Hot Core

Once again you demonstrate your inane inability to comprehend even the simplest of context of a sentence. Here is what you’ve now said and below it is what I really said in the thread (the one you cite). It is very obvious I said “killed elk†not “hunt elk†with a .223. Everyone will see what a blatant liar you are. (At least I spell it correctly when I refer to you, eh) Your blatant disrespect for LEOs is also obviously apparent and not even worthy of further discussion. You are an idiot.
What Hot Core posted;
“Originally by larry:
As usual, you state things out of contxt only to be arguementative and misleading. I never said I "hunted" elk with a .223. I said I killed elk with a .223. There is a big difference. I was a LEO in NE Oregon for many years and dispatched several injured elk most of which were poorly shot with much larger cartridges. I "killed" several of them with the .223.
Lets get this one out of the way since I saved a link to it - larry and the 223Rem on Elk. It will be found near the bottom of the thread after I'd mentioned larry's hero - teanscum - was using a 223Rem on Mulies. I'll let you all decide if the "context" of larry's comment led me to believe he was Hunting Elk or not.â€

So larry was a doughnut-eating, radar-runner for many years. That sure explains a lot to me.
Here is the actual quote of what I said in the thread you cite; “As to my "blood brother; what's to say? I've killed elk and deer with the .223. In some areas it is quite legal to do so. Deer are not really all that hard to kill. I've also gotten 3900 fps out of a 26" .223 with a 40 gr bullet. I used your CHE method and an old original lot of H414 (the new stuff won't do it). I wouldn't shoot those loads these days as the primer pockets wouldn't hold the primer on the next reloading. Your CHE showed no over pressure......hmmm something to be said there. I guess you'll come up with some sort of "reference ammo" that is used to calibrate the killing of deer now. That seems to be your droll style.â€

Pretty plain to everyone that I said; “I’ve killed elkâ€. So what part of that is “huntâ€, none. Everyone here can see that but you. I was right then and I’m right now, that is your “droll styleâ€.

Your further comments regarding Carcano91s questions are your usual droll and incompetent answer. They require no further discussion.

Larry Gibson

quote:

Originally posted by carcano91:
I will address elk hunting when I feel in the mood ;-).
In the meantime, I wish to thank Larry for his long and substantial answer to my posting. You have shown the same politeness that you have asked me for, and we might get a fruitful discussion going.

Merci, Carcano

Carcano91

I am most certainly looking forward to further fruitful discussions.

Larry Gibson

bartsche

"Some times my brain misinterprets and signals my key board to over-ride my ass hole."

That never happens to me

Larry Gibson

(*Whew. Finished now. Thanks for your patience!*)

Thanks for your input, Hot Core and Larry Gibson. I will try to incorporate your suggestions and criticisms in my answer, but forgive me if I might miss out on some.

quote:

Originally posted by Larry Gibson:
Appears that you, like Hot core make a lot of assumptions on what I do or don't do and how I conduct tests.

That could be - assumptions are not always consciously reflected, that is their trickiness -, but the only assumption that I immediately feel responsible for, is a hermeneutic assumption:
Namely my assumption that you had meant (and expressed) in your original posting to absolve the various dates of Turkish 7,92mm surplus ammunition in general from any shadow of cartridge-induced overpressure. It is correct that you had referred to those that you had tested, but I understood you to make a general statement in defence of all the Turkish surplus (since nobody before has said: "All Turkish ammo is dangerous", but rather only specific years and batches were in doubt).

quote:

You also seem to imply things that i did not. For example, you state in this post;
"You were wrong when deducing from the above facts that Turkish 8x57 IS military surplus ammunition which seemed to "exhibit pressure signs" (unreliable as those often are, as I concede) would in fact not have been overpressure.

As explained above via link, *some* batches of Turkish ammunition were found to exhibit far higher muzzle velocities, which is at least a strong hint to higher pressures. Velocity chronographing is no substitute for pressure test barrels, but is an important and very useful information, and no reloader should be without (at least access to) a chronograph."

Then in the later post;
"On page 2 of the same thread, Gerard Schultz also posted an important cautioning with regard to thuse judicious use of chronographs, as I had recommended:
Gerard Posted 12 May 2008 12:43
"The danger associated with blindly using a chrono and associating the speed with pressure is that, at the same speed, two different powders can give widely differing pressure levels. One may be safe and the other not. You will see we place the "do not exceed" speeds on our website in relation to specific powders and often the "do not exceed" speeds differ, within a caliber/bullet combination, for different powders."

First you say that chronographed results demonstrate over pressure in Turk ammo and that I am wrong. Then say and quote another to reinforce your point that the use of a chronograph is not reliable as an indicater of over pressure. So which is it?

Both. The conclusion only works in one direction, so one must distinguish:
- That a given load combination does not exhibit higher velocity than others (even than factory loads), does NOT infer that is safe; it might still have high pressure.
- On the other hand, a lot that is significantly faster out of the same gun with the same bullet and the same case will usually achieve (though not necessarily in every single case) this via higher pressure.
The two other exceptional factors are special bullet lubrication (molybden sulfide) and special (high-energy) powders from long barrels.

quote:

If you'll note in my post I stated; "Even the lot with 53,000 psi still gave the same "sticky bolt" opening as the higher pressure loads." The reason is because brittle brass does not "springback" like annealed brass. It expands and stays expanded. Sometimes it splits.

Hm. I am not sure inhowfar the employed adjective "brittle" cuts it. I would try to say that the question is one about a "window of elasticity". Brass must be properly annealed (in the right area) between too soft (then the case clings to chamber; typical for old copper cases, which today are not used anymore, except for 6mm Flobert and 4mm rimfire) and too hard (cases does not expand elastically in sufficient measure; either lets gas blow by, or will crack). Hardening can be a consequence of work hardening, of temperature changes, and sometimes simply of age (I gather this is much too simplified, and I will welcome any more thorough dissertation on he topic).

quote:

I also put the Turk load in W_W cases and the velocity and pressure was almost identical to the Turk case velocity and pressure. Yet there was no sticky bolt with the W-W cases.

This a helpful comparison indeed. In such a case, I would certainly agree with your conclusion that the brass is at fault.

quote:

Since you asked I'll explain and answer some of your other questions about the proper use of this "gimmick".

Thank you very much.

quote:

“a) Like any pressure measurement tool (indeed, like a copper crusher or piezo gauge), a strain gauge must be calibrated and re-calibrated before use. If not, it will only deliver relative data ("my loudenboomer eargehplitten handload, tailored to stop the most ferocious charging dik-dik in its tracks, delivered 50 % more pressure reading than the same caliber Remchester factory load").â€

Your assumption that it must be calibrated is correct. The M43 is calibrated at the factory when made.

I have not yet handled an M 43 and will thus not pretend I did ;-). However, I would believe that a strain gauge that is permanently affixed to curved tubular surfaces of varying thuickness (as here) must be calibrated on the object itself, as to reflect its expansion behaviour, and thus depict pressure value that are not tooooo far away from a pressure barrel?

quote:

As to the M43 needing to be “re-calibratedâ€, it is just not so. Perhaps you misunderstand this from Hot Core’s constant rants. Do you think that the ammunition makers “calibrate†their own pressure machines by adjusting something so when “reference ammunition†is fired the numbers from their pressure machine then are the same as what the pressure of the “reference ammunition†is supposed to be? There is no such thing a “calibration ammunitionâ€, it is reference ammunition

Yes, I was aware of the proper terminology (by reading your past postings) and I have tried to abide by it :-).

As to the calibration of measurement instruments:
The dimensions of test barrels change in the course of usage, and thus the pressures that are measured will slowly become lower. One can possibly make up for this (within limits) by adding a correction factor. To establish such a factor, reference ammunition can be helpful, I guess, just as you have kindly explained yourself in a later example ("Then when another ammunition maker fires it under those conditions but in their pressure barrel/machine and they get a psi 3,000 different they merely use that as an offset in the computation of pressure reading of other ammunition. Now as you state in “b†below this only tells the ammunition manufacturers what the pressure is in their one test barrel.").

As to the primary calibration, I agree that one would not need (and better not use) ammunition for this purpose, in the case of copper crusher cylinders (each delivery batch has its new tarage tables) and of piezo quartzes. But I do not know how the same purpose is achieved with a strain gauge.

quote:

They test their ammunition in that one test barrel to make certain the loaded ammunition is below the MAP.

To which statement I would like to add the observation - as evidenced in some circular test series of various proof houses the results of which were very quickly pushed under the carpet - that test barrels are often used for a long time. A too long time. In fact, the RUAG ballistician in Thun, when I visited factory and ballistic lab, did not fail to add one or two probably truthful snide comments about some state proof houses with eroded test barrels and correspondingly lower pressure readings.

quote:

Most companies then chronograph those pressure tested loads in production firearms with a nominal barrel length.

I believe I actually own one such gun, namely a m/94-14 carbine that probably came from the Norma factory. Condition, markings and wear marks are 100 % consistent with such continuous use.

quote:

You’d be surprised how many ammunition manufacturers use the Oehler M83 with strain gauges attached to these production firearms. The M83 is somewhat more sophisticated than the M43 and the m83 is a “laboratory†instrument as Hot Core likes to rant about.

I am not sure inhowfar I should be happy about that. A strain gauge fítted barrel is certainly a BIG improvement over merely looking at a chronograph and trying to guess something out of your case head, your primer or your tea leaves. Still, I wonder why not proper pressure barrels are used in these cases, though I am afraid I can guess the answer.

quote:

It is expected in these tests that the production ammunition will give less pressure in production chambers and barrels than it does in minimal spec SAAMI pressure test barrels.

For example I contacted Federal (very nice to talk to and very cooperative) and advised them of my about to be conducted tests with 3 different lots of their .308W ammunition. I gave them the lot #s and asked if they could tell me the psi of those lots when they pressure tested them in their SAAMI test barrels. With in 24 hours I had the answer and also was advised of the ambient temperature, the barometric pressure and the humidity. I waited for a day when the temperature would attain 70 degrees. The humidity and barometric pressure were close but not quite the same. When the ambient temperature had been 70 degrees for an hour I ran the test. With a relatively new barrel with minimum headspace the pressure I recorded were very near the federal test pressure only slightly below with the farthest off being 2100 psi. In the game of measuring pressures that is pretty darn close.

This is the sign of a very good, tight barrel in your gun (not far away from the minimum CIP dimensions), and/or of an only slightly used factory test barrel ;-). That was not really a joke; most factory test barrels have seen some honest use already, and are not always replaced at the drop of a hat. It also shows that your strain gauge is apparently quite reliable and trustworthy.

quote:

The psi of all those cartridges was where the published information said it should be.

I would doubt this. The "published information" as printed in ammo catalogues, on cartridge boxes etc. is almost always given higher than the *actual* pressure as measured in a test barrel, for the very reason that you had lateron agreed with. Maybe you meant that the specific individual *lot data* that you received e.g. from Hornady were close to your own readings?

quote:

“b) One properly would use specially loaded SAAMI or CIP reference ammunition to calibrate a strain gauge. Still, this will only tell you how the presure was in the *test* barrel, not in the specific gun's barrel. A load that will give 90 % percent maximum allowed use pressure in a test barrel (manufactured to CIP minimum specifications) may deliver 80 % pressure in your personal gun and its wider chamber. It might deliver 130 % in your benchrest barrel.â€

Who, other than Hot Core and now you, say “One properly would use specially loaded SAAMI or CIP reference ammunition to calibrate a strain gauge� The manufacturer doesn’t. The ammunition manufacturers I talked with didn’t.

Okay, see my comments to that above and below. I try to learn...

quote:

You are absolutely right in that a pressure test with a strain gauge “will only tell you how the pressure was in the *test* barrelâ€. However let us remember that the test pressure of SAAMI test barrels also only tells us what the pressure was in the test barrel. It does not tell you nor I nor anyone else what the pressure will be in our rifles. So what is the difference? Not much except that since my barrels are production barrels and not minimum spec SAAMI chambers/barrels then the pressure could vary between your rifle and mine, probably not by much based on my tests.

Okay, fully agreed.

quote:

I seriously doubt your thoughts of 130% over pressure above SAAMI MAPs would occur as SAAMI specs for pressure chambers and barrels are even more stringent than even most benchrest rifles. Besides building a custom benchrest rifle with minimal specs is not going to fired with factory ammunition, now is it. Let’s try to remain reasonable here, shall we?

Yes, my fault. Firstly the (fictional) overpressure of 130 % was probably quite overboard, 110-120 would be more realistic I guess. Secondly, I did indeed think of a custom.-made benchrest rifle with extra tight chenre neck that would not even accept factory ammunition with unturned necks, but I failed to make that clear and speak it out. I apologize for the omission.

quote:

"Psi†as used with strain gauges, conformal transducers and piezoelectric transducers (several types, ) are calibrated in their respective computers to give the same value of “psiâ€.

Calibrated? How so? A fixed strain gauge in universal receiver or any other technical receptable might be calibrated via hydraulic pressure; but how would any gauge manufacturer be able to do this when he does not even know how and where there gauge will be mounted, how thick (in the given case) the barrel walls will be etc.? I still do not quite understand the assumption.

quote:

What you and Hot Core don’t seem to understand is that is the case with EVERY method of pressure measurement. None of them measure the “absolute pressureâ€.

Hm, that seems pretty clear to me now in your explanation. The copper crusher measures the permanent deformation of copper cylinders (BTW fraught with difficulty because of the decisive influence of the grease used), the piezo electric transducer - much easier to handle - measures the temporarily different resistance of a crystal to electric current under pressure, the strain gauge measures the temporary stretching of the gauge (also via electric resistance, I believe).
The statement above to which you apparently refer, stems from Gerard Schultz, by the way, I had only quoted it.

quote:

Tests have demonstrated the use of the strain gauge (numerous ammunition manufacturers use them) give consistent pressure measurements in psi as do the other modern methods. Is that psi measurement only relative to that rifle/chamber? Yes, just the same as the factory pressure is only relevant to the test barrel/chamber.

Correct.

quote:

Bottom line is I’ve tested factory and handloads of several different cartridges in several different rifles of the same cartridges and found the variations in pressures to be within expected between pressure barrels. A load that is safe in one rifle has proven safe in another. That is the same result as the factories expect when they sell their ammunition.

This is indeed as should be expected. Test barrels should be CIP minimum, and thus RL rifles will likely exhibit less pressure.

Carcano

Carcano91

“Whew†is right! I shall try to cut to chaff here and respond to your answers (quoted). I will, for the most part, delete those where we are in agreement;
“Namely my assumption that you had meant (and expressed) in your original posting to absolve the various dates of Turkish 7,92mm surplus ammunition in general from any shadow of cartridge-induced overpressure. It is correct that you had referred to those that you had tested, but I understood you to make a general statement in defence of all the Turkish surplus (since nobody before has said: "All Turkish ammo is dangerous", but rather only specific years and batches were in doubt).â€

Probably my bad here; you are correct that I refer only to those lots of Turkish ammunition that I have knowledge of. I have shot several other lots than those mentioned and they exhibited the same “sticky bolt†extraction. I did not however test them as I did with those lots mentioned. It is entirely possible that there are some over pressure lots out there.

“Both. The conclusion only works in one direction, so one must distinguish:
- That a given load combination does not exhibit higher velocity than others (even than factory loads), does NOT infer that is safe; it might still have high pressure.
- On the other hand, a lot that is significantly faster out of the same gun with the same bullet and the same case will usually achieve (though not necessarily in every single case) this via higher pressure.
The two other exceptional factors are special bullet lubrication (molybden sulfide) and special (high-energy) powders from long barrels.â€

We agree, but I don’t think you quite explained it that way originally. I could be wrong but that’s not the way I understood your original explanation. However in the end here we are on the same page of the hymn book.

Hm. I am not sure inhowfar the employed adjective "brittle" cuts it. I would try to say that the question is one about a "window of elasticity". Brass must be properly annealed (in the right area) between too soft (then the case clings to chamber; typical for old copper cases, which today are not used anymore, except for 6mm Flobert and 4mm rimfire) and too hard (cases does not expand elastically in sufficient measure; either lets gas blow by, or will crack). Hardening can be a consequence of work hardening, of temperature changes, and sometimes simply of age (I gather this is much too simplified, and I will welcome any more thorough dissertation on he topic).â€

A matter of semantics here. Brittle brass exhibits the same characteristics as the Turkish brass; it expands but does not spring back like properly annealed brass. It also cracks and splits. Too soft brass, while it does not springback, does not crack nor split.

“quote:
I also put the Turk load in W_W cases and the velocity and pressure was almost identical to the Turk case velocity and pressure. Yet there was no sticky bolt with the W-W cases.


This a helpful comparison indeed. In such a case, I would certainly agree with your conclusion that the brass is at fault.
quote:â€

Thank you, once again we are in agreement.

“I have not yet handled an M 43 and will thus not pretend I did ;-). However, I would believe that a strain gauge that is permanently affixed to curved tubular surfaces of varying thuickness (as here) must be calibrated on the object itself, as to reflect its expansion behaviour, and thus depict pressure value that are not tooooo far away from a pressure barrel?â€

The instrument is calibrated by the maker who has the full array of pressure measuring devices. That is his business, he sells the pressure measuring instruments to the ammunition makers, he has been in business a long time. No one, except a couple individuals on this forum, doubt his credentials or the accuracy of his instruments. The strain gauges measure the expansion of the steel. Barrel steel has known expansion properties. Measurements are taken of the outer diameter of the barrel where the gauge is attached and on the inside of the chamber where the gauge is attached. With the known properties the expansion properties are then calculated. This is done with proven engineering principles.

“As to the calibration of measurement instruments:
The dimensions of test barrels change in the course of usage, and thus the pressures that are measured will slowly become lower. One can possibly make up for this (within limits) by adding a correction factor. To establish such a factor, reference ammunition can be helpful, I guess, just as you have kindly explained yourself in a later example ("Then when another ammunition maker fires it under those conditions but in their pressure barrel/machine and they get a psi 3,000 different they merely use that as an offset in the computation of pressure reading of other ammunition. Now as you state in “b†below this only tells the ammunition manufacturers what the pressure is in their one test barrel.").â€

As to the primary calibration, I agree that one would not need (and better not use) ammunition for this purpose, in the case of copper crusher cylinders (each delivery batch has its new tarage tables) and of piezo quartzes. But I do not know how the same purpose is achieved with a strain gauge.
quote:
They test their ammunition in that one test barrel to make certain the loaded ammunition is below the MAP.

To which statement I would like to add the observation - as evidenced in some circular test series of various proof houses the results of which were very quickly pushed under the carpet - that test barrels are often used for a long time. A too long time. In fact, the RUAG ballistician in Thun, when I visited factory and ballistic lab, did not fail to add one or two probably truthful snide comments about some state proof houses with eroded test barrels and correspondingly lower pressure readings.
quote:
Most companies then chronograph those pressure tested loads in production firearms with a nominal barrel length. “

I’ve no idea how long (how many shots fired through them) ammunition companies keep their test barrels. I do know that the M98 24/47 I am using was a factory rebuild when I received it. The barrel was new and other than proof firing I doubt it saw any use. I keep a log book on each of my test firearms and can tell you to the exact round how many shots they have fired. Yes barrel dimensions do change due to barrel wear. This does lower the pressure. I suspect somewhere down the line I shall see a change. I have stored different lots of several cartridges to use as my own “reference ammunitionâ€. Testing this ammunition as the barrel wears will give a good indication of what to actually expect. Also as I stated most companies then test those pressure barrel tested loads in factory firearms to ensure they reasonably meet factory specs. The factories know how many now have chronographs and know what the actual velocities are of their ammunition. The published ammunition specifications are much closer to reality than they were in pre-chronograph days.

“quote:
You’d be surprised how many ammunition manufacturers use the Oehler M83 with strain gauges attached to these production firearms. The M83 is somewhat more sophisticated than the M43 and the m83 is a “laboratory†instrument as Hot Core likes to rant about.

I am not sure inhowfar I should be happy about that. A strain gauge fítted barrel is certainly a BIG improvement over merely looking at a chronograph and trying to guess something out of your case head, your primer or your tea leaves. Still, I wonder why not proper pressure barrels are used in these cases, though I am afraid I can guess the answer.â€

As I stated above; the ammunition manufacturers also test their ammunition in factory rifles “after†they pressure test them. Many simply use the M83 as a cross check. Also many smaller ammunition companies that can not afford the expense of a laboratory and ballisticians use the M83 as their primary pressure testing equipment. As such the strain gauge is attached to factory firearm barrels or to custom barrels.

“The psi of all those cartridges was where the published information said it should be.


I would doubt this. The "published information" as printed in ammo catalogues, on cartridge boxes etc. is almost always given higher than the *actual* pressure as measured in a test barrel, for the very reason that you had lateron agreed with. Maybe you meant that the specific individual *lot data* that you received e.g. from Hornady were close to your own readings?â€

Yes, I was referring to the “published†(bad word on my part) information I received from Federal and Winchester. I thought I made that clear but obviously didn’t.

"Psi†as used with strain gauges, conformal transducers and piezoelectric transducers (several types, ) are calibrated in their respective computers to give the same value of “psiâ€.


Calibrated? How so? A fixed strain gauge in universal receiver or any other technical receptable might be calibrated via hydraulic pressure; but how would any gauge manufacturer be able to do this when he does not even know how and where there gauge will be mounted, how thick (in the given case) the barrel walls will be etc.? I still do not quite understand the assumption.â€

As I previously explained, the maker has an array of other instruments to which they “calibrate†new instruments. Let me ask you this; Is there stored a “standard psi†somewhere? Is there a “standard psi†that everyone in the industry has access to? Is it at Fort Knox? Is there one in Europe where all the CIP testers in the proof houses have access to? Just where is this “standard psi†and just how is it measured? Who, and with what, “calibrates†the calibrating machines, ammunition or whatever? When you buy a micrometer you assume it is “calibrated†but do you really know if what it says is .014†is really .014â€? Is the tachometer on your car calibrated before it is installed? Yes it is, but calibrated to what? How do you really know that 2100 RPM that the tachometer says is really the RPM the engine is cranking? What I do know is this; the industry goes by what pressures it deems are safe. The M43 gives pressure reading consistent with the industries pressure readings. Information I have is even the different ammunition manufactures pressure testing equipment does not agree on the pressure of the “reference ammunitionâ€. So who is right and who is wrong? We only measure things the best we can and use those measurements to stay within safe boundaries.

“quote:
Bottom line is I’ve tested factory and handloads of several different cartridges in several different rifles of the same cartridges and found the variations in pressures to be within expected between pressure barrels. A load that is safe in one rifle has proven safe in another. That is the same result as the factories expect when they sell their ammunition.

This is indeed as should be expected. Test barrels should be CIP minimum, and thus RL rifles will likely exhibit less pressure.â€

That is a fact. Again we are in agreement.

Thank you Carcano91 for this discourse and the pleasure to discuss this with you.

Larry Gibson

Mmmm. That was interesting! I can understand how a strain guage can be made quite reliable. It's all in the software! One question that has been on my mind for some time now. Recoil acceleration-time measurement as a means of deducing the pressure-time curve. One doesn't hear much on it. Is it do-able or even reliable? Would it be cheap enough for someone who works to a budget? Is it done?

quote:

Originally posted by 303Guy:
One question that has been on my mind for some time now. Recoil acceleration-time measurement as a means of deducing the pressure-time curve. One doesn't hear much on it. Is it do-able or even reliable? Would it be cheap enough for someone who works to a budget? Is it done?

Yes indeed. Dr. Geoffrey Kolbe from Border Barrels (UK) had such a pressure gauge (basically a gun-mounted accelerometer) patented in 2002. It was discussed several times here on the board, a couple of years ago - use the search function to find these postings.
But I also wonder why not much has been heard about it afterwards...?

Carcano

I think I am done with my repsonse now; thanks for your patience

quote:

Originally posted by Larry Gibson:
Carcano91
“Whew†is right! I shall try to cut to chaff here and respond to your answers (quoted). I will, for the most part, delete those where we are in agreement;

I have done the same before . This mutual practice - fruitful maybe in order to concentrate on learning, rather than on patting each other's back - can however give a misleading impression to the casual reader. I wonder whether I should have stressed more where Larry and I agree - for this was the case mostly, where I did not bother to "nod" expressedly.

quote:

Probably my bad here; you are correct that I refer only to those lots of Turkish ammunition that I have knowledge of. I have shot several other lots than those mentioned and they exhibited the same “sticky bolt†extraction. I did not however test them as I did with those lots mentioned. It is entirely possible that there are some over pressure lots out there.

Okay. Fine that this is clearified .

quote:

quote:

“Both. The conclusion only works in one direction, so one must distinguish:
- That a given load combination does not exhibit higher velocity than others (even than factory loads), does NOT infer that is safe; it might still have high pressure.
- On the other hand, a lot that is significantly faster out of the same gun with the same bullet and the same case will usually achieve (though not necessarily in every single case) this via higher pressure.
The two other exceptional factors are special bullet lubrication (molybden sulfide) and special (high-energy) powders from long barrels.â€

We agree, but I don’t think you quite explained it that way originally. I could be wrong but that’s not the way I understood your original explanation. However in the end here we are on the same page of the hymn book.

Nod.* I may have been too brief, too obtuse, or even (*gasp*) wrong in my initial explanation / wording. What I wrote above is hopefully my better assessment.

quote:

The instrument (sc. the Oehler M43 strain gauge system) is calibrated by the maker who has the full array of pressure measuring devices. That is his business, he sells the pressure measuring instruments to the ammunition makers, he has been in business a long time. No one, except a couple individuals on this forum, doubt his credentials or the accuracy of his instruments. The strain gauges measure the expansion of the steel. Barrel steel has known expansion properties. Measurements are taken of the outer diameter of the barrel where the gauge is attached and on the inside of the chamber where the gauge is attached. With the known properties the expansion properties are then calculated. This is done with proven engineering principles.

This explanation makes sense to me, thanks. I understand that the programmed equation will probably take into consideration the thickness both of the barrel and of the receiver, where the strain gauge is mounted. I did wonder a bit about the receivers that might not shaped tubular on the outside, but slightly tapered or swaying, but I do not know how rare these cases are. Also - and that is more important - many modern hunting rifles have the bolt lock directly into the barrel (barel extension), and these barrels is no longer strictly cylindrical at the chamber area. I believe this animadversion of Hotcore might deserve more attention than hitherto, don't you think so?

quote:

I have stored different lots of several cartridges to use as my own “reference ammunitionâ€. Testing this ammunition as the barrel wears will give a good indication of what to actually expect.

This sounds like a very sensible precaution indeed.

quote:

The published ammunition specifications are much closer to reality than they were in pre-chronograph days.

Agreed. This may be due to three factors (in no specific sequence of suggestive likelihood...):

- especially tight test barrels used for velocity readings
- especially long barrels (up to 72 cms were not unheard of in Europe)
- more honesty in advertising today.

Ah: the chronograph was already in full military use in the late 19th century. But I gather few civilian ammunition makers used the (very expensive) mechanical chronographs of the time, which were mostly a military and/or university affair. And radar measurement was not in use until post-WW II.

quote:

Also many smaller ammunition companies that can not afford the expense of a laboratory and ballisticians use the M83 as their primary pressure testing equipment. As such the strain gauge is attached to factory firearm barrels or to custom barrels.

Hm. A very dubious practice. VERY. Here in Europe, outsourced pressure measurements by the proof houses or by civilian institutions are cheap to come by, and there is not the slightest excuse not to use these, but to rely on a (sole) strain gauge and factory barrels instead.

quote:

quote:

"Calibrated? How so? A fixed strain gauge in universal receiver or any other technical receptable might be calibrated via hydraulic pressure; but how would any gauge manufacturer be able to do this when he does not even know how and where there gauge will be mounted, how thick (in the given case) the barrel walls will be etc.? I still do not quite understand the assumption.â€

As I previously explained, the maker has an array of other instruments to which they “calibrate†new instruments. [u]Let me ask you this:[/u] Is there stored a “standard psi†somewhere? Is there a “standard psi†that everyone in the industry has access to? Is it at Fort Knox? Is there one in Europe where all the CIP testers in the proof houses have access to? Just where is this “standard psi†and just how is it measured?

You are welcome to ask.
I was referring to *real* units, not to 18th century US practices, such as might be paces, bushels, stones, thumbs' widths, cigarette lengths, psi and the like. Real units are SI units. Only. And they are indeed bindingly defined and reproduceable. Welcome to the Modern Times.

quote:

Who, and with what, “calibrates†the calibrating machines, ammunition or whatever? When you buy a micrometer you assume it is “calibrated†but do you really know if what it says is .014†is really .014�

You may here indirectly refer to earlier disputes with Hotcore, but these disputes were not mine, so I will not honour them.

Yes, an Oehler M43 like any measurement instrument may be calibrated. A sensible and close way to do this might be to install the gauge (or rather: a master gauge) on a out-house pressure test barrel supervised by SAAMI or CIP.

This however is only one possible calibration method, maybe the one the would come closest to the mind of a shooter and reloader who is not necessarily a technician herself/himself, but it is not necessarily (maybe not even probably) the best or most accurate method, so I should like to suggest that my words are not construed as an endorsement of only such a calibration method, which would possibly be a rather uninformed concept.

I would suppose that industrial strain gauges, speaking in general, are calibrated via a predefined hydraulic pressure within a given pressure vessel to the outside of which the gauge is attached (or, alternatively: by squashing the gauging strip itself). The expansion of the test vessel can be very accurately measured by other means, and the relation of expansion to pressure can be calculated when knowing the material properties of the vessel, as you explained before. Such a calibration might even be superior to simply fixing the gauge to a pressure barrel of close, but changing tolerances, within which "reference" ammunition of close, but changing tolerences is fired.

Last line, if you allow me the purloining of your own words:
Thank you Larry Gibson, in return for this discourse and the pleasure to discuss this with you.

Carcano

Carcano91

Looks like we are pretty much in agreement as you mention. Just a couple comments though.

"This explanation makes sense to me, thanks. I understand that the programmed equation will probably take into consideration the thickness both of the barrel and of the receiver, where the strain gauge is mounted. I did wonder a bit about the receivers that might not shaped tubular on the outside, but slightly tapered or swaying, but I do not know how rare these cases are. Also - and that is more important - many modern hunting rifles have the bolt lock directly into the barrel (barel extension), and these barrels is no longer strictly cylindrical at the chamber area. I believe this animadversion of Hotcore might deserve more attention than hitherto, don't you think so?"

Not sure you understand here as you mention the reciever; the strain gauges are not attached to the recievers. They are only attached to the barrels directly over the chamber. This precludes the use of strain gauges on some action/cartridge combinations where the chamber does not extend past the reciever. In many instances there is a slight taper either on the inside of the chamber or on the outside of the barrel over the chamber. However if we note that the width of the gauge is quite small (.18" to be exact) then we may consider the effect of that taper to be within the normal fluctuation of measurement. Bear in mind, not withstanding the "animadversion of Hotcore", that normal shot to shot variations of psi are expected to be +/- 2-4K psi. Most factory psi's are stated in multiples of 50 with multiples of 100 being the lowest seen. PSI is not measured down to that one psi. Thus any variation caused by any taper is no doubt so miniscule that it isn't noted because of the normal psi fluctuation. This may even be more so as when comparing psi measurements from two different systems.

"Hm. A very dubious practice. VERY. Here in Europe, outsourced pressure measurements by the proof houses or by civilian institutions are cheap to come by, and there is not the slightest excuse not to use these, but rely on a (sole) strain gauge and factory barrels instead."

Dubious perhaps but considering your previous comments concerning the over use of test barrels at said test houses may mean one system may not be any more reliable than the other, eh?

"You are welcome to ask.
I was referring to *real* units, not to medieval US practices, such as might be paces, bushels, stones, thumbs' widths, cigarette lengths, psi and the like. Real units are SI units. Only. And they are indeed bindingly defined and reproduceable. Welcome to the Modern Times."

Ah, so continental and cavelier! And there I thought "medieval, paces, bushels, stones, thumbs' widths, cigarette lengths" were of European origin! Of course "psi" may indeed be an American or British designation but it does work. LOLs and always a pleasure discussing topics with you, I look forward to more discussions in the future.

Larry Gibson

Man, You Guys are writing books!!! Turk ammo has always been hot and suspect. I just bought a case (1400) of 1949 that I can't wait to shoot out of a Yugo 24/47. $100.00. I also bought a case of 1971 Brit .303 (600) for $60.00. Both are sealed and I am happy to find them. JP
P.S. I also found 1000 rounds of 7.5 french, Cost: $185.00 that included a M1936 Mas that is all matching and perfect!

quote:

I also bought a case of 1971 Brit .303

If it is to be used in a Mk III SMLE, just make sure it is not machine gun ammo. The stuff I used was marked R2M2. I can't help wondering whether that Turk ammo is machine gun ammo. (Not sure why it would be different for 8mm Mauser unless the rifle ammo was low pressure. Machine gun ammo would be more plentiful for surplus, would it not?)

quote:

Originally posted by Jpat:
I also found 1000 rounds of 7.5 french, Cost: $185.00 that included a M1936 Mas that is all matching and perfect!

Sincere congratulations! That is what I would call a "gloat post".

Carcano

quote:

Originally posted by 303Guy:

quote:

I also bought a case of 1971 Brit .303

If it is to be used in a Mk III SMLE, just make sure it is not machine gun ammo. The stuff I used was marked R2M2. I can't help wondering whether that Turk ammo is machine gun ammo. (Not sure why it would be different for 8mm Mauser unless the rifle ammo was low pressure. Machine gun ammo would be more plentiful for surplus, would it not?)

The Turk stuff I used all came out of sealed cans with original markings that match the head stamps and was in 5 shot strippers in bandoliers. Not hardly "machinegun ammuntion". The German "machinegun ammuntion" was a lighter bullet at higher velocity not higher pressure as is commonly believed. With German SS and JS ammo also running at 58-60K psi a "higher pressure" load would have been disasterous to the machine guns. Actual data reveals lighter bullets at higher velocity than SS ammuntion, not higher pressure. The JS (actually a misprint as it really is IS)still is the lightes bullets and the fastest. The JS ammo just didn't carry well and didn't have the API and tracer capability.

The Japenese did in fact have a higher pressure machinegun load. I am not sure about the .303, would have to research that a bit more or perhaps you can provide documented information?

Larry Gibson

I haven't been able to find any documented information, only comments relating to it. I chrono'd the stuff I used and found the velocity to be considerably higher than rifle ammo. I do not recall the actual figures. ( I think it was 2560 fps). The bullet was 175gr - hardly different from 174gr. The propellant was ribbed, hollow cordite packed real tight. The bullet was aluminium tipped (internally). If I recall, there was no cardboard wad. Only the head-stamp 'R2M2' was different externally.

I did not know about the German machine gun ammo. I knew about the two bullet weights but thought they might have been 'earlier' and 'later' developments.

I read somewhere that the Japanese machine gun ammo was rimmed or semi-rimmed and that it was based on the 303 case. (I also read that the 7.7 Jap had the 303 round as a 'parent' case, but it was only inspired by the 303 round).

quote:

Originally posted by 303Guy:
I did not know about the German machine gun ammo.

That is because it usually did not exist. Okay, it is more complex:

- In the Great War, the sS lead core bullet (12,7-12,8 grams) was developed to give some extra range to machineguns, as compared to the lighter and older S lead core bullet (10,0 grams). The sS bullet then soon superseded the S bullet altogether in rifles, carbines and machineguns, until in World War II, the lighter SmE (11,5-11,6 grams) iron core bullet became regular issue for rifles and machineguns alike. None of them are much "hotter" than the other pressurewise, and the old S bullet load from 1904/05 was the fastest of all.

- There did admittedly exist a special German aircraft machinegun load in WW II, designated by a green bullet tip ring (v-Munition), loaded as SmK, PmK and B-Patrone (all are lighter bullets!). Apart from the special bullets, its main features were more reliable function also in extreme cold (high up in the sky), and slightly different burn characteristics of the employed tubular powder (the other rounds used flake powder). The velocity of all v-Patronen is stated to be higher in the military manual (understandable with the lighter bullets that were loaded), but the pressure was not noteworthily different.

Carcano

quote:

Originally posted by 303Guy:
I haven't been able to find any documented information, only comments relating to it. I chrono'd the stuff I used and found the velocity to be considerably higher than rifle ammo. I do not recall the actual figures. ( I think it was 2560 fps). The bullet was 175gr - hardly different from 174gr. The propellant was ribbed, hollow cordite packed real tight. The bullet was aluminium tipped (internally). If I recall, there was no cardboard wad. Only the head-stamp 'R2M2' was different externally.

South African. Pretoria Metal Pressings. R1M1 and R1M2 are documented in Italian literature (Riccardo Corsi).

See also Dave Cushman's site for a comparable example (R1M3):
http://www.dave-cushman.net/shot/303headstamps.html

Carcano

Quite some time back, in fact, years I read a publication by HP White Labs as I recall that basically agreed with what LG is saying..

I have no dog in this fight but it was an interesting and intelligent conversation, until the ya ya started..

Thanks for that carcano91. Very intersting. Thanks for the head stamp link. I should have mentioned I was living in South Africa at the time. The R1M1 and R1M2 head stamp appeared on all military calibers. So, for now, the R2M2 machine gun 303 round remains a speculation. I have a friend in RSA whom I could ask to research for me.

Was the 303 look-alike the standard Japanese machine gun?

My appologies, p dog shooter, for deviating off the 8x57 topic. (It is slightly related. ) I must say, your thread has raised some interesting facts on the 8x57.

Here's what I have found on the 'net;

from Wikipedia

quote:

"Cartridges with the Roman numeral VIII on the headstamp are the Mark 8 round, specifically designed for use in Vickers machine guns."

quote:

"Japan produced a number of machine guns that were direct copies of Lewis and Vickers machine guns (Type 92 machine gun and Type 97 machine gun[citation needed] respectively), these were primarily used in Navy aircraft. The ammunition used is of the same specification as .303 British."

from www.dave-cushman.net/shot/303hist.html

quote:

"In 1938 the .303 Mark VIIIZ round was approved to obtain greater effective range from the Vickers Medium Machine Gun. This round had a nitro-cellulose powder charge with a 175 grain boat tailed, streamlined, steel jacketed bullet having a muzzle velocity of 2550 fps. Chamber pressure however, was higher at 20 - 21 tons per sq" compared to the 19.5 tons per sq" of the Mark VII round."

from http://enfieldrifles.profusehost.net/gh2.htm

quote:

"The only other significant 303 cartridge developed was the MkVIII round, which was intended for use in the Vickers Machine Gun. This round had a nitro-cellulose powder charge with a 175 grain boat tailed, steel jacketed bullet having a muzzle velocity of 2550 fps."


"Cautionary Notes

Caution should be exercised when considering the use of the MkVIII round though, especially in older Long Lee’s or SMLE’s. According to Labbett & Mead's ".303 Inch" ballistics for the MkVIII it is listed as 20-21 tons/sq versus 19.5 for the MkVII with a muzzle velocity of over 2500fps as opposed to the 2440fps of the MkVII. At 2240lb/ton, this means pressures of up to 47,000psi, which is chasing at the heels of, if not breaching, current published safe pressures for the Lee action. I must thank Dr. Justin Moretti for bringing this potential hazard to my attention."

So, that would be myth confirmed!
Note that two sources state the velocity of the MkVIII as being 2550 fps. This is what I recall measureing. And I fired this stuff - nearly 500 rounds of it - through my 1902 LMLE! (Well, put a case of 1000 rounds of ammo on the ground in from of me and I'm the only one with a 303, what would I do? ) It did damage my gun slightly. There was a measurable increase in headspace and the rifling was visibly not as sharp for the first third as it once was but there were no detrimental effects. The rifle is still in spec and still shoots just fine.

Well to clarify, .303 is VII case marked. 8x57 is on strippers and in bandoliers.