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A single 'calibration' point is WORTHLESS!

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Hey CDH, That is an interesting thought on the situation. I do understand what "you" are talking about.

But, getting "at least one point" of Calibration is to me better than no Calibration at all.

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For example: Assuming your theoretical offset of 2000 PSI between a SGS and a SAMMI test barrel with the same ammo for your 30-06, and SAMMI barrel gives 50kPSI, there is a strong reason to believe that the difference at 40k or 60k PSI is NOT 2000! Hence the reason it is called a calibration CURVE...

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Good points, especially with a HSGS.

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At best, it is what is known as a (technical term) cal. check, but never a calibration. And don't hammer me for semantics, this is a very critical point if one is to really call something calibrated.

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No semantic hammering from me. I also can see your point here.

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why I can't get my old .280 to shoot like it used to?

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What is it doing different?

Maybe you need to stick a "Pre-Calibrated HSGS" on it! HAHAHAHA

If you do, let me recommend you stick the Strain Gauge directly across the muzzle and tape it in place. At least that way it will keep Pine Needles from falling in the barrel and actually provide a useful service.

Best of luck to you.

This all started a year or so ago, when the repeatability of PRE was being discussed. Not knowing how repeatable PRE was, several of us decided to run an experiment, to find out. We invited Hot Core to participate, in a way that nobody could question the authenticity of his data. Hot Core would have no part of it. No, he "knew" that PRE worked just fine, and was not about to take part in any such test. The results came in unfavorable to PRE, and this discussion has been going on ever since.

Someone then compared Hot Core's version of PRE with the original Waters version, which Hot Core claimed to be teaching us all. Big discrepancy. What Hot Core was doing wasn't even the real Waters method.

Since he has no data, and doesn't like what the actual data says, and his ridiculous arguments routinely get pounded to dust, he has to keep inventing ever more ridiculous objections. If he keeps on doing that, he doesn't have to admit he was wrong. He apparently thinks that is more face saving than what he's doing.

Hot Core, just accept the data. Rigorous experiment says PRE has poor repeatability, and that strain gage systems are highly repeatable. Calibration is right out of the NIST manual, as is the indirect calibration for commercial piezo systems.

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Originally posted by Hot Core:

Here we were talking about using half a box of Factory Ammo to see what Pressure the HSGS would think it is in that rifle. Then the other half is sent to SAAMI for them to see what the same Ammo from the same Lot does in their Certified Barrel. Once they provide a report to you about the exact Pressure that Ammo provides, then you can determine if your HSGS is reading Low, correct or High.

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Wow Hot Core, listen to what you are saying, "Once they provide a report to you about the exact Pressure that Ammo provides,...". Apparently, you are under the incorrect assumption that ammo (factory, referance, or handloaded) will create the same pressure no matter what chamber or barrel it is fired in.....that is the only way you could "calibrate" using this method. The pressure this ammo created in the test barrel has nothing to do with the pressure created in the barrel with the HSGS attached! You yourself agreed in an earlier post that if the same ammo was fired in indentical barrels save one chambered Min spec and the other Max spec, less pressure would be created in the Max spec chambered barrel. Now you are saying no matter what pressure is measured in the test barrel, accept it as the pressure that will be generated in any barrel this ammo is fired in (rough bore, worn throat, min spec chamber, max spec chamber, under tolerance barrel, over tolerance barrel, etc.) I must believe you know you are off base here but can find no way to get out of the debate without admitting you are wrong.

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We "calibrated" by adding a 2,000 lb adjustment factor (based on comparison to the SAAMI barrel pressures). Adjusting the HSGS reading caused us to go from an accurate measurement to an inaccurate one. The "calibration" made us think we were measuring low......when actually we were right on the money with our pressure measurement. I'm thinking this proves that a scenario does exist where "calibrating" to referance ammo can lead to inaacurate measurements. Agreed?

AND HOT CORE'S RESPONSE

No. I really don't see any use in going farther. You have overlooked or chosen to ignore most of the thread.(I do that with some of the posters here too.)

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That is the kind of answer I would give ....... if I had no answer to the question!!!

We fired referance ammo in both barrels and (using the method you promote) determined the actual pressure in the test barrel was 60,000 psi and only 58,000 psi in the other barrel so the adjustment was to add 2,000 psi to the reading on the HSGS. Now we place the HSGS on the test barrel and obtain a reading of 60,000 psi, exactly the same as the actual and true pressure measured by the other system. But now, according to the system you, Hot Core, promote, we must add 2,000 psi to the correct and accurate reading to give an incorrect and inaccurate reading of 62,000 psi!!! This is the best "calibration" you can come up with???

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And finally Hot Core, in a previous post you were whining and crying how no one would discuss the issues but wanted to name call or make derogatory comments or some such nonsense. Well, listen to your last post toward me:

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Quote From Hot Core:

You either missed some of the posts or your blind faith that Calibration is not needed is skewing your thoughts:

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And another:

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Quote from Hot Core

This next comment from you indicates to me that you simply didn't follow the flow of this discussion, or you really just don't understand what is going on. But, it is apparent in this thread that you are certainly not alone.

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Well, I think it's apparent that there is indeed someone who doesn't understand what is going on in this very thread.

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Hey HogWild, I'll try to explain why I said "you simply didn't follow the flow of this discussion, or you really just don't understand what is going on."

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Wow Hot Core, listen to what you are saying, "Once they provide a report to you about the exact Pressure that Ammo provides,...". Apparently, you are under the incorrect assumption that ammo (factory, referance, or handloaded) will create the same pressure no matter what chamber or barrel it is fired in.

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No, as you correctly state later on and what I did say is that there will be a difference in Pressure between firearms, even if the barrels are as exact as possible.

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....that is the only way you could "calibrate" using this method.

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I either said that, or I agree.

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The pressure this ammo created in the test barrel has nothing to do with the pressure created in the barrel with the HSGS attached!

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Totally WRONG!!! It has everything to do with allowing the HSGS user to properly Calibrate his device.

For some reason this is the part you seem to be having trouble with. In a "Final Effort" to explain it, I'll give one more Example for you. I'll even use a different Example in an attempt at avoiding confusion with the previous Examples.

1. You guess at the Chamber Wall thickness.

2. You glue a Strain Gauge somewhere close to where you think you measured.

3. You fire half a box of Reloaded Ammo that has your favorite Load (It shows the exact same Velocity you randomly selected from a Manual and therefore "leads you to believe" it is a SAFE Load.) in the firearm and "Average the Pressure".

4. Let's say in this Example(with made up numbers) that your super fine HSGS measured 50,000psi as the Average Pressure.

5. You record this Average Pressure so as not to forget it.

6. You send the other half box of Reloads off to a SAAMI Certified Test Lab and have them see what it records in a Certified Barrel.

7. Let's say in this Example(with made up numbers) that the Certified Lab measured 75,000psi as the Average Pressure of your Reloads. The SAAMI MAX for your cartridge is 62,000psi.

8. The Certified Lab sends you that information.

9. From the two sets of information you can see that your Reloads are Averaging 13,000psi above SAAMI Max. Knowing that, a person with good sense would realize that even though the HSGS says the Load is at 50,000psi, it is pulling a Clinton on you. The Reloads(using the exact same components) should be reduced until the HSGS records 37,000psi in order to be at a SAAMI MAX in your specific firearm.

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I seriously doubt the HSGS will be off that much, but since you are guessing at the Chamber Wall thickness, placing the Strain Gauge on a Double Ogive surface, the manufacturing variation from firearm to firearm, the manufacturing variation from Lot to Lot of components and the variations in the actual HSGS, it would be a real miracle if it was close to reality.

Without a proper Calibration(like the JCN HSGS Calibration Method) though, the HSGS user is simply guessing (again) that his information has any validity at all.

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I've no desire to discuss it further with you. If you understand that example, good for you. If you don't, best of luck to you.

By the way, the next response to Dr. Dan is not concerning you (HogWild) in any way.

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Hey Dr. Dan (the Head Shrink Man), It has been a long time since I last heard from you. Glad to hear you are having such good luck with the PRE/CHE Files I sent you.

I do see what you mean about the person who is "Obsessive Compulsive" with my posts. And yes I also realize he skews what I say in an effort to gain my attention in a negative way. That is why I quit responding to him last year.

No, I do not see the Stalker linkage, but then I'm not a Head Shrinker. Were you joking about "the other part"?

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1. You guess at the Chamber Wall thickness.

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Wrong. You measure the OD with a dial caliper, then measure the OD of a fired case, and add .001" to get chamber ID.

Hot Core, you make yourself look foolish when you make statements like that.

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2. You glue a Strain Gauge somewhere close to where you think you measured.

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Wrong. You put an empty casing in the chamber, drop a dowel down the barrel, mark the muzzle point on the dowel, take the casing and the dowel out, to mark the casing and measure it at the point where the strain gage is attached. That gets your ID at the right point. Measuring the OD at the gage is very easy.

Hot Core, you make yourself look foolish when you make statements like that.

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3. You fire half a box of Reloaded Ammo that has your favorite Load

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Wrong. This is a total fabrication. You obviously know nothing about how gage systems are actually used.

Hot Core, you make yourself look foolish when you make statements like that.

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7. Let's say in this Example(with made up numbers) that the Certified Lab measured 75,000psi as the Average Pressure of your Reloads. The SAAMI MAX for your cartridge is 62,000psi.

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Wrong. No cartridge has a peak pressure independent of the rifle it is fired in.

Hot Core, you make yourself look foolish when you make statements like that.

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I'm an EE myself.

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No you're not. Hot Core, you make yourself look pretentious, insecure, and underqualified whan you invent credentials for yourself.

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Originally posted by Hot Core:

9. From the two sets of information you can see that your Reloads are Averaging 13,000psi above SAAMI Max.

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No. From the two sets of information you can see that your Reloads are Averaging 13,000psi above SAAMI Max when fired in a SAAMI test barrel. You still don't know anything more about what peak pressure your reloads generate in your strain gage equipped firearm. Knowing that, a person with good sense would realize that anyone who tries to tell you that the SAAMI data from your reloads is useful in calibrating a strain gage to measure the pressure generated by that reload in your own firearm either doesn't understand the relevant physics or is pulling a Clinton on you.