressure barrel chamber (roughly 2%)

Lot to lot variation in powder (fairly large)

I load .030" off lands vs. standard COL (perhaps the program accounts for that)

quote:

Originally posted by Hot Core:

quote:

Originally posted by Ackley Improved User:
Denton could test his confidence directly in the strain-gauge approach by measuring some standardized loads. He's always asking for DATA. I'd like to see that data. ....

There is a serious problem with this idea. I can tell you for absolute certainty any "data" gathered by the "specific method" you outlined will result in totally skewed and worthless info.

Please pardon me for jumping in here, but "skewed" and "worthless" are two entirely different concepts when measuring pressure for the purpose of avoiding traumatic expansion.

If I understood correctly a discussion Denton had some time ago, I think with a lurker named Avanti, the HSGS that Denton was defending was "calibrated" by ascertaining that the HSGS did not not "pass" a load any hotter than user-selected factory rounds, presumably meeting SAAMI specs. While this is not exactly calibration, and certainly provides skewed data, they are skewed and maybe even truncated in favor of safety. While these data may require some understanding, I doubt that they are useless.

JM.02W

quote:

Originally posted by Ackley Improved User:
ireload2, looks to me like SAAMI has pretty good confidence in the strength of .222 diameter type cases - their SAAMI Max are right up there with many calibers of larger diameter.

.222 Remington SAAMI Max = 50,000
.222 Rem Mag SAAMI Max = 50,000 cup
.223 Remington SAAMI Max = 55,000
.250 Savage SAAMI Max = 45,000 cup
8mm Mauser SAAMI Max = 35,000
.257 Roberts SAAMI Max = 54,000
.351 Win SL SAAMI Max = 45,000 cup
.35 Whelan SAAMI Max = 52,000 cup
.284 Winchester SAAMI Max = 56,000

How do you explain this? 50,000 CUP is ~60,000 psi.

Actually,

There are dimentional variations between the various 222 type caseheads. If you section a 222 Remington case and compare it to a 222 Remington Mag case, then you'll see why the latter has a higher pressure rating. Similarly, 300 Mag is much stronger in construction than a 30-06.

quote:

Originally posted by Recono:
Please pardon me for jumping in here, but "skewed" and "worthless" are two entirely different concepts when measuring pressure for the purpose of avoiding traumatic expansion.

If I understood correctly a discussion Denton had some time ago, I think with a lurker named Avanti, the HSGS that Denton was defending was "calibrated" by ascertaining that the HSGS did not not "pass" a load any hotter than user-selected factory rounds, presumably meeting SAAMI specs. While this is not exactly calibration, and certainly provides skewed data, they are skewed and maybe even truncated in favor of safety.

Hey Recono, No pardon needed, dive right in.

You managed to miss "my" point, but did make some additional excellent points about why the data will be worthless --- no make that totally worthless.

It is simply impossible to do a real "Calibration" with an unknown. And when you said "presuembly", that obviously means the actual Average Pressure of that ammo was unknown. Therefore, the HSGS was not Calibrated and the data is not only totally worthless, but potentially dangerous if it gets passed about as if it had any worthwhile value.

This is EXACTLY the kind of illogical loonacy that got people quoting, "Velocity = Pressure" over the past few years, which is DEAD WRONG! Poor understanding of the issue, poor data gathering, data skewed to fit an improper agenda and people who "thought they understood" passing along bad info.

quote:

While these data may require some understanding, I doubt that they are useless. ...

I'll bet you are familiar with the phrase, Garbage in = Garbage out.

Feel free to quote me when I say:

quote:

Therefore, the HSGS was not Calibrated and the data is not only totally worthless...

Still at odds with NIST, I see.

Nobody but you has ever suggested that a strain gage system is calibrated to an unknown. That's your own little fantasy, which you keep repeating, and that nobody but you believes.

If your childish and naive view of calibration were correct, we could not calibrate speedometers in cars, we could not know the mass of an electron, and we could not know the distance to other galaxies. Yet we do.

If your childish and naive view of calibration were correct, CDH could not routinely measure PSI within .02% in his work, without reference to a PSI standard. Yet he does.

If you can write an equation for the output of a measurement device, that expresses the output in terms of known quantities, then the output is calibrated. That's per the NIST Handbook. Through the Hoop Strain Equation, and Hooke's Law, you can do that with a strain gage. The NIST traceable quantities you have to supply in the equation are three critical dimensions.

Or are you once again maintaining that measuring with digital calipers is "just a guess" at the dimensions?

No wonder nobody believes you anymore.

Or do you believe the line from Brave New World, that 63,124 repetitions make a truth? If so, you have to repeat your silly notion about another 62,000 times to overturn NIST.