quote:

if you want the ONLY Pressure Indication Method which will ALWAYS keep you SAFE, simply follow what the Link says.

Simply not true;

Read my last post above concerning the .280 Remington. There was no indication of high pressure either in the first test or during the second test. A blade micrometer was being used and three of us were taking measurements on the same cases during the second test. CHE did not prevent the destruction of the first action and would not daoubt have not prevented the destruction of the second action. The use of the chronograph did however tell us we were way high on pressure with a velocity of 3012 fps with a 168 MK in a .280 Remington.

Larry Gibson

RE; Hot Core's change of opinion.......

Well folks I am somewhat flabbergasted to say the least. Seems Hot Core won't be needing to use CHE anymore as he'll only stick with factory or loads out of manuals. What can we say.....

He post today on the Small Calibers Forum in the thread on reduced loads of BlueDot;

"Since Mr. Ben's post from Alliant, I no longer support any Load that is not found in a Manual. It is a Liability issue for sure. And if the big dollar companies don't want to deal with it, I for sure don't want to either.

There are all kinds of excellent Reduced Loads in the Powder and Bullet manufacturers Manuals that have been Tested on their $$$Million$$$ equipment. I strongly encourage EVERYONE to begin using Factory Tested Loads and forget Blue Dot as a Reduced Rifle Load."

Larry Gibson

quote:

Originally posted by Larry Gibson:
RE; Hot Core's change of opinion.......

Well folks I am somewhat flabbergasted to say the least. Seems Hot Core won't be needing to use CHE anymore as he'll only stick with factory or loads out of manuals. What can we say.....

Hey Larry, Where did you see that I said I won't be using CHE/PRE?

Your reading comprehension is really in bad shape.

Hot Core

Logic, which seems to have passed you by. If you do as you've now said, i.e. use only factory ammo or stay within loads listed in manuals, CHE is useless because you will not be into a bressure range that will expand the case head or the belt. You will not need to use PRE with lessor pressured cartridges because with factory ammo it IS factory pressures and with reloads the manuals say they do not exceed factory (SAAMI) pressures for cartridges fired in the original firearms made for them. Not to hard to figure out.

As to your last sentence; my reading comprehension is fine. It is you who have lost almost all credibility here by your own statemets, admissions and juvenile personal accusations. Another juvenile accusation here does you no credit.

Larry Gibson

quote:

Originally posted by Hot Core:

quote:

Originally posted by Larry Gibson:
RE; Hot Core's change of opinion.......

Well folks I am somewhat flabbergasted to say the least. Seems Hot Core won't be needing to use CHE anymore as he'll only stick with factory or loads out of manuals. What can we say.....

Hey Larry, Where did you see that I said I won't be using CHE/PRE?

Your reading comprehension is really in bad shape.

I'm not riled, hotcore. (notice I didn't substitute blowhard, braggart or know-it-all for your username). You keep harping about keeping beginners safe, yet I don't recall one admitted newby asking this forum the proper way to measure CHE, or where to buy the tool to do so.

Instead of your vendetta against strain gauges, why not rally for more blade mike availability?

The second thing a reloader learns, after 'work up cautiously' is to be aware of signs of high pressure. Agreed? Flattened or cratered primers is the #1 way we judge high pressure. CHE is another way.

With all the gadgets and gizmos available to us reloaders, I'm just curious why a basic hand-operated tool to measure pressure like the Starrett blade mike is a special order item? (For further information, availability, and price, call the Special Order Department at 978-249-3551 x410.)

It has come to my mind, lo these many years that I've been hearing you thump your chest of the virtues of CHE/PRE, that you do so in such a voracious manner that you must be getting royalties from some unknown entity to do so. You're akin to a rabid dog in that respect. Do you really enlighten many souls here on AR? If so, what is the tally so far?

Just so other folks know exactly what side I'm on, I'm one of hotcore's 'fools' who invested in, not only a Oehler M35 chronograph, but one of Dr. Oehler's M43's, too. Even the accoustic target!!!

BTW, if anyone wonders why Dr. Oehler doesn't chime in with his educated prospective, it's probably because hot- fucking -core single-handedly brow beat him with his strain gauge vendetta. Coni Brooks of Barnes and Craig Boddington are also victims of the same kind of tactics. Only Alaska guide Phil Shoemaker has a thick enough hide. He's still around to give his experience.

I'd trade hotcore in a new york minute for Dr. Oehler!

quote:

Originally posted by Larry Gibson:
Hot Core

Logic, which seems to have passed you by. If you do as you've now said, i.e. use only factory ammo or stay within loads listed in manuals, CHE is useless because you will not be into a bressure range that will expand the case head or the belt. You will not need to use PRE with lessor pressured cartridges because with factory ammo it IS factory pressures and with reloads the manuals say they do not exceed factory (SAAMI) pressures for cartridges fired in the original firearms made for them. Not to hard to figure out....

No Larry, You are wrong again. Every Firearm is a separate process. What might be OK in one firearm is not necessarily OK in another firearm. If people want to remain SAFE, they still need to use CHE & PRE.

No wonder you have trouble with all this if you don't even understand the basics.

Hot core,
How can you keep it up?
The two guys above with poor manners are never going to learn while they are so vehement.

They need to find out about pressure signs on their own.

If the brass is the weak link and they get nasty at the suggestion of reading the brass for developing loads, they have major personal issues.

How do you stay so optimistic that you can help them?

I would just let them stay at the level they are on, some SAAMI driven strain gauge boondoggle.

They may never get past that point.
Are you going to keep trying forever?

Hey fuz, Had no idea you got sucked in to buying a worthless HSGS. That does explain your "mad".

No, Flattened Primers are not measurable as I said above. Using CHE & PRE, the prudent Reloader does not have to get to that level.

Don't know how many folks I've helped. If I saved one from wasting money on a HSGS, it was worth it.

I sure don't remember posting in a thread with Mrs. Brooks. Do you have a Link to it or remember which Board it was on?

I like Boddington, but if he though the could just come strolling into the Board with folks kissing his feet, he was very mistaken. If he couldn't take folks disagreeing with him(which I did not do), then he is better off not being here at all.

I also do not remember speaking with Mr. Shoemaker. I believe he posts as "458win", but I really don't remember any discussions are arguments between us. Do you have a link for that too?

Also respect Dr. Oehler and if you follow the thread where I did get to discuss HSGSs with him, we agreed far more than we disagreed. Dr. Oehler even said he prefered the term "Haphazard" instead of "Home" in HSGS and I have no problem agreeing with him about that either. He answered all the legitimate questions about his product that I asked. And yes indeed, they were a bit tough, because I know how totally worthless a non-calibrated, guessed at dimension, fudge factored HSGS happens to be.

I do understand now why you are mad - tough cookies.

Hey tnekkcc, Try as I might, it does seem the "truth" is very difficult for some folks to realize. I still try to be my "Amiable" old self.

Fuz has me concerned about Mrs. Brooks though. Surely she is smart enough not to champion worthless HSGSs. I hope he has a link because I would like to see what he is talking about.

I don't really believe I (actually we) are "helping" Larry and Fuz. They are convinced they did not get PT dentoned, and I really see it as sad. I might not even be able to sleep tonight.
-----

Perhaps you could recommend a site to them where everyone agrees about everything, no one ever disagrees and it is just a warm and "fuzzy"(pun intended ) place.

P.S. Thanks for hanging in there with me.

/

Alf

Once again Hot Core fails to answer any question directly just a lot of meaningless tangents and personal inuendoes. He has been asked by myself and numerous others for some time now to give his back ground, education and experience to back up his profound, to say the least, claims. He continuously fails to provide any meaningful information here, on other forums or anywhere that any of us can find. He really reminds of a poster on forums some time back called "Gun Kid".

An how about tnekkcc, mr. load 'em up until they blow, who gets knifed in the back by Hot Core with;

"Since Mr. Ben's post from Alliant, I no longer support any Load that is not found in a Manual. It is a Liability issue for sure. And if the big dollar companies don't want to deal with it, I for sure don't want to either. There are all kinds of excellent Reduced Loads in the Powder and Bullet manufacturers Manuals that have been Tested on their $$$Million$$$ equipment. I strongly encourage EVERYONE to begin using Factory Tested Loads and forget Blue Dot as a Reduced Rifle Load."

And tnekkcc still thinks Hot Core hasn't sold him down the river! This is what we're trying to reason with? Maybe we are "dumber than Denton" for continuing to try. I don't know who "Denton" is but I'd bet he's not dumb. I know who I'll put my money on with that issue.

Anyways how about you and I and all the other intelligent reloaders who use the tools available to us (ah yes, that can include CHE and PRE but not to the exclusion of other valuable tools) to work up safe loads, even safe maximum loads, continue to advise other reloaders in what those tools are and how to use them appropriately.

I, myself, will continue to call BS on Hot Core and Tnekkcc with regards to this issue.

Larry Gibson

Alf,

quote:

The method calls for the plotting of average velocity on a graph against charge mass as shown in the Somchem manual ie V/C value. The relationship between chamber pressure and muzzle energy is valid and based on this CIP will assign proof if a load conforms to the parameters of the relationship.

I am not sure the SABS proof lab in Pretoria does it this way. I sent them two wildcats to proof because, without the proof certificate, the owners could not apply for a license. Initially they did not want to proof the rifles but I insisted that the new act requires proofing before an application can be considered. How it is done was not my problem. In both cases I sent the barreled action and three loaded rounds and, in due course, received a proof certificate for the rifles.

Has anyone ever wondered why none of the load manuals has ever listed case head expansion numbers to pertain to the tested cartridge's pressure? Not Lyman, Speer, Sierra, Nosler, Hornady, Barnes, hell, you name it. None has ever included a number that the hobbyist can measure with his special order Starrett blade micrometer, not commonly available from normal reloading suppliers. Why is that?

If measuring CHE is so simple even a caveman can do it, why don't the reloading manuals list their findings in increments of .0001" so that we may make comparisons?

God, I hope it's not some sort of government or lawyer mandated conspiracy! If it is, it's been going on since before I started reloading ammo in '71.

quote:

Originally posted by onefunzr2:
Has anyone ever wondered why none of the load manuals has ever listed case head expansion numbers to pertain to the tested cartridge's pressure? Not Lyman, Speer, Sierra, Nosler, Hornady, Barnes, hell, you name it. None has ever included a number that the hobbyist can measure with his special order Starrett blade micrometer, not commonly available from normal reloading suppliers. Why is that?

If measuring CHE is so simple even a caveman can do it, why don't the reloading manuals list their findings in increments of .0001" so that we may make comparisons?...

Hey Funz, Actually the older Manuals as well as Books by Waters, Hagel and Sitton explain that. The information about how to do it is in the Link.

However, CHE in one firearm does not compare to CHE from anyone else's firearm. It will vary from firearm to firearm, just as all knowledgeable Reloaders understand that Loads will vary from firearm to firearm.

It is because of all the variabilities in both the Load(Case, Primer, Powder and Bullet) plus variances in the Bore and Chamber dimensions. Just that simple, nothing tricky about it.

So, a comparison of CHE measurements between firearms is not meaningful. It is only meaningful about how the Pressure in the specific firearm with the specific Load Indicates Pressure on the specific Lot of Cases.

All anyone has to do is try it and it is easy enough for "nearly anyone" to understand - if they follow the Instructions.

Everything you point out is also applicable to either the CUP or PSI pressure amounts printed in load manuals. But they still include them. Why is that?

Shotshell manufacturers have started to drop the 'dram equivalent' of blackpowder markings on their products. They now list FPS and pressure. I'm guessing because 'dram equivalent' has become outmoded and obsolete. Probably the same as your PRE\CHE...old-fashioned, outmoded, obsolete, hard to use, not particularly accurate and with no modern reference equivalent. Only used by ancient geezers who cannot move forward, or actually relish living in the past. Which is it?

Slide rules have given way to handheld calculators. So PRE\CHE have been superseded by the strain gauge. Get used to it or keep rambling on like a feeble-minded fool. All under the guise of keeping 'beginners' out of trouble. What a joke you are, sir.

quote:

However, CHE in one firearm does not compare to CHE from anyone else's firearm. It will vary from firearm to firearm, just as all knowledgeable Reloaders understand that Loads will vary from firearm to firearm.

It is because of all the variabilities in both the Load(Case, Primer, Powder and Bullet) plus variances in the Bore and Chamber dimensions. Just that simple, nothing tricky about it.

So, a comparison of CHE measurements between firearms is not meaningful. It is only meaningful about how the Pressure in the specific firearm with the specific Load Indicates Pressure on the specific Lot of Cases.

All anyone has to do is try it and it is easy enough for "nearly anyone" to understand - if they follow the Instructions.

Hot Core advises us of the above; so I have to ask: Since CHE and a strain guage both measure second hand information how is the measurement of "Pressure in the specific firearm with the specific Load" more reliable with CHE? The answer is; it is not.

CHE is actually less reliable as it only tells you when you have exceded the pressure limits of the case and that can be a dangerous thing to do. A strain guage measurement tells you well before you have exceded acceptable pressures that pressures are getting high as you work up a load. The use of the strain guage tells us when we are in the right pressure range. (Hot Core; there is no such thing as "calibration ammo" so don't bring that up again). One may and should use several different factory loads to establish a reference for pressure in that firearm. Then if one wants to proceed with higher pressure than factory ammo at least with a strain guage measurement you will see that progressian. With CHE you will only know the pressures are too high when the case fails (that is, after all, exactly what a measurement of CHE is - case failure) whether you are initially working up a load or being bold and going beyond factory velocities.

Now back to the original part of this thread. With the use of a chronograph one can see the consistancy of the load as development progresses. Using appropriate and comparable componants and comparing normal pressure signs with velocities to factory or reloading manual velocities as loads are increased gives a viable indication that pressures are within acceptable limits.

Neither the use of CHE, PRE or a chronograph gives a pressure measurement. The M43 with the strain guage does. PRE and the use of a chronograph can tell you when you when you are still within acceptable pressures but CHE only tells you that you have exceded acceptable pressures. If using just CHE or PRE you do not know if the load is actually under, at or exceding factory ballistics. All you know is you have met (PRE) or exceded acceptable pressurs (CHE) for that load. However, if you are using a chronograph for velocities why not use the information provided and avoid exceding acceptable pressures by using CHE in the first place. That is what knowledgeable reloaders do.

Larry Gibson

[/

quote:

Originally posted by onefunzr2:
Everything you point out is also applicable to either the CUP or PSI pressure amounts printed in load manuals. But they still include them. Why is that?

It does not seem that you are really interested in hearing honest answers from someone who knows.

quote:

Shotshell manufacturers have started to drop the 'dram equivalent' of blackpowder markings on their products. They now list FPS and pressure. I'm guessing because 'dram equivalent' has become outmoded and obsolete. Probably the same as your PRE\CHE...old-fashioned, outmoded, obsolete, hard to use, not particularly accurate and with no modern reference equivalent. Only used by ancient geezers who cannot move forward, or actually relish living in the past. Which is it?

Taking shots at "old folks" and Methods which are better than the new fangled things does not speak well for your intelligence.

quote:

Slide rules have given way to handheld calculators. So PRE\CHE have been superseded by the strain gauge. Get used to it or keep rambling on like a feeble-minded fool. All under the guise of keeping 'beginners' out of trouble. What a joke you are, sir.

As a matter of fact, I still have a Dual Log Pickett that my Calculator sits next to. Always there to remind me of what it used to be like. In that situation(Slide Rules vs. Calculators) I'd also go with the Calculator - but I can use the Slide Rule if need be - maybe, it has been a long time ago.
-----

A non-calibrated, guessed at dimension, fudge factored HSGS = Reloaders Pyrite(aka Fool's Gold)

quote:

Originally posted by Larry Gibson:
...Since CHE and a strain guage both measure second hand information how is the measurement of "Pressure in the specific firearm with the specific Load" more reliable with CHE?...

No reason to read farther, cause larry has got it ALL WRONG in his first sentence.

Taking Pressure Indications from the Case = First Hand information.

Taking (Bogus) Pressure Indications from a Strain Gauge = Third Hand information.
-----

The farther the data is removed in segments or steps from the Test, the value becomes less accurate. Simple Engineering Laws which I feel sure a couple of young folks will have trouble understanding.

quote:

Originally posted by Hot Core:

quote:

Originally posted by Larry Gibson:
...Since CHE and a strain guage both measure second hand information how is the measurement of "Pressure in the specific firearm with the specific Load" more reliable with CHE?...

No reason to read farther, cause larry has got it ALL WRONG in his first sentence.

Taking Pressure Indications from the Case = First Hand information.

Taking (Bogus) Pressure Indications from a Strain Gauge = Third Hand information.
-----

The farther the data is removed in segments or steps from the Test, the value becomes less accurate. Simple Engineering Laws which I feel sure a couple of young folks will have trouble understanding.

Just the sort of response we've come to expect from Hot Core.

CHE measures what pressure does, not what it is. Strain guages measure what pressure does, not what it is. Same thing, both second hand. Any ballistician will tell you that in order to measure the actual pressure a device would have to be in inside the case. But then the integrity of the case would be violated and "estimates" of how much psi would have to be used for as a correction factor. Using that correction factor (an estimate) would put us right back where Hot Core wants us; using his method (CHE) only. I suppose he would challange us to get some sort of "calibration estimate" from an "estimate" regulating agency to calibrate such a device. He apparently doesn't realise that CHE is only an "estimate" also.

The problem (reiterated here again) is that CHE is only valid if we excede acceptable pressures and cause the case to fail. It is, in fact, only an "estimate" that only tells us we have made the case fail. CHE does not tell us by how much we have made the case fail or how much we have exceded acceptable pressures.

Perhaps Hot Core could convince the ammunition manufacturers that they should provide the case head expansion reloaders can expect to get with loads of 70, 80 and 90,000 psi in say 500 psi increments for the various lots of different cartridge cases available. I can see them doing that, can't all of you? However, then we would have to have all of our micrometers (.00001 capable of course) "calibrated". Gee whiz Hot Core, with you being the "industry expert" on CHE you ought to get that done without any problems don't you think?

Ok, enough of that, back to serious; with a strain guage, transducer and even the copper crusher method of measuring cartridge pressures we can observe the rise in pressure when developing loads PRIOR TO exceding acceptable pressure limits by causing the case to fail. Thus there is no need to excede those acceptable pressures in any cartridge, low pressure or high when using a strain guage, transducer or copper crusher pressure measuring system. Also, through the correct correlation of inforation a chronograph tells you and applying that information with the other standard pressure indicators there is no need to excede acceptable pressures either. The use of transducers and the copper crusher method are pretty much industry used (the copper crusher is being phased out as it only tells "peak pressure" in favor of transducers which give a time/pressure curve) due to the cost. The use of chronographs has become affordable, easy to use and an accepted tool for reloaders to use. It can and is being used more and more to keep reloaders from exceding pressures. Of course the use of strain guage pressure measuring devices such as the Oehler M43 will no doubt become more in use by the more dedicated reloaders.

Hot Core apparently, with all of his self claimed experience (unknown what that may be as he wn't ell us), apparently can not comprehend that developing loads is better and more safely served by using a chronograph or more modern and accepted pressure measuring methods than CHE. But he has made his stand with CHE. Perhaps he is standing where the World is flat. So be it.

Larry Gibson

After reading (some) of this, I think the answer is to get a more powerful cartridge than you need and use some starting loads from a few good manuals. Sorta turn a 30-06 into a 308 Win.

quote:

Originally posted by JAL:
After reading (some) of this, I think the answer is to get a more powerful cartridge than you need and use some starting loads from a few good manuals. Sorta turn a 30-06 into a 308 Win.

JAL

It's quite easy to have an '06 be an '06. The problem is when you load it up to case head failure, i.e. CHE, you are trying to make it a 300 Winchester Magnum.

On the contrary; (e.g.) load the '06 with a medium to medium/slow burning powder (3031, 4895, 4320, 4064, Varget, 748, H414, etc) and a 150 gr bullet. Work up the load using a chronograph until you find a accurate load in the 2875-2950 fps range (22-24" barrel). I bet you won't have any pressure problems. You won't need a blade micrometer of .0001capability because there won't be any case head expansion (CHE) to measure as you will not have exceded acceptable pressures for the '06.

Yup, an '06 can be an '06 and the .308 can be a .308, both safely.

Larry Gibson

Sure Larry, but I don't want a chronograph.
The ones I've borrowed either told me what I expected (from the reloading manuals who probably used them), to telling me the velosity was low, (due to short barrels).

Like, I'd hate to try to get Winchesters published velosity of their 150gr 30-30 loads in my 20" carbine.

Yep sometimes my ignorance even amazes ME.
But an extra margin of error is not to be sneezed at.

JAL

Well not wanting a chronograph yourself is ok but I'm sure you have a buddy with one. There is sufficient information in most loading manuals that advise what velocity might be lost with your 20" barreled '06 (I have one too). What I'd do is pick upa box of Winchester or Remington PPs or CoreLokts of the weight bullet I wanted to reload for. Load up your test loads and go to the range with your buddy with the chronograph. Five rounds of the factory load will give you a good average velocity of that ammo in your rifle. Then test your loads. Stop shooting when the velocity is equal or near the velocity and you've not gotten any other signs of pressure. Note that the chronograph will tell you when the load begins to uniformly ignite by the smaller ES/SD combination. Pressure will be acceptable for your '06. If accuracy was acceptable you've got a load.

If not change to a different make of bullet with equal weight or try another appropriate powder. Some will get excited about bearing length changing pressure, etc. That it does but the factory load has about as long a bearing surface as any equal bullet from the bullet makers. A bullet with a shorter bearing surface like a SPBT will give lessor pressure.

Larry Gibson

quote:

Originally posted by 303Guy:
Delloro
Reading primers is my main pressure 'guessing' system. My hornet produces a little 'crater' ring like the first case in tnekkcc's photo but without the flattening at the edge of the primer. The firing pin indent is not that deep to start with. I do not get case head separation or even case length growth (if I do I back off). How would you 'read' that if I may ask? I am using Federal 205 primers.

FP diameter too small or FP hole too big or FP too short.

Thanks for that delloro. Maybe that is where I need to look to sort out my apparent inconsitant combustion problem. The firing pin indent is off-centre!

An off center firing pin strike can be caused by different things.
1. Oversize chamber, especially in the rear case body area and which is exagerated by full length sizing or
2. a misaligned (to the bore axis) firing pin and/or bolt.

Take six rounds and draw a line down the side of the case from the neck to the base with a felt tip marker. For every shot fired, load the cartridge with the line facing up. Fire three with the rifle held normally. See if there is a relationship to the firing pin indent and the line on the case. (Indent always at 4 o' clock or 9 o' clock or whatever.) If the indent is always at the same point relative to the line, the bolt/firing pin is misaligned except if the strike is always at 12 o'clock. Then it could be an oversize chamber and this you check by firing the rifle upside down, on it's left side and on it's right side. If the strike moves around, relative to the line, the case is undersize for the chamber. Either way a trip to a gunsmith and some $$ is the cure.

quote:

posted by larry:
...with a strain guage, transducer and even the copper crusher method of measuring cartridge pressures we can observe the rise in pressure when developing loads PRIOR TO exceding acceptable pressure limits by causing the case to fail.

quote:

The problem is when you load it up to case head failure, i.e. CHE, you are trying to make it a 300 Winchester Magnum.

The more larry posts, the funnier it gets.

quote:

CIP as a measuring standard is a matter of law (unlike SAAMI) and it's methodology or validation of methodology is upheld as a legal entity.

Could we call non conformists outlaws?



Warrior

/

/

Old hotcore once again proves the axiom: If you can't impress 'em with knowledge, dazzle 'em with your bullshit.

He has tucked his tail between his legs and run back into his hole waiting to emerge in a new thread to spew his foul rhetoric. Typical.

quote:

Originally posted by onefunzr2:
Old hotcore once again proves the axiom: If you can't impress 'em with knowledge, dazzle 'em with your bullshit.

He has tucked his tail between his legs and run back into his hole waiting to emerge in a new thread to spew his foul rhetoric. Typical.

Yes, and that is unfortunate as Hot Core did have some relevant comments on other topics. What is unfortunate is he most often lets his rhetoric get in the way of any inciteful information and knowledge he has.

As Alf points out;

"From the Reloading manual of the NRA 1981.
page 131 middle of the page:

Measuring case base diameter as a method of predicting pressure has at least 30% error based on the relationship between inconsistancies in brass hardness and deformation when subjected to pressure."

CHE has been dicredited for a long time. Later reports indicate that the 30% error reported by the NRA may be somewhat conservative.

Larry Gibson

quote:

Originally posted by Larry Gibson:
...Measuring case base diameter as a method of predicting pressure has at least 30% error based on the relationship between inconsistancies in brass hardness and deformation when subjected to pressure."

CHE has been dicredited for a long time. Later reports indicate that the 30% error reported by the NRA may be somewhat conservative.

quote:

Originally posted by delloro:

FP diameter too small or FP hole too big or FP too short.

Or fireing pin spring too weak.

quote:

...2. a misaligned (to the bore axis) firing pin and/or bolt.

* * *

Either way a trip to a gunsmith and some $$ is the cure.

the misaligned FP is an easy fix. "accurizing the factory rifle" explains how.

Thanks for that Gerard, JAL & delloro. I was wondering about the weak firing pin spring, but the misalignment and that slight cratering makes me think I have all three! I know my chamber is a bit large, but I do not resize. I will do the test you suggest Gerard, thanks. Would this all cause erratic ignition, or should I be looking at my rifle's barrel or my re-loads?

quote:

Originally posted by ALF:
From the Reloading manual of the NRA 1981.
page 131 middle of the page:

Measuring case base diameter as a method of predicting pressure has at least 30% error based on the relationship between inconsistancies in brass hardness and deformation when subjected to pressure.

Warrior:

If your country is a member of CIP and you commercially make arms and or munitions and you do not conform to the provisions you are a outlaw !

South Africa is not a member country BTW though they do apply the provisions of CIP

AlF, you are great guy and we appreciate your hard work on intelligent and informative posts, but you blew that transcription of Davis:

quote:

These hardness limits correspond to the yield strengths of roughly 70,000 to 90,000 psi. Since the chamber pressure at which a cartridge case head undergoes permanent deformation is proportional (though not equal) to the yield strength of the material, it is clear that some cartridge cases might be deformed at pressures as much as 30 per cent lower than that required to cause permanent deformation of other case heads. I is obvious, therefor, that chamber-pressure comparisons inferred from such signs as expansion of the case heads might be in error by 30 per cent of more. This kind of error is incomparably greater than the error in pressure measurements introduced by differences in the hardness among copper crushers. Indeed, if chamber pressure could be determined with satisfactory accuracy be so simple a process as measuring the diameters of fired cases, the cost-conscious manufactures of ammunition would long ago have abandoned the construction and use the of expensive pressure barrels and copper crusher or electron transducers.

The author, Davis, is great guy. I have seen him on the same cable TV show that shows my father's gun designs fighting in Viet Nam, "The Story of the Gun".

But Davis has stumbled on science and engineering here. Here at AR we had someone of higher technology on this exact topic, and before he left, he did Von Misses calculations [something Davis would have never attempted back in his prime] of PRE changes vs hardness of the brass [69 ksi to 104 ksi Von Misses tensile strength] for various case head designs. He often would make charts for us for the limit of case heads normalized to "3/4 hard cartridge brass", or sometimes "H06 Tempered C26000 Cartridge Brass".

If industry uses HS03 as a standard, then the range would be +/- 7%, which would be reasonable fit for Ass-Clown's calculations to fit my overload brass yield threshold data to fit Quickload predictions for absolute magnitude of pressure. By this I mean there is a fit for the absolute magnitude is tracking the HS03. More on the range of variation below.

http://www.lfawire.com/c26000.htm


Per my own experiments in various brands of brass overloaded until the extractor groove expands, the powder range required is as great as +/- 10% when comparing S&B vs Starline pistol brass, but more like +/- 2% when comparing Remington, Winchester, and Lapua rifle brass.

And yes I know that +/- 2% powder charge is not +/- 2% pressure change, but powder is what I measure when I hand load for my guns.

This IS a handloading forum, remember?

What does it all mean?
The variation is brass hardness from brand to brand is on the order of the variation in pressure signs from shot to shot with the same brand.
Therefore, the hardness of the brass does not seem make too big a difference in looking for pressure signs in Mauser case heads, despite Davis' ad hoc conjecture.


What does all THAT mean?
Brass has very consistent hardness from brand to brand, much more consistent than loads from load book to load book.
If you have the where with all to read pressure from your brass, and have a strong rifle, you can develop a much better load than you can read from a book.
But if you are ignorant or stupid, use the book.

Tnekkcc

In the Davis quote provided perhaps you should pay a little more attention to the last sentence;

quote:

Indeed, if chamber pressure could be determined with satisfactory accuracy be so simple a process as measuring the diameters of fired cases, the cost-conscious manufactures of ammunition would long ago have abandoned the construction and use the of expensive pressure barrels and copper crusher or electron transducers.

Davis is stating that using CHE pressure, even maximum pressure, can not be determined with satisfactory accuracy. Given that Davis is correct a yield strength variation in cartridge cases of 20,000 psi then is roughly a 23-24% variation pressure wise. THAT is a lot of unknown pressure to guess at. Let us remember that the 70,000 psi area is into "proof load" pressures for most Mauser head cartridges. A 90,000 psi case is well into catastrophic failure range.

I'm not sure where or how you come up with "3/4 hard cartridge case" but if we look at the charts in the site you provided closely we see the yield stregth listed as 70 KSI (70,000 psi) for "round, half round and square wire". For rolled "flat wire other than square" we find the 3/4 hard KSI yield to be 57 (57,000 psi). The head of a Mauser type cartridge case is not a solid round wire of brass. It has the flash hole trough it, a primer pocket in it and an extractor grove. Could you explain then how these KSI figures apply to cartridge case heads?

Would not an independant test of the case head for yield strength be better? It is rather apparent that without the actual yield strength of the lot of cartridge cases you are just guessing.

You are absolutely correct; this is indeed a reloading forum. However to advise reloaders to load until the case head fails (now you're talking expansion in the extractor groove also) is quite irresponsible. Some of us with considerable experience many times DO load much better than is in "a book". However, "better" does not mean dangerous. How do you know your loads are "better" without a chronograph?

"But what does it all mean?"
Brass hardness IS NOT consistant from brand to brand. Look at your own example of Starline and S&B vs others. If we assume Davis to be correct (30% error) or even your un-named (+/-7% is a 14% error) source then we see a wide range of variation in case head hardness any way we calculate it. In my CHE days I found considerable difference between lots of Norma, Winchester and Remington also. I still find difference in hardness between them.

As to your last two sentances; that is your opinion and it speaks for itself but not well of you. So I will leave it at that.

BTW; who was your father and what weapons did he design? Just for personal knowledge as I may have used them in Viet Nam.

Larry Gibson

/

quote:

Originally posted by 303Guy:
Would this all cause erratic ignition, or should I be looking at my rifle's barrel or my re-loads?

a weak FP strike can cause erratic ignition, excessive headspace can too. can you post a pic of your fired primers? a little off center is OK.