quote:

Originally posted by Bobby Tomek:
Hot Core wrote:

quote:

But, I'll try to "Dumbitdown" for ya'!"

I seriously doubt the level could go any lower.

If you say so. So, what to do?

Obviously I can't get the "How to use" portion of the never improved upon, always reliable, never fail, totally dependable, relatively inexpensive, completely repeatable, CHE & PRE down to your level.

WaIt A MiNuTe, maybe you could get alf to explain it to you!

I will try to go dumber.


Even if the absolute pressure could be known, that would not the best predictor of the short brass threshold.... sampling the brass life is the best.

You guys need to get a life. No one here NEEDS either of you to explain anything.

I fully comprehend what you are saying. But what I am saying is that your method is not the final word in pressure indicators. If it would be, ALL manufacturers of powder, bullets and ammo would use NOTHING ELSE.

Now, read the text below three times v-e-r-y s-l-o-w-l-y:

There are far too many variables that CHE and PRE can't account for and thus will not always give one a true indication of pressures. These measurements are tools -- nothing more, nothing less -- and should not be regarded as gospel.

You have to be both intelligent enough and not so narrow-minded that you can read and understand all indicators, not just a set of numbers from two measurements that any 5th grader could extract.

(If need be, my 5-year-old twins are available later this afternoon for a tutoring session if this is still too complicated. They could probably work you guys in. )

quote:

Originally posted by Bobby Tomek:


Now, read the text below three times v-e-r-y s-l-o-w-l-y:

There are far too many variables that CHE and PRE can't account for and thus will not always give one a true indication of pressures.

Ok, I read it over and over.

Now you read this over and over.

The peak pressure does not matter.
It is the effect of pressure on the brass that matters.

tnekkcc

Larry,
I don't see how this is doing you any good.

Does me a lot of good, I don't blow up guns like you do.
-------------------------------------------------------

The threshold of brass yield is then between 29 gr and 30 gr.
If it is 29.5 gr, then backing off 6%, the correct max load is 27.7 gr per Vernon Speer's 1956 technique.

Interesting to note that with modern pressure testing Speer does not even use Vernon's 1956 technique any longer and haven't for some time. The pressure measuring equipment of today is far easier to sue and allows more rounds to be tested and gives much more information. Speer found that Vernon's 1956 technique allowed for some very interesting pressures to say the least and they backed off accordingly.-------------------------------------------------------------
----------------------
What does it all mean?

It simply means there are too many variable with CHE for it to be a reliable indicator of pressure. It only indicates when that particular lot of brass with that particular case failed becuase of high pressure. That high pressure is many times more than should be used with a particular action even if backing off 6%.

Why did Hodgdon back off 10% on 223 and 13% on 308, when 6% is the correct amount?
Read my essay by Googling ""How to write a mediocre load book" second revision"

Modern pressure measuring equipment has allowed manual publishers to re-evaluate there previously published data. I appears from your writings that you are still stuck with 1956 technology.


Larry Gibson

quote:

Originally posted by Ackley Improved User:
Larry, what's wrong with 65,700 PSI? Maybe that's within the elastic limits of your brass? AIU

It may be within the "elastic limits of your brass" but it certainly isn't within the published and accepted limits of the Contender, the AR15/M16 or the M700 or M70 that I shoot it in.

Larry Gibson

quote:

Originally posted by Bobby Tomek:
...Now, read the text below three times v-e-r-y s-l-o-w-l-y:

There are far too many variables that CHE and PRE can't account for and thus will not always give one a true indication of pressures. These measurements are tools -- nothing more, nothing less -- and should not be regarded as gospel.

(If need be, my 5-year-old twins are available later this afternoon for a tutoring session if this is still too complicated. They could probably work you guys in. )

Hey Bobby, I'm always ready to learn something about Reloading that I'm not aware of. Low-and-behold, I do believe the 5-year olds might know something I do not know that apparently you have taught them.

I'd be much obliged if you would have them list 4<->5 of those (far too many) "variables that CHE and PRE can't account for". And if they would be kind enough to tell me what it is about the specific Variable that makes it that way, I'd sure appreciate it.

I have a feeling we are not talking about the same thing, but perhaps they know something I do not know about CHE & PRE.
-----

I appreciate you taking the time to help me out.

You still have not answered my question: If the CHE and PRE method is so perfect and so foolproof in its application, then why don't all ammo, powder and bullet manufacturers use it exclusively???

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by Ackley Improved User:
Larry, what's wrong with 65,700 PSI? Maybe that's within the elastic limits of your brass? AIU

It may be within the "elastic limits of your brass" but it certainly isn't within the published and accepted limits of the Contender, the AR15/M16 or the M700 or M70 that I shoot it in.

Larry Gibson

Larry, where can I ready about the published/accepted limits for a Rem M700 or a Win M70? Regards, AIU

Larry,
I used to go to the Puyallup gun show and fill my car with guns.
I would take them apart to see how they were designed, I would clean, lubricate, reassemble, and try to blow them up in a load work up. After a while, I could just look at a gun and know what would happen.
My father, chief engineer of a fortune 500 company for 40 years and a couple dozen gun patents, thought that I was nuts.
When I pointed out that he started out with trigger strings too, and I was keeping detailed records, then he was ok with it.
I did not start blowing up guns until 10 year ago.
Before that I was deigning switching power supplies for medical and aerospace.
If I disabled my safety circuits and overloaded the system until it blew up, I would learn something.
There would be holes in the ceiling, but I am too cagey to get hurt in my explosions.
I would beef up the parts that broke and go higher the next time.
My competition would run a large number of supplies in an oven and wait for statistics.
I would make supplies that could run reliably at 400% of rating, and then put back in the safety circuitry.
That way I quickly produced very reliable designs for my clients.
Eventually other consultants sprang up with "highly accelerated stress tests" [HAST] services and performed the process as separate from the designer.
With my testing of CZ52 pistols and some testing done for me at the Jet Propulsion Laboratory on the barrels, I was able to identify and document deign and quality flaws and get Accurate Arms to change their data book.
And I share the information about guns and handloading for free. Power supplies I charge for help.
What does all that mean?
My blowing up guns benefits everyone.

--------------------------------------

The load book industry has really taken some wrong turns.

"Speer 6" 1964 38 s&w special 160 gr. soft point 11 gr. 2400
"Speer 6" 1964 357 mag 160 gr. soft point 15 gr. 2400
Midway "Load map" 1999 357 mag Speer 160 gr. soft point 10.9 gr. 2400


What went wrong that Midway could get the max loads so far off and make
a useless load book?
How can 357 mag max have gone below 38 Special?

The "Load Map" says they used an "Oehler System 83 and piezoelectric transducers, the latest
in industry standard equipment".

This is nuts.
This is a wrong turn.

When you make a wrong turn like that, it is time to re think how you got there and what the real objectives are.
They build up a gun technology, and then try to approximate the pressures they are using so they have a standard.
Most of a century later, when they measure pressures differently, the standards are found to be different from the traditional loads, but they change the loads instead of the standards. That is nuts.

So the load books get wimpier and wimpier.
And on line we interact with those that think the absolute pressure has great use for individual hand loaders in strong rifles.
I have to keep trying to fix it... for free.

quote:

Originally posted by Ackley Improved User:

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by Ackley Improved User:
Larry, what's wrong with 65,700 PSI? Maybe that's within the elastic limits of your brass? AIU

It may be within the "elastic limits of your brass" but it certainly isn't within the published and accepted limits of the Contender, the AR15/M16 or the M700 or M70 that I shoot it in.

Larry Gibson

Larry, where can I ready about the published/accepted limits for a Rem M700 or a Win M70? Regards, AIU

You could try Remington and Winchester for starters. They may or may not tell you what they "proof" their rifles at but I'm sure they tell you what pressures not to use in their actions. Besides, notice that the .223/5.56 is used in far more gas guns than bolt guns. Considering the gas system of an AR designed to operate at the standard MAP of 55, 000 psi then is it one might wonder of the damage the use of loads with a MAP of 65,700 psi may be doing. In this case there was no increase in CHE so if one were using Hot Core's favorite method of CHE and worked up a similar load we have to wonder of the damage being done to the rifle. Besides all that if you are the ragged edge of the elastic limits of your cases and some condition (like temperature increase, increased fouling of the bore, etc) puts you over the top then you might have to just kiss your rifle good bye and maybe your ass too.

You could also look at the SAAMI specs for the highest pressured cartridges used in them (look for the Maximum allowable Pressure not the Maximum Average pressure). The highest you will find is 65,000 psi and that is not for the .223/5.56. The 65,700 psi I reported was a MAP. The maximum pressure I recorded was 68,300 psi(M43).

Larry Gibson

tnekkcc

Hate to break this to you but blowing up rifles with hot overloads is not exactly a rare talent in the reloading world. Many have done it. You are quite correct in one thing; "My blowing up guns benefits everyone." Everyone learns how not to blow up guns by overloading them in the first place. Those who managed the exibition of gun destruction learned that on their own with little help from your exoerience.

Loading a gun to destruction is fine if you want to do it. Apparently you were somewhat safe in that you never got hurt and hopefully no one else did with your experiments. However, to load a rifle one intends to keep and get long useage out of to the ragged limit of destruction and then backing off is not really a good way to do it. First of all it doesn't take much to go over the top and then you have a ruined gun. Additional shooting proof level loads in many rifles is not good for them and leads to the early demise of them (destruction in other words). Most of us do not want to load to the ragged edge of blowing primers and going beyond the elastic limits of the cases. We would just as soo stay within safe limits, thank you.

BTW; One has to wonder if your father wasn't correct in his intitial assesment of you.

Larry Gibson

I have to overload the guns, so I can find out which ones are stronger than the brass. It does not seem to have been made public anywhere in the literature, other than Ackley and some surplus actions.

The Win M70 can take more than the large boxer primer Mauser case heads. The primers fall out of the 270 when I over load it.

The .223 case head can take more than the Mauser case head. AR15s can handle the primer pocket doubling in size. That is a tough action.

I chambered a Rem700 today in 6mmBR.
That cartridge can take more than the 223 case head.
I will see what the Rem700 can take.

Curiously, the 6mmBR and 9x23mm do not have SAAMI registered pressure, and we just have to make up some loads.

When we work up a load for those cartridges, what do we look for in a max load?
Maybe a safety margin below the threshold of long brass life?

Gentlemen, read what tnekcc is saying about the methodology behind brass deformation being the most useful indication of the long term suitability of a given load, if brass life is a concern to you.

Absolute pressure readings would be nice to know of course, but the correlation between absolute chamber pressure and absolute safety of the cartridge/chamber/barrel system is a sort of plateau until the point of inelastic deformation is reached. That point cannot be reached without severe brass deformation in the preceding loads working up to that pressure .

The average reloader is most interested in brass life, at £80 a hundred for my Lapua brass I certainly am, for that purpose a methodology for measuring brass pre and post firing is needed, the PRE and CHE seem as good as any and deal less difficult than most, with the degree of difference for any given load being the important thing.

No such thing as absolutes in talking about essentially uncalibrated systems.

There, I agree with tnekcc

Regards,

GH

quote:

Originally posted by Ghubert:
...at £80 a hundred for my Lapua brass I certainly am, for that purpose a methodology for measuring brass pre and post firing is needed, the PRE and CHE seem as good as any and deal less difficult than most, with the degree of difference for any given load being the important thing.

Amir,
Would you share some of your CHE testing results with us?

quote:

Originally posted by Bobby Tomek:
You still have not answered my question: If the CHE and PRE method is so perfect and so foolproof in its application, then why don't all ammo, powder and bullet manufacturers use it exclusively???

The Bullet, Powder and Cartridge manufactures have invested $$$Millions$$$ into all kinds of Pressure Testing Equipment over the years. Stuff that is 10-25x the cost of a SGS(Lab).

Mostly for Redundance of Testing parameters. CHE, PRE, CUP, Piezo, SGS(Lab), they use/used them all. A properly Calibrated SGS(Lab), with exact Internal and External Barrel measurements(requires a CMM and a long probe) and having the Software Regulated properly for the SAAMI Reference Ammo(Calibration to a known Standard) works right well in a "Controlled Environment"(Lab). When those conditions(Lab) are not met, then the Data becomes information and degrades in value as each requirement is ignored. Of course, a SGS(Lab) will never work as well as a Piezo, but the Piezo takes more time and more money to operate.

In a Manufacturing environment, the actual Integrity of the Strain Gauges and Connection Wires must be Verified on a continual basis to ensure the routine shooting Vibration has not trashed their connections. No Quality Program would Certify the SGS(Lab) without that.

Simply running the SGS(Lab) is not of any help if the Limit of the Wealest Link in the Firing Process(the Case) is unknown. And of course, there is no SGS(Lab) or HSGS(worthless) made that can tell you how the actual Primer Pocket is responding to whatever the Load they are Testing.

There are only two ways to know what is happening to the Primer Pocket; either reload the Cases to determine the Change in Primer Seating Pressure with Measurable Primer Insertion Force Equipment, or to measure the Primer Pocket Expansion(EGG or CHE). None of the other Pressure Devices, regardless of the cost, can tell a Reloader(or the Manufacturer) what the most important aspect of a newly created Cartridge is, except for measuring Case Expansion.

This answer has been covered before, numerous times. The factual answers never changes regardless of how much anyone wants them to. I really thought you would have remembered all this. But it is not a problem to repeat it and perhaps a Beginner will actually learn something if they get this far.
-----

Talking about "Learning", I'm still ready. So, Bobby, what are simply 4<->5 Variables coming from your List of those (far too many) "variables that CHE and PRE can't account for".

quote:

Originally posted by onefunzr2:

quote:

Originally posted by Ghubert:
...at £80 a hundred for my Lapua brass I certainly am, for that purpose a methodology for measuring brass pre and post firing is needed, the PRE and CHE seem as good as any and deal less difficult than most, with the degree of difference for any given load being the important thing.

Amir,
Would you share some of your CHE testing results with us?

Amir

Not sure that Ghubert has any CHE testing to share but I do. Some years back, before I knew any better, I was using CHE to work up some loads in an 8x57. I was using the Hornady 220 gr SP and could find only a little data for it. This was well before Gore "invented" so I didn't have the benefit of tnekkcc's expertise to draw upon. I had 200 U 42 '06 unfired cases that a friend had pulled the bullets and used them and the powder. He didn't want to mess with the corrosive primers so he gave the primed cases to me. I deprimed them and reformed them into 8x57 case.

I was working up a load using IMR4350 in .3 gr increments (weighed). The original M98 barrel was in excellent condition annd had a long throat allowing the 220 gr bullets to be seated to mag length. This gave maximum powder capacity as the base of the bullet was at the base of the neck. I was using WLR primers.

All was going real well and I was about 1 gr from the max published load. The Oehler Chronograph was giving just over 2400 fps and the cases exibited little to no PRE and no CHE. I fired the first shot of a new string of 5 shots with .3 gr more IMR4350. The primer blew. and I mean it blew so that the primer fell out when I opened the bolt.

There was no increase in CHE and very lttle perceptable PRE. The bolt opened as normal. Being young and dumb and still believing in CHE I fired another round. The primer blew again only this time the bolt exhibited some stiffness when opening. However that second case also showed no CHE oand little PRE. I though then that I may have messed up the load but was puzzled by the blown primers (and obvious sign of high pressure) and yet no CHE.

I ceased testing and when I returned home I pulled the bullets of the remaining 3 rounds. They all checked out exactly as they were supposed to with eactly .3 gr more of IMR4350 than the previous string. Then being really dumb I thought I had still messed up and only bad luck had me pick the 2 messed up loads to fire. I reloaded the remaining 3 shots and headed back to the range.

Well I was lucky because after the first shot blew the primer again I said enough was enough and it wasn't me. It was then that I seriously begin to doubt the reliability of CHE. Subsequent tests have proven that I was correct in my doubts of CHE; it is not reliable.

Now subsequent to the aquisition of the M43 Oehler PBL I just had to know so I loaded some of the same load into the same U 42 cases. I still had a few of the 220 gr bullets left from that same box of them. However the lot of IMR4350 was different (30+ years newer) and I was using new WLR primers. I shot 2 shot strings working back up to the load that did not blow primers. The test rifle was also different as it was a Yugo M24/47 in excellent condition. The OAL of the loaded rounds was the same. Well let me say that I now have no doubt as to why the primer pockets blew. The pressure of the load that did not blow the primers was in the low 70,000 psi! Adding the additional .3 gr put it over the top and the primers blew. The cases used in this test had been fired several times since the first test but knowing any measurement wouldn't be that meaningful I measured for CHE anyways. Again no increase whatso ever.

Now, then that is two such cases, this one and the previous mentioned Winchester .223/5.56, of the failure of CHE measurement to provide any indication of high pressure. I have several others. I still have one of the U 42 cases with the blown primer. I keep it on my loading bench to remind me of the stupidity of my younger days. I some one wants to see some pictures of it I will take some and email them to you. Just give me your email address.

Larry Gibson

I did not know how complicated the calibration process was.

I was working as a power supply consultant for Physio Control ~1993, when they signed a consent decree to be shut down by the FDA for building life critical devices without validated and verified processes.

I got roped into the fire drill to restart the company, and I had to calculate the error build up in measurements made by instruments, when those instruments are calibrated by calibrators that are traceable to the NIST.
I had to design a test to test the test.
I had to then get the instrument re calibrated and find out if the instrument was in fact still in calibration, irregardless that the instrument was still within it's calibration cycle.
Instruments typically have a calibration sticker that is allot like the expiration date on a quart of milk.
Calibration laboratory supervisors are like a cross between a piano tuner and a concentration camp commander.

Having made those measurement accuracy calculations, and knowing how hairy they can get for some simple tests, I could only imagine the number of engineering hours it would take to calculate the accuracy of a strain gauge measurement and then validate and verify that accuracy.

I going to guess that in house, a strain gauge bonded on a rifle barrel, Wheatstone bridge, power supply, instrumentation amplifier, and storage scope, etc. would cost $100k to set up and $3k every 3 months to maintain. That price would be a deal killer, but if enough people did it, there might spring up a service that did high quantity, and would change a few hundred $ every 3 months to keep a calibration sticker on the setup and do return shipping.

I am going to guess that the accuracy that can be calibrated in with the ratio of gauge resistance to pressure ratio measured and linearity measured, and offset measured and compensated, would be +/- 1%, but there might be cumbersome manual correction tables, if the software was not non linear calibration friendly.

I am also going to guess that when a guy tells the wife he in going to spend $100k for a little sticker on his rifle, she is going to ask, "What do you need to know the pressure for?".

I have worked on jet engine starter/generators with strain gauges on the shaft to measure the torque. We put a torque wrench on the shaft and get a few readings for the lab book. We put "indication only.. not for production measurement" stickers on the gauge and RF transmitter and receiver.

Harold Vaughn's book on accuracy facts does about the same Fred Flintstone calibration, with a strain gauge on the rifle, and loads up the chamber with hydraulic fluid and a dial indicator pressure gauge to check the linearity and resistance to pressure ratio at the lower pressures. From that, he infers and extrapolates a pressure measurement when firing his 270.

I tried to make these issues more salient with the popcorn metaphor:

quote:

"How to write a mediocre load book" second revision

1) Get all the free load data from powder manufacturers; Alliant,
Accurate Arms, Hodgdon, IMR, Vihtavuori, and Winchester.
Ignore Norma, Nobel, Rex, Scot, and Ramshot.

2) Buy the load manuals from the Powder manufacturers that sell them;
Accurate Arms, Hodgdon, and Vihtavuori.

3) Buy the load manuals from the Bullet manufacturers that sell them;
Speer, Sierra, Hornady, Lyman, and Nosler.
Ignore Barnes, Swift, A-Square, and Lapua.

4) Load development:
You need safety margin. If you don't know what that is, put some popcorn
in the microwave for one hour. The instructions on the bag say 2
minutes, and smoke stinks up the lunchroom in 10 minutes.
It stinks up the whole building in 15 minutes.
That [10 - 2] = 8 minutes is safety margin.

5) Writing the loads part of the book:
Reduce the powder manufacturer's max load by 5%. That is your max load.
Reduce your max load by 10%.
That is your starting load.
Paraphrase any anecdotes about the caliber written in the bullet
manufacturer's load books.

6) Calibrating test equipment: The only thing that counts is a calibration sticker. To make one, on a piece of paper, write, "Popcorn: minimum 1.8 minutes, not to exceed 2.1 minutes". Tape that paper to the front of the microwave. Your equipment is now calibrated.

7) The other stuff in the book:
Find someone who handloads and take pictures of his hands while he loads
a cartridge.
Paraphrase the pages of text in the load books you bought; accuracy,
safety, blah, blah, blah...

8) Try to do a good job:
With $200 outlay and an afternoon's work you can sell 10,000 books at
$10 each wholesale and $3 each to have printed, you will make enough
money to pay the rent for a year.

HOW TO REVISE YOUR LOAD BOOK.
1) Wait at least a year, or until the first printing has sold, whichever
comes last.
2) Get the latest free load data from the powder manufacturers.
3) Look for any new powders or calibers that were not in your first edition.
4) To add these new loads, reduce the loads by 5% for max load, and that
by 10% for starting loads.
5) Charge $12 wholesale per book. Make the money last until you write
the 3rd edition.

Cross marketing:
Find some guy who makes benchrest bullets in his garage and get drunk
with him. Fix him up with your sister. If you could start selling his
bullets by featuring them in your book, you would both benefit. You
could find some surplus "blems" to fill in the product line, and he and
your sister may spawn a gun culture dynasty.

The End

Editor's note:
Last year when we first announced the "How to make a mediocre load book"
project, we used some different data. Someone suggested that it was fear
of law suits that made us change. Nothing could be further from the
truth. It was just that some new very powerful Asian microwaves were not
compatible with Beareto's Organic Popcorn . And we found a way to more
accurately measure time. The hour glass technology we were using has
been replaced with quartz-crystal oscillators and flip flop based
counters driving blinking light emitting diode displays. We feel that
the load book writer should start at 1.8 minutes popcorn microwave time
and work up carefully looking for burning signs and never exceeding 2.1
minutes.

We have received some personal messages asking if it was the Lee book
lifting data or the Speer 12 and 13 making up pressures and velocities
that the project is about. Neither could be further from the truth. In
actual fact, we are all about that an average American has the
opportunity, in few hours and for a few hundred dollars to write a
mediocre load book on a par with many of the other mediocre load books
available today.

As an addendum I hasten to add: We have had some complaints that 2.1
minutes will not pop all the kernels, and some load book writers have
been exceeding our published limits. This is dangerous and foolish. If
there is a fire in which someone dies, the load book writer making the
pop corn could be tried for murder.

It is much better to be safe and sane and spit out the "old maids" that
don't pop .

Larry,

Attached is a quote from a designer/engineer who worked for Winchester (reported as instrumental in designing the left-handed Win M70) and Kimber/Montana rifles. I won’t give up his name, because I want to protect his privacy, but here is the quote…

“Modern bolt action rifles should take 150,000 psi or better. It also depends on the duration of the pressure, or impulse. Some of the new calibers have proof loads that may reach as high as 105,000 psi and still be in spec. Of course you do not want to subject them to a steady diet of these loads.”

Thus, please explain to me why a modern bolt action rifle would blow-up from one shot at 65,700 PSI (~44% of 150,000 PSI) – even following many shots at 65,700 PSI.

Regards, AIU

PS. I do agree with your observation that when you exceed the low 70,000 PSI range (i.e., ~75-80,000 PSI) you can count on blowing primers on a regular basis. The escaping gases from the primer pocket could cause harm to your eyes, hence always wear eye protection.

quote:

The original M98 barrel was in excellent condition...

AIU, How many gunsmiths would consider Larry's 8mm military rifle "modern?"

And Larry, your problem might begin cause you stopped firing more primer-popping rounds than 5. I believe Hotcore's CHE measuring instructions say 9-10 are needed so that the average is statistically significant.



Are you sure you didn't load .323" bullets into a .318" bore barrel?

Larry,
Have you ever tried measuring the primer pockets of the cases that blew the primers.
And what does your description of blown primers mean? Blown out of the primer pocket, pierced or leaking?

Here's another article about the strength of modern bolt-action rifles for those who'd like to become informed. Regards, AIU


The RiFles Of Dakota Arms: RiFles to dream on From the high plains

(Guns Magazine, Feb, 2002 by Dave Anderson)

Sturgis, South Dakota, is best known to the public for its annual motorcycle rally that draws over half a million bikers to the normally quiet little town. To shooters, hunters and collectors of fine firearms, Sturgis is known as the home of Dakota Arms -- maker of distinctive, elegant hunting rifles and shotguns of uncompromising quality.

The company was founded by Don and Norma Allen. Don Allen is a former pilot, and since 1972 he has been making custom rifle stocks in his spare time. Allen noticed that pre-'64 Winchester M70 actions -- favorites with lovers of fine hunting rifles -- were getting more scarce and expensive. He also felt the M70's action could be improved. So with typical American entreprenurial spirit, he went ahead and built his own.

Allen and Pete Grisel designed the Dakota 76 action. It is similar in function and appearance to the pre-'64 Model M70 but with more Mauser 98 influence. In discussing these changes, a brief digression is in order. Rifle enthusiasts like to argue about which action is the strongest: In fact, all current commercial actions have a huge margin of strength. Bolt-actions are typically strong enough to handle pressures of 150,000 psi or more.

The brass cartridge case, however, will take pressures in the 80,000 psi range. Since commercial ammunition is usually loaded to maximum pressures of 55,000 to 65,000 psi, there is an ample margin of strength -- but the cartridge case will fail long before the action does.

Why not use a stronger material such as steel for the cases? Because brass has an excellent combination of strength, pliability and elasticity. When the gun is fired, the pliability lets the case expand to tightly grip the chamber walls, which seals off the powder gases from coming back into the action. When the bullet exits and pressure drops, the elasticity of the case lets it spring back to near original dimensions, allowing the case to be extracted. Although strong, steel cases wouldn't seal off the chamber as well as brass, wouldn't extract as easily, and would be subject to rust.

When comparing actions, it's not a question of strength. As stated before, steel is much stronger than the brass cartridge case. The question is, in the event of a case failure, how well does the action protect the shooter from the escaping gases? Occasionally we hear accounts of how someone had a rifle "blow up" but miraculously wasn't injured. Actually the rifle didn't blow up (if it did, the shooter likely wouldn't be around to talk about it). What really happened? The case failed and the action controlled and vented the escaping gases away from the shooter, just as its designers intended.

A hundred years ago when technology was less advanced, case failures from poor brass were more of a concern. Today's manufactured cases are of such uniformly high quality that such failures are virtually unheard of. Now when a case fails, it is almost always a result of shooter error: firing the rifle with the bore obstructed, loading the wrong caliber cartridge, or poor handloads with excessive headspace or the wrong powder.

The Mauser 98 action protects the shooter from failures as well as any, and better than most. It has a "flat" breech in which the cartridge case is enclosed by the steel chamber right up to the extractor groove. If the case does fail, escaping gases going down the firing-pin channel in the bolt are vented through two oblong slots in the bolt, down the left lug raceway in the receiver, and out to the left through the thumb slot (which facilitates magazine loading with stripper clips) in the left receiver wall. Gases going past the slot are deflected away from the shooter's face by a flange on the bolt sleeve.

The pre-'64 Model M70 has several Mauser features but also some differences. Like the 1903 Springfield, it has the breech end of the barrel coned to enhance cartridge feeding, which leaves a small portion of the case unsupported by the steel of the chamber. However, the unsupported section is the area just ahead of the extractor groove where the case is thickest and strongest. Pressures high enough to cause it to fail would likely result in case failure at the primer with other actions.

The pre-'64 action has a small hole in the right side of the receiver to vent escaping gases. The bolt has two holes that vent gases coming down the firing-pin channel into the left receiver raceway. Unlike military Mauser actions, the Model 70 does not have a thumb cut in the left receiver wall (which would allow a large volume of gas to escape) or a flange on the bolt sleeve. The bolt-stop partly blocks the raceway, but in the event of a case failure, gases coming through the left raceway would likely hit the shooter (one of the many reasons to always wear protective glasses when shooting any firearm).

Ackley Improved User

"please explain to me why a modern bolt action rifle would blow-up from one shot at 65,700 PSI (~44% of 150,000 PSI) – even following many shots at 65,700 PSI."

I didn't say the M70 would "blow up". However it is know that rupered cases spewing hot gas into actions is not good for them. That is the real risk you run with the M700 and M70. The adverse effects of ruptured cases is a real problem If you do a search of the internet you will find several examples of "blown up" M70s and like rifles from basically ruptured cases do to over pressure loads. Besides; you're own source states "Of course you do not want to subject them to a steady diet of these loads". Thus it is evident that Winchesters technicians do not believe such loads are "healthy' for the M70.

PS. I do agree with your observation that when you exceed the low 70,000 PSI range (i.e., ~75-80,000 PSI) you can count on blowing primers on a regular basis. The escaping gases from the primer pocket could cause harm to your eyes, hence always wear eye protection.

Well, I'm glad we agree at least on that. I always wear eye protection anyways even though I no longer intentionally push pressures that high.

Larry Gibson

onefunzr2:

AIU, How many gunsmiths would consider Larry's 8mm military rifle "modern?"

I do wish you guys would get your stories straight. Apparently you criticise the M98 and then AIU gives a lengthy post of 'evidence" that states; "The Mauser 98 action protects the shooter from failures as well as any, and better than most. It has a "flat" breech in which the cartridge case is enclosed by the steel chamber right up to the extractor groove. If the case does fail, escaping gases going down the firing-pin channel in the bolt are vented through two oblong slots in the bolt, down the left lug raceway in the receiver, and out to the left through the thumb slot (which facilitates magazine loading with stripper clips) in the left receiver wall. Gases going past the slot are deflected away from the shooter's face by a flange on the bolt sleeve." So which is it? Anyways just for your edification that m98 was not damaged in the least and is still in use with a Palma barrel in .308W on it now.


And Larry, your problem might begin cause you stopped firing more primer-popping rounds than 5. I believe Hotcore's CHE measuring instructions say 9-10 are needed so that the average is statistically significant.

Sorry to upset your jab but Hot Core's instructions were not around back then. I was using the original CHE as listed in G&A, Reloader and several reloading manuals. Probably was 20 years+ later when Hot Core plagurized them into "his" instructions. He managed to mess them up anyways. BTW; The original CHE instructions said the measurement of 3 cases was enough.

Are you sure you didn't load .323" bullets into a .318" bore barrel?

That may be something you might do. I am quite sure what the barrel groove depth was, thank you.



Larry Gibson

Larger bullets do fine in a smaller bore if they can get moving a few thousands before the interference.
The pressure spike from the swaging is not concurrent with the pressure spike from burning, and so they don't add. There does not seem to be a delay caused, like with starting friction from a pinched bullet. My experiments are consistent with Ackley's:


This phenomena of large bullets working in a small bore without
pressure spikes is documented in P.O. Ackley 1966 "Handbook for Shooters
and Reloaders Vol 2" chapter 7
"additional pressure tests":
"..30 cal barrel pressure barrel was fitted to the test gun, but the
neck and throat was enlarged to accept the 8mm bullet, with the bore
remaining the standard 30 caliber. A Remington factory 30-06 cartridge
with the 150 gr bullet had been tested and previously gave 57,300 psi,
for a velocity of 3030 fps. The the bullets were pulled from two more
Remington 150 grain cartridges and were replaced with 8mm 150 grain
bullets. To everyone's surprise, although the velocity was rather
erratic, these loads averaged 2901
fps, with a pressure of 40,700 psi."

The big bullet in the small bore not being a problem is counter intuitive, as is the magnitude of trouble caused by bullets pinched by the case neck. But that is the reality.

---------------------------------
I have worked up loads in 8mm in M98s. If the brass is not being measured, the first thing to notice is a sticky bolt. A few more grains and the bolt has to be pounded open.

If the work up steps are skipped and the case head fails [Having missed the clues like the primer pocket getting larger or the bolt getting stuck], the extractor breaks in half and blows out of the rifle and back at the shooter. Some of the features blow off the bolt face. The receiver bolt bore becomes smaller behind the lugs and interferes with the bolt.

The Portuguese Berdan primed 308 brass case heads like to blow in half this way.

the report in question I presume

http://www.shootingsoftware.co...g%20your%20rifle.pdf

quote:

Originally posted by stradling:
the report in question I presume

http://www.shootingsoftware.co...g%20your%20rifle.pdf

Maybe this one:
http://www.shootingsoftware.co...20july%2019%2004.pdf

I don't know if that was before or after Hot Core whooped his a$$ real bad here on AR.

Anyway, he is an electrical engineer, like me and Hot Core.
He can memorize processes, but cannot reason reason through the goals of handloading.
I think he could pass a lie detector test over the strain gauge stuff. [I think he is sincere and not after the money.]
He may also be troubled with fear.
I believe he is afraid to work up until the brass changes.

Larry,

I've experienced blown primers many times over the past decades, and nothing serious has happened. The gases are vented away as explained in the article I posted. When it happens I smell the gases or occasionally experience a gentle puff against my cheek. The only negative effects have been a dislodged Sako extractor - which I quickly fixed - and some tiny pits on the bolt-face created by the jet of gas excaping thru the primer pocket - you almost need a magnifying glass to see them.

I've learned to read pressure signs well and I no longer have blown primers. Adding CHE to my skill set will improve my pressure sign reading abilities even more. Case heads expand has PSI increases - it happens and one can't stop it. We could quibble over how to measure CHE best, and maybe some people can't because they have the necessary skills. Although I'm inexperienced at measuring CHE, I'm a reasonably coordinated individual with reasonable intellect and I'm confident I'll master the techinque. Also, I purchased a very good micrometer (Mitutoyo Digimatic 0.00005" capabe). It was expensive, but IMO worth every penny.

Moreover, I don't shoot high-performance loads in my guns but rarely just before hunting season. When I shoot targets I load way down - likely into the 35,000 PSI range. Targets don't need much "killing." My guns will out live me by hundreds of years.

If you're careful and using modern well-manufacturered bolt-action rifles, one can safely load at 65,000 PSI and keep the upper variance below 70,000 PSI. The real problem with high-performance reloading is that you shoot out your barrel quicker - that is, accuracy deteriorates more rapidly at higher PSIs. I'm a accuracy nut and use the high PSI stuff as rarely as possible. In this regard, I've found that the larger the bore diameter the better the barrel life. Just recently, I've discovered the .338-06 Ackley Improved, which with modern bullets (225 Accubond) and N204 becomes a "338 Win Mag" when loaded up to 65,000 PSI. This is a very efficient cartridge that provides 600 yds killing power and long barrel life.

Regards, AIU

quote:

"The Mauser 98 action protects the shooter from failures as well as any, and better than most. It has a "flat" breech in which the cartridge case is enclosed by the steel chamber right up to the extractor groove. If the case does fail, escaping gases going down the firing-pin channel in the bolt are vented through two oblong slots in the bolt, down the left lug raceway in the receiver, and out to the left through the thumb slot (which facilitates magazine loading with stripper clips) in the left receiver wall. Gases going past the slot are deflected away from the shooter's face by a flange on the bolt sleeve."

Based on what I know most people quote a lot of the above about the M98 and they have never seen a serious case head failure in the M98.

1. The front slot in the bolt is a vent but is in a poor location for safe gas venting. There are several better positions that would be better. A. One would be on top but that might let more dirt get into the bolt. Maybe they should have put it on top with a soft blow out plug. B One would be on the right but that might blow off the extractor. Still I would rather have it there than on the left. However Mauser probably worried about crud dropping into the vent if the bolt is open since they would be on top. C. It could be on the bottom but that might burst the magazine box. In a serious failure the magazine box splits the stock anyway. D. Put them on the bolt so they are turned down into the magazine when the bolt is open. The vents do not get crud in them. When the bolt is closed they line up with the left lug race way so the gas blows out the back.
Assuming you are right handed, shoulder your M98 and aim it. Then open your left eye. Notice the left lucking lug race way is aimed right at your left eye.

I have seen the result of a serious case head failure in a K98. The guys face was bleeding from 20 or 30 small punctures on his forehead and cheeks. Only the glasses he was wearing saved his eye sight.

quote:

Originally posted by Hot Core:

quote:

Originally posted by Bobby Tomek:
You still have not answered my question:

...what are simply 4<->5 Variables coming from your List of those (far too many) "variables that CHE and PRE can't account for".

Hey Bobby, I've thought of 3, but they all have to do with Physical and Mental Handicaps.
1. Blind people - no Braille 0.0001" capable Micrometers.
2. No hands/arms - hands definitely required to "hold" the Case and Micrometer.
3. HSGS purchasers - they do not realize a non-calibrated, guessed at dimension, and fudge factored, Haphazard(Dr. Ohler's choice of wording)SGS is totally worthless outside a Ballistics Lab and they really should not be Reloading anyhow.

So, it appears your Bluff has been called and you have failed to fabricate anything even remotely believeable. I'm a bit surprised.
-----

Had no idea the thread would take off and hang around. August is here now and perhaps it will remain alive until my buddy gets to run his 300WSM Tests with his HSGS this Fall.
-----

Meanwhile no one has ventured a Guess at the original question except our esteemed Mr. Woods. He was correct that the "CHE Data" did not make sense. And there is also something noteworthy in the "PRE Data" when it is Averaged to make the Second Issue REAL clear.

Any of the Rookies or Beginners who do not want to endure the foolish, ignorant berating by those who do not understand, feel free to send me a PM and I'll explain what the original post can tell you.
-----

Many times when you believe you can solve a problem by tossing money at it, you typically do not understand the problem, nor what the money is actually buying.

I've already pointed out variables and situations in which "your" method has no value. But you might have to look beyond the shadow of your forever-growing, never-questioned, never-equaled, most undeniable and ever-present EGO to see as much.

My last 1:8 .223 was fed mainly a diet of 75 grain A-max bullets. The charge of propellant I settled upon for best accuracy drove the bullet at just over 2800 fps from the 26" barrel. That load showed ZERO CHE/PRE increases, and going up 1.5 grains did not either.

I was quite content with the 2812 fps load and the spectacular accuracy I was enjoying. As I had no interest in another 500 fps and blowing up the rifle, how would "your" system have been useful?

Really, now, what could it tell me that other indicators along with COMMON SENSE could not?

One more thing: when I asked why manufacturers don't abandon all their expensive systems and use CHE/PRE exclusively since it is, in your words, "never improved upon," you sidestepped and basically said, in a nutshell, that they use it since they already have it.

Well, why don't they liquidate that worthless expensive junk, trim their ballistics technicians from payroll, enjoy a much healthier bottom line and get an intern to take the infallible CHE/PREs?

Or perhaps, just perhaps, do they know something that you don't???

quote:

So, it appears your Bluff has been called and you have failed to fabricate anything even remotely believeable.

I thought so. However, it was good to do the mental exercise wondering what you "could have been" talking about.

Bobby, (notice I didn't use the salutation 'HEY' Bobby?) you should know better than to wrestle with the HC pig; you just get tired and frustrated and he likes it!

Did you ever once see where CHE\PRE measurements were equated to psi? I have load manuals going back to 1970 and I've never seen it.

Did the CHE\PRE measurements in the first post of this thread even equate to normal, MAX, or dangerous pressure? NO. Because it's only a guess. Nothing concrete to compare CHE\PRE to actual psi measured by other means. And that, my friend, is the rub. Because just like CUP cannot directly equate to psi, CHE\PRE cannot either.

I'm afraid old HC has dug himself into such a deep hole, the only thing to do now is to cover him over and let him RIP.

Who cares what is the psi in his strong rifle?
Someone still caring about SAAMI registered pressures instead of the more optimal individual hand loading objective of long brass life?
That person must be "retarded".

Who thinks they can get an accurate measurement of psi with a strain gauge on their strong rifle?
That person must be "retarded".

Where do retarded people think that registered pressures came from other than someone looking at THEIR brass in THEIR strong rifle?


The effect on the brass is what matters to the astute hand loader.
PRE & CHE do measure changes in the brass.
Who would teach PRE & CHE to "retarded strain gauge hand loaders" to progress them the next level?
That person must be a "saint".
Saint Hot Core, who battles fear and ignorance in the internet hand loading forums, by teaching PRE & CHE to help the retarded.


Saint Peter was later crucified in Rome, for teaching Christianity.

quote:

tnekkcc:

Posted Jul 30, 09 20:05
A few months ago I was doing a series of 223 experiments with Redding FL "S", Forster honed neck, Forster not honed, RCBS small base, RCBS, Lee RGB, and Lee collet dies and with loads [SAAMI registration for 223Rem is 55kpsi, these tests were at 66kpsi... ]

quote:

tnekkcc: Who cares...

Obviously you cared enough to include psi in this post on another thread.
Did you get the 66kpsi by utilizing CHE\PRE? If so, please tell us how? If not, why not?

tnekkcc,

You've used case groove expansion as a measure of impending case failure. I'm new to the game, athough if you've read my posts you'll see I'm ready to learn. I just got my blade micrometer.

At what case groove expansion (CGE) do you experience a blown primer and at what GGE do loose primer pockets begin to appear? - that is, for an '06 and 300 mag based case.

Thanks for your answer in advance.

Regards, AIU

Dave,
Out of context.

Ackley Improved User,

I use extractor groove expansion as a predictor of impending loose primer pockets.
Case failure [as I am using the term], is when the head comes off or breaks in half, is 5 or 10 more grains in a work up.
The primer pocket should double in size and the bolt handle needs to be pounded open, before the case head failure is reached.
Case head failure is a real mess.
It usually requires a new extractor and sometimes lots of other parts.
There is no practical reason to work up a load to case head failure. I worked up to case head failure many times 10 years ago, to see what happens, but it is not part of practical work ups to develop a load. It is destructive testing on the gun.
If I am just interested in finding an optimum load, I work up until the primer pierces or the extractor groove expands, and then back off a safety margin.

The pierced primer is a function of;
1) pressure-time under the curve
2) firing pin fit to firing pin hole
3) firing pin shape, firing pin hole shape, firing pin protrusion, etc.
4) speed of powder
5) thickness of the primer cup

In bottle necked rifle cases, there is plenty of time for the gas to get through the flash hole and equalize pressures. This delay line is important in 357 mag between Bullseye and H110, but not in 30-06 between 4895 and 4350.

I don't know if I am the only one, or a million guys have done it for 100 years, but I like to measure extractor groove expansion with dial calipers.
You could measure the primer pocket with pin gauges.
You could note at what load the primer falls out.

Here I am making fun of psi guys, and I am taking the indirect route myself

But I have reasons.
The primer falling out may be the first effect of pressure in a work up we care about, but it is not consistent.
It is caused by a loose primer pocket.
But getting the primer to fall out is as inconsistent as the hanging chads in the 2000 Presidential election in Florida.
Some primers do not fall out when the primer pocket has expanded .010", and some can fall out with .030" expansion.

Both are bad loads.
I like to consider that .001" per firing is unacceptable, and is the threshold of short brass life.

I could measure the primer pocket with pin gauges.

quote:

Depth min max diameter min max
small rifle primer pocket .117 .123 .1730 .1745
small pistol primer pocket .117 .123 .1730 .1745
Large rifle primer pocket .125 .132 .2085 .2100
Large pistol primer pocket .117 .123 .2085 .2100


Height min max Diameter min max
Small rifle primers .115 .125 .1745 .1765
small pistol primers .115 .125 .1745 .1765
large rifle primers .123 .133 .2105 .2130
large pistol primers .115 .125 .2100 .2120"

SAAMI specifications on primers and primer pockets per "Sinclair International's Precision Reloading & Shooting Handbook" 10th edition 1999

As you can see, a pocket should be within a .0015" range.
Pin gauge sets come in .001" increments, but can be ordered cheaply from MSC in .0005" increments ordered individually. [Yesterday I chambered a 6mmBR in a Krieger barrel with a .2365" pin gauge for a spud to bend the gimbal with the spider].

So I could order a .1735" and a .1745" in addition to the .1730, .1740, and .1750" that came with my set.
But I would have to de prime. Not so easy at the range.
And there is dirt in there [products of combustion].
Also the expansion is often not symmetrical. If I rotate the brass, and there is an expansion anywhere around the groove, I want to know it, but a pin gauge does not tell me that. Also the primer pocket expansion is not uniform over the length of the primer pocket. It can still be small at the orifice, and have a bulge in the middle. The extractor groove is the weakest point for the primer pocket, and I think the best place to measure. If the pocket bulges in the middle in one shot, it may reach the orifice in another one or two shots.

So the dial calipers on the extractor groove are more sensitive and consistent than looking for primers to fall out, and easier than custom ordered pin gauges.
And I can put calipers on each shot fired at the range before and after firing it.
I lock the calipers on the measurement, so I don't have to write down the number or remember it when I am aiming.

My 30-06 and 300WM rifles do not pierce the primers in work ups in my rifles, but get loose primer pockets.

quote:

Originally posted by tnekkcc:
Dave,
Out of context.

Here I am making fun of psi guys, and I am taking the indirect route myself

But I have reasons.

Actually, I took it as you have an agenda and were just making an ass of yourself.

So just like HC, you refuse to answer a direct question by dismissing it out of hand. That's typical.

Dave-

Thanks for calling them as you see them!

quote:

Also the expansion is often not symmetrical. If I rotate the brass, and there is an expansion anywhere around the groove, I want to know it, but a pin gauge does not tell me that.

Round holes have tolerance. A hole can be out of round slightly and still be in tolerance. Pin gauges designed to check the upper limit of a possibly out of round hole are ground to a "double D" configuration with opposing flats.
An oversize primer pocket can be detected even if it is out of round with a "double D" unless of course it deforms into the shape of a Wankel rotor. If you get a tri-oval primer pocket or case head deformation even your calipers and blade mikes will not detect it.