The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Actual CHE & PRE Data + Fabricated M43 info.Go | New | Find | Notify | Tools | Reply | |
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tnekkcc, thanks for the comeback. Regards, AIU | |||
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Dave, I am not going to cooperate with your baiting me by confusing my psi frame of reference [for case growth longitudinally in the reloading cycle concerned with case trimming] with my optimization method [radial case growth at extractor groove for finding a max useful load]. SR4759, I was selling you on pin gauges for measuring case neck, chamber necks, and die necks in reloading, now you are selling me on the double Ds. I always thought that was a bra size  The extractor groove growth, if asymmetrical, has typically two max readings 90 degrees from two minimum readings. | |||
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tnekkcc, The pin gauges are great for checking things as your suggest. I also use small hole gauges and telescoping gauges. I just added the DDs incase you want to make yourself a set of no-go guages. For checking holes the full round pin is considered the go gauge and a the MAX dim DD is the no go gauge. There are other assorted and expensive dial bore gauges but most shooters would buy another rifle or 3 first. Checking the extractor groove with a mike should be good enough. Have you ever expanded the primer pocket of a large rimmed case such as a .303 or maybe even a .45-70? I always wondered if they would take more pressure assuming the round was chambered in a decent action with a close fitting chamber. Maybe a 7.62X54 Rusky would be a good rimmed round to test at very high pressures. BTW DDs are often created with cc's like big motorcycles. A coworker once worked at Dow-Corning and said they went up to 1000 ccs. I think there are much larger displacements now. | |||
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My 45/70 handi rifle with 32 gr Unique 405 gr cast will head expand .0025" and flow brass into the extractor misfit. So both things go wrong at once. A hunting buddy has had the problem of 7.62x54R primer piercing with hot loads. When I overload the 7.62x54R, I get stopped by the sticky bolt. The 303 Brit is a great cartridge, but I have no confidence in the No 4 mk I action getting long brass life with hot loads. I have chambered a 91/30 in 30-30, but have not shot it yet. I have an 1885 clone in 30-30, but have not shot it yet. I have a Savage 219 in 30-30, but have not shot it yet. Those 30-30s should be able to go very high in pressure, given the strength of the 30-30 case head design. | |||
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Hey SR4759 and Tnekkcc, If your all's ears are burning, it is because I've been bragging on your discussion concerning the non-symetrical(ovate) EGG and CHE that occasionally occurrs. That explains another situation that can exist, which would cause the HSGS people to come "un-glued" so to speak.  Of course, the chance of them understanding what you all mentioned is about the same as finding a Buggy Whip Holder mounted on a car.  I'm sure glad there is a crew lurking in the shadows to fill in for dunceton. There would not be many Grins otherwise.  | |||
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Hot Core went to the doctor last week. His doctor took one look at him and said: "I'm sorry; I don't treat foot-in-mouth disease. But go see this guy on the other side of town. He can help you, and I'll set it all up." So off he went, stopping every once in a while to get directions since he always seemed to be a little lost and unable to decipher his doctor's directions of "last building on the left before the river." But onward he marched -- slowly, that is, since he borrowed surveyor's gear to calculate distance readings of every building he saw to see if it was indeed the one closest to the river. But all of those bends in the rivers and the steep and uneven banks required much attention to detail, so he became even more confused. His appointment was at 11:00 a.m., but ol' HC never noticed that the sun was now low on the western horizon and that the once-bustling school yard he passed earlier was now empty and quiet. Things like that -- things that us "simple, dumb folks" could understand thanks to common sense -- never came easy for HC. But onward he went, and he did eventually arrive -- just as his doctor-to-be was walking to the parking lot after a long day of work. HC didn't notice the lab coat or the ID tag on the doctor's shirt pocket and asked: "Hey, I'm HC and I need to find the office of Dr. John Doe." The good doc responded: "I am Dr. John Doe. I did receive your referral, but I'm afraid you are several hours late." Flustered, HC responded: "Can I come back in the morning?" The doctor took a couple steps toward him, looked him over and then said: "No, that won't be necessary. I'd like to help with your foot-in-mouth problem, but I don't see how I could get past that giant ego to help you." Tomorrow, HC has another appointment, but this one will be tough as it's on the south side of Main Street, 2 blocks past Wal-Mart and the first brick building on the left beyond the light. The doctors in town currently have a pot going to see how long it will take HC to arrive for tomorrow's appointment. Dr. John Doe is the favorite to win. His pick: 2 weeks, 2 days and 3 hours. Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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Yeah the Lee-Enfield is close to a total loss for high pressures. 1. Diameter of the chamber is about .010 larger than the brass 2. By design, the chamber is far longer than brass, ammunition and dies. The chamber shoulder shape is different and varies a lot from rifle to rifle. 3. The receiver is flimsy and asymmetrical so it elongates and bends under firing forces. 4. The bolt is flimsy and compresses under load. 5. The head space standards are very generous (sloppy) compared to the thickness of case rims. 6. The brass sold in the US is thin walled suitable for use in conventional chambers and actions but is unsuitable for use in the Lee-Enfield. | |||
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Ackley Improved User 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. It is good, I guess, that "nothing serious has happened" in your cases of of blowing primers. I can tell you from personal experience that it is a very small step from a plown primer to a blown rifle. I have been involved in blowing up 3 rifles over the years two of which were modern bolt actions; a M700 Remington and a Mauser 3000. 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. The problem, as I've adequately pointed out, is that CHE many times does not give any indication that the pressures are excessive. In the examples I've given there was no increase in CHE even though the pressure was exceeding the 65,000 psi you say is your limit. There in lies the real problem with CHE. It may be one indicator as you use it but it is not the end all sure fire thing for reading pressure that Hot Core claims it to be. So far you are successfull with it because you use it with other indicators as we all did in the past. That is all very well and is what most of us recommend. However, once again, the rub comes from the claim that it is "the" only reliable method. It is not, it is in fact quite unreliable. 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. I'm still not sure why you seem to think there is some disagreement between what you and I are talking. There isn't. I do load cartridges to 65,000 psi for use in modern bolt guns. However the example of the Winchester .223 ammuntion was that most .223 ammuntion is fired in gas guns. It is well know that gas guns will take a beating when pressures are over the design parameters. Notice i did not say the gas guns blow up. I said they take a beating and they do. They wear out and break much faster with over pressure loads. Larry Gibson | |||
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As amazing as it may seem, that sentence is true. I went 19 years between visits the last time. Maybe he forgot to add in the years. ----- For the Case head "thickness" portion of the intelligent discussion, I'd toss in any Belted Case and the new WSM Cases as being designed with more strength than most. | |||
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Larry, thanks for the comeback. I don't shoot automatics or semiautomatics, just bolt-action rifles. If I did shoot non-bolt action guns, I would load UNDER specifications. Regards, AIU | |||
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Every time I say something like, "I don't take prescription drugs and don't go to the doctor, that's for women.", then I get a finger in the grinder or something, and have to go. When my father was developing guns on the government nickel, there was a log book. If things broke, it had to be fixed. The log book would say, "unscheduled disassembly". Like wise, when my wife goes to the doctor a couple times a month, it is scheduled. My visits are more like the gun's "unscheduled disassembly". | |||
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True. It is by no means a high pressure rifle. The No4 cannot handle pressures higher than mil spec 7.62 NATO. The NoI even less so - 45,000 CUP. Still, it's not a wimpy rifle and is capable of pretty good accuracy for some reason. Regards 303Guy | |||
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The action survives the pressure, but the brass does not, for long. Ackley's quote:
My calculation:
Brass can handle .001" or maybe .002" of stretch and elastically return to former shape, but any more, and there is plastic deformation. And that assumes that the case had been fire formed and neck sized, so there was no stretching from the firing pin pushing the case forward. | |||
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HOLY COW! That's a lot of flexing! Thanks for that, tnekkcc. But there is no-way my loads are below 30K psi! Not as high as 45K psi either, mind you. I get no case elongation and almost indefinate case life! (My only case failure is due to neck splits when I neglect to anneal!) The trick is to lube the loaded rounds which spreads the stretching over the length of the case body, keeping it within the elastic limits of the brass. (And of course, the cases never get any shoulder set back during neck-sizing!) Regards 303Guy | |||
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If you put Lyman moly bore cream on the cases, the 50kpsi breakdown lubricant will help the cases slip back to the breech. Try not to get it on your clothes. | |||
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This appeal was posted July 24th. I have yet to see a public acceptance. Why? Perhaps because all the CHE data that you presented doesn't amount to a hill of beans. Did you forget to list what pressure your measurements gave? There are no conclusions. Is that what you meant when you asked, I'll say there's a problem! The data you provided is nothing but an exercise in futility. Much like your useless boasting that CHE is If there's ever a SCAM, it's your CHE predictions. Hotcore, you're the modern incarnation of the old snake oil salesman...a loud-mouthed Billy Mays wannabe, and just as annoying. Just like a miniature yapping dog...all bark but no bite. You say you've used CHE for decades. You must have hundreds of pages of case measurement data. For goodness sakes, let's see it along with your conclusions of whether the tested loads were normal, MAX or dangerous. And, of course, how you drew those conclusions. Does anyone remember the Happy Days episode when Richie Cunningham takes on a bully inside Arnold’s? After the posturing and tough talk, the bully hasn’t backed down and is ready to land a punch when Richie calls time and goes over to The Fonz? “Say, Fonz, I’m doing everything you said and nothing is working,” asks Richie. “What gives?” “I forget to tell you,” says the Fonz. “Once in your life you’ve had to have the reputation of hitting somebody.” Your timeout is over. Time to fess up, Hotcore. On the other hand, M43, and I presume, Pressure Trace presents its data in psi. It can be compared with any load manual that publishes their findings in psi. I cannot find one that gives results in CHE. Not one! | |||
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Your reading and memory are not as good as you think they are. This specific example was selected to answer a one of your incorrect posts about CHE. It makes a point, but I have no doubt that you can't figure it out. Everything you say there is True, except you are receiving info instead of Data. The only part you are missing is the info(not Data) provided by the Non-Calibrated, Guessed-at-Dimensions, Fudge Factored, Haphazard SGS is misleading at best and meaningless at worst. It in no way compares to the actual Data found in the Manuals, nor the Data provided by a properly Set-Up SGS in a Ballistics Lab. You all who bought the Haphazard SGSs, just didn't get what you thought you were getting. There is a good bit more required for the units to function properly. It is simply beyond your all's ability to get them Set-Up properly. No different than if I provided you with a TACAN, Doppler Radar, or Camera able to take flicks of a License Plate from 80Angels. Yes, the devices can work properly, but just not in your all's environment - with what you have available. It gets back to what Tnekkcc has said from the beginning(using other words) - you all got seriously PT Barnumed. Simply a $$$HIGH$$$ education expense that allows us who know what is really going on to get a few | |||
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Hot Core wrote:
--- The dictionary says: "An exaggerated sense of self-importance; conceit." And for those interested, they have just edited the entry to now include a photo of Hot Core for use as a visual aid. Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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Oh contraire Hot core, I actually got everything I thought I was getting because I researched the M43 for several years thoroughly prior to buying one. I talked with Dr. Oehler and his head technician who made the M43 for me. I have no trouble setting it up and no trouble getting reliable data from it. I have no illusions on what it will do and what it won't do. Unlike you I understand what it actually does. The pressure data I obtain from the M43 compares with the pressure data from Winchester and Federal and also compares with the data from manuals (when given in psi obtained from piezo-electronic machines). I continuously use all other previously used and recognised methods of onitoring the pressure of reloads as mentioned in the manuals including CHE. The problem is of all the other methods it is CHE that consistently fails to give proper measurement of excessive pressure. What I denote from you is not only jealousy but also simple disdain because methology is now available to some of us that easily disproves the claims you make for CHE. Your constant boyish chides are nothing more than what a whining boy does who really wants to take his football and go home because someone is better at the game than he. The problem he (you) have is you have yet to discover it really isn't, and wasn't in the first place, your football. Larry Gibson | |||
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Larry- All I can say is:  Your post hit the nail on the head.  Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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HC, once again you have been offered a chance to post any proof from your immense logbook of CHE data and once again you have done a disservice to all the newbies and CHE wannabe believers on just how CHE actually predicts case pressure. It's show and tell time. It's about time for you to put up or shut up. Instead of bad-mouthing M43 results yet again, post you own CHE results. Until you do, you'll be looked upon as a loud-mouthed coward. You're all talk, and everyone knows talk is cheap. Post your results and we'll decide whether it's relevant or not. | |||
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  And still we are waiting...  Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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I think something along these lines from another of HC's threads would be acceptable:
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I'm kind of surprised the thread is still running. Obviously a good many differences of This is the all time best thread for finding out how well a M43 works outside a Lab, where Dr. Oehler was thoughtful enough to respond to my questions. Interesting to see how much Variance between "Actual Pressure" and non-cal, guessed at, fudge M43 info is. So, anyone thinking the M43 or any Haphazard(Dr. Oehler's choice of wording) SGS provides accurate info outside a Lab, is simply fooling themselves. And it shows a complete inability to understand Dr. Oehler's words. In this thread, Dr. Oehler discusses how the variances cause the results to be "approximations". I saved this link to where a non-calibrated system is useless. But, I don't even remember it, because that is obvious. ----- I at one time thought you all had a bit of sense, now I even expect you all to argue with Dr. Oehler's comments. Pitiful! | |||
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Hot Core- Do not try and misrepresent what Ken Oehler said. THIS is what he stated, and it is what I and others have been saying all along, MUCH TO YOUR DISMAY: "It appears to me that observing fps, pre, or che are all useful indicators. Nothing more." Oops...guess you won't like that I actually read that link, huh?  Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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Hot Core- This is what Ken Oehler wrote to you: "It's apparent that we've agreed to disagree..." He did not in any way back your claims. And as to the M43, this is what he said, and I quote: "In our humble and unbiased opinion, the Model 43 is the only practical solution for the individual to measure chamber pressure with reasonable accuracy and at a reasonable price." Also, Hot Core, when you wrote: "And it shows a complete inability to understand Dr. Oehler's words," I do hope you were standing in front of a mirror.  Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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If you think that pressure readings off an individual handloader's strong rifle is better than measuring changes in the brass, then there are 100 dumber handloading forums where you can post. But at this forum, right now, that point of view may be criticized by some that understand their objectives of a load work up. A) You may have bought an M43. B) You may have bought an M83. C) You may have may have saved your money by epoxy bonding a CEA-O6-250UW-350 strain gauge [cheap] to your rifle, made a Wheatstone Bridge [cheap], powered AD8554 op amps [cheap] in an instrumentation amplifier configuration [cheap], and monitored the amplifier output with a storage scope [expensive, unless you already have one]. In any case, I'm sorry you wasted your time and money, you must learn to deal with that. Arguing with Hot Core will just make it more painful when you finally figure it out. 1) Denial, 2) anger, 3) bargaining, 4) depression, and 5) acceptance are the steps you must go through. What does it all mean? I don't know how I can help you in your denial and anger with Hot Core. I would like to be as up beat and helpful as I can. | |||
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A quick question to both factions to help me crystallise my thoughts on this if I may? Why are we, ie handloaders, interested in the pressure of our loads? To ask it another way, what benefit does a handloader gain from knowing the pressure value of his load in PSI, to an accuracy of between 2 and 10%? Regards, GH | |||
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I think there is a fear of pressure, and measuring pressure may be easier than dealing with the fear. | |||
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Hot Core Again you tap dance. The pressures in all firearms, including the factory's pressure guns, will be different just as velocities are different. That is why they have "reference ammunition". It is not used to "calibrate" a pressure measureing system but to provide a base line measurement so they can then use the difference as an offset. We have been through this several times and you still do not understand. You give your usual tap dancing answer. Interesting to note that CHE is actually the "hpa hazard" measuring system as you have no "reference brass" to base any CHE measurement on. That is, if there is any CHE at excessive pressure levels which we have demonstrated that many times occurs. As to lab conditions; You mean to tell us that your ability with CHE at the range or off the tailgate of a PU is equal to that obtained in a lab? It is not, you knowi and so does everyone else. However, if you manage your measurements consistently and there is CHE then you will have a valid point of reference. The same applies with a M43. If it is used consistently, even at the range vs a "lab" then the data given is a valid point of reference. You seem to think that what is good for you isn't good for the rest of us thus, again, you are just whining and wanting to take your football home. tnekkcc Your "dumber" comment is absolutely ludicrous given your phylosphy of "load it up until the primer blows, then back off". I have meassured the pressure of quite a few loads of different cartridges using a M43. The results are consistent and reliable. Based on pressure information recieved from Federal and Wiinchester the results from the M43 are very close and consistent to what the "big boys" get with their sophisticated pressure testing equipment. We might ask of you just how many loads have you tested with a M43 to base you opinion on? Larry Gibson | |||
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Exactly!  But fear of what?, the action blowing up or welding a case to the chamber? I see that the M43 is useful to measure pressure, I can see difficulties in an un-calibrated system but reading Dr. Oheler's post on the other thread can see that the resulting inaccuracy has been quantified. Any resulting pressure reading is therefore given with a range and that I can accept. What I still don't understand is why we need to know pressure, rather than the effect of pressure on the components of the rifle/load system under test? Mainly the brass for example. A fascinating topic gentlemen, thatnk you for your replies. REgards, GH | |||
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tnekkcc wrote:
I never said that. But what I have repeatedly said is that COMMON SENSE is a reloader's greatest asset and that CHE and PRE are only tools -- nothing more and nothing less. CHE and PRE are far from the final word in pressure indicators. And thanks to HC's link, I see that Ken Oehler said the exact same thing, though HC would like you to believe otherwise. You know, I have one particular lot of brass that is now on its 24th firing and ready for its 25th. The primer pockets are still snug, and the brass is resilient as ever -- but again, that's because I use common sense in my loading techniques. And I certainly don't push things -- be it pressures or agendas, as some here love to do. Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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If I may your phrase above is why I think the factions are talking at cross purposes here. I did not read CHE and PRE as being pressure indicators per se, in that they seemed to me to be indicators of case life for a particular load. I am therefore assuming that I will never reach the pressure ceiling of my action, before reaching the pressure ceiling of my brass, in the course of working up my loads. Is that an erroneous assumption? REgards, GH | |||
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Larry, I took a rifle I chambered in 6mmBR, Rem700/Krieger 1 in 8 twist/ Harrell brake/ Choate Ultimate sniper stock/ IOR 2.5x10x42 scope for the first time to the Issaquah range yesterday for the first time. The load was 33 gr H335 87 gr Vmax 2.290" OAL [jammed into the lands, the throat will seat the bullet that much further anyway]. I chambered another 6mmBR on a 1917 Sav99 take down 22-250, Shilen 1 in 14" twist, that does not have as tight a firing pin / firing pin hole fit. Working up loads in that rifle leads to a different load. What would you do to work up a load, rather than work up to primer pierce and back off? After the Rem700 gets it's firing pin hole bushed, I will work up new loads for it. How would you work up the new loads for the Rem 700 after getting bushed? Estimating the primer max pressure and measuring the pressure are fraught with error. What is wrong with working up to the real limiting factor, and then backing off? It just makes sense to me. How would YOU do that without working up until the primer pierced and then backing off? | |||
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Once again folks, Hotcore goes off on a tangent ridiculing the M43 instead of posting his CHE results. Has anyone else noticed that is his standard operating procedure? Dredging up old posts of his to cut down the M43 but NEVER posting CHE results, even though he keeps claiming it's the greatest. That is truly pitiful. It is like a religion to him. One big leap of faith. We must believe, even in the absence of hard facts. The AR beginners must be wandering why this is so...not a single posting EVER of his CHE results over a span of years. Pitiful. Next, he'll want us to believe he can walk on water! Such a pitiful fool he is. | |||
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tnekkcc wrote:
Why do you feel it's mandatory to operate at top pressures? What's wrong with mid-range loads -- loads that give superb accuracy and infinite case life? Most of us DO NOT CARE what the breaking point of a rifle is. We instead choose to use it in a reasonable manner that meets our specific goals of velocity and accuracy. If I ever get so sidetracked and narrow-minded that I think I have to have another 100 fps, I'll move up to a larger case instead of trying to run a firearm to the ragged edge of safety. Again, it boils down to common sense. Bobby Μολὼν λαβέ The most important thing in life is not what we do but how and why we do it. - Nana Mouskouri | |||
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Does anybody know, for certain, what Federal, Remington, and Winchester use to determine pressure when producing a batch of ammo? Let's assume (whatever it is) that it is top-notch equipment used in a lab environment. Here's my take on the CHE/PRE method: Take a factory load, fire it and use the 'after' measurements of the CH and the PR as a basis for the next load analysis (resizing to reset the PR). Why wouldn't the expansion of the PR indicate that you have now matched (or exceeded) the pressure that the factory round generated? I'm not talking about the 5th or 6th reload so work hardening doesn't really come into play. I'm asking for sound reasons that this method would not be a good indicator. I can see that if you have a strain gauge system mounted and you fire several factory rounds to establish a baseline PSI and then fire your reloads without disturbing your test setup, you could see that you have matched (or exceeded) the pressure that the factory loads demonstrated. Is that how you guys use the HSGS setups? I know from years of experience that any change in the test setup can skew the resulting data. If you are moving the test setup, connecting/disconnecting stuff, environmental factors change, etc... your results are not scientifically comparable to the previous test unless you are calibrated to a real standard. Not knocking the HSGS but I am curious about the test method and how repeatable/reliable/consistent it is. Please take these questions as educational and not argumentative. | |||
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The whole purpose of SAAMI limiting the pressures is, I believe, to prevent one from exceeding the yield point of the cartridge/rifle. It isn`t meant as an absolute maximum point. The method of exceeding the component limits then backing off may put one at a close(r) point to the maximum pressures that will damage the components, but IMO it is a better idea to work in the range of those pressure limits set by SAAMI that are not going to exceed the case, primer, or rifle and stop there. Popping a primer tells one nothing about where they are in relation to SAAMI max except that they are well past it. True, you may lose 50 fps, but you gain not only more loads from your brass but, add a safety factor if something such as warmer ambient temp`s, or a new hotter powder lot appears that threatens to put you back over the edge. CHE is the same basic princple, add powder until you exceed the yeild strenght of the case head and back back down to where it doesn`t occure. Most agree primers pierce and case heads expand measurably at pressure in the 70K/75K range. No cartridge today operates at over 65K psi. How many grains of powder from a load that blew a primer do you have to reduce to get it back down to 65K psi? If these methods work so well, why don`t the powder and bullet companies continue to use them in developing their manuals as they did in the past? Why are older reloading manual loads being reduced from what they once were, when redeveloped with newer strain or piezo methods? Staying within the max listed in a reloading manual should keep one at a safe point. This isn`t however always true due to the variations in chambers, bores, components, and tolerance stack amoung them. If one works up to book max and doesn`t see sign of excessive pressure he may be safe in figuring the load is at, or very close to SAAMIs recommendation. If he sees a sign of pressure, the warning to back off when it 1st appears is prudent IMO. You are now operating with the old "it`s over the yield point" method and you don`t know where you are. M43 or Pressure Trace are not perfect either. They do however have greater resolution of pressures then the old methods. One can see his load approching or exceeding a set limit, that even if slightly off is likely closer to SAAMIs idea of a safe max then one will get with a micrometer. Factory ammo can be used as a referance point with them, just as referance ammo is used in the lab. Is it going to tell you you are exactly at 65K psi? No! It will tell you however, when you are within ~ a thousand psi of your referance and that is much closer then you can "guess" your pressures to be useing other methods. Add a cronograph and yes, keep an eye on primers and case expansion, and you should know where your load is to a very close degree. Some seem to be of the mind that they have to run things at the ragged edge. If primers pop at 55 gr of abc powder but don`t at 54.8gr then that is a safe realistic limit for their rifle. I tend to think they also feel if their engine red lines at 5500 rpm but the valves don`t float until 5700rpm then holding the needle a cunt hair below the 5700 mark must be the rpm to run it at. tnekkcc I don`t want you to feel I`m singling you out because I used your quote. You`re not the only one that appears to operate this way. We all have our idea of how, and why we look at pressure. No one really knows for sure what they are getting outside of a lab and some maybe not even there. The whole idea is to keep it safe, and for most accuracy is just as important if not more so then velocity. This arguement as to what "max" is and how to measure has been going on for years. I doubt it will ever be settled. 1st, there appears to be two lines of thought as to exactly what "max" is. One trusts SAAMI and their numbers, the other believes if it hasn`t blown up yet it is good to go. Measuring methods are the same way. One believes mechanical measuring is best, the other trusts electronics. Both will help you keep all your fingers, one will do it with a lot less strain on your equipment. ------------------------------------ The trouble with the Internet is that it's replacing masturbation as a leisure activity. ~Patrick Murray "Why shouldn`t truth be stranger then fiction? Fiction after all has to make sense." (Samual Clemens) "Saepe errans, numquam dubitans --Frequently in error, never in doubt". | |||
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There is no SAAMI registered pressure for 6mmBR. Would they make if 70kpsi for loose firing pin holes and 80 kpsi for tight firing pin holes? Where do you think SAAMI pressure levels come from? 270 was SAAMI registered a long time ago 65kpsi. That is too high. So the same large Boxer Mauser case head for the 260 was registered more recently at 62kpsi. These days I have been thinking that the 1889 Mauser case head design, when built with a large Boxer primer and shot in a strong rifle is good for 62kpsi sustained. That would include 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 25-06, 260 Rem, 6.5x55 [US brass], 270, 7mm-08, 7x57mm, 280, 308, 30-06, 8x57mm, 338F, 358, and 35W. This means that I am exceeding the SAAMI limit for 8mm and shying away from the SAAMI limit on 270. The 1950 designed .222 case head with small rifle primer as used in the .222 and .223 is SAAMI rated for 50 kpsi and 55 kpsi respectively. I think this is good for ~72 kpsi in a strong rifle, so I am exceeding the SAAMI registered max average pressure on this one. As was stated by someone else in this thread years ago, the 45/70 brass may be good for 80 kpsi in a Handi rifle, but my shoulder can't take the 28 kpsi loads. What does it all mean? SAAMI max pressure registration levels are not good enough for me. Measuring psi is not good enough for me. | |||
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 I see onefunzr2 has gone to his strength - name calling. He does that when he is mad because he is wrong.The very first post in this thread is all about CHE & PRE "results". The CHE portion even answers a question raised by onefunzr2. And even with ALL THE MONEY he has totally wasted trying to buy his way around Pressure, his M43 won't explain to him what those results explain. Not even if the M43 had been hooked to the Chamber in a Lab environment. ----- Hey Bobby, I see you selectively Cherry Picked, out of context pieces from Dr. Oehler's responses. What did Dr. Oehler have to say about the routine Pressure Variation of the Haphazard SGS??? Was it +/- 1kpsi, +/- 4kpsi, +/- 8kpsi, or even +/- 12kpsi. What validity does that give to psi values, that people outside a Lab Environment, routinely flaunt around various Boards?  Without looking back, I believe I said something to the effect that we probably agreed on more than we disagreed on. ----- Two last questions for Bobby; How many M43s do you think Dr. Oehler decided to sell to anyone, outside a Lab Environment, since shortly after that discussion? Why do you think that is so? ----- Hey Ghubert, I'm interested in a Safe MAX Load which is a balance of Velocity and Accuracy at the Safe MAX Load level for a specific Cartridge. I want long Case Life and the ability to shoot my firearms without being concerned at all about Cumulative Metal Fatigue. I do not want a 300WinMag running at 30-30 Velocities for my Hunting, I want the 300WinMag at it's full potential. Tnekkcc has a great interest in shortening Cumulative Metal Fatigue to simply Metal Fatigue. Understanding his interest in Destructive Testing is a routine Engineering discipline that eludes the thinking of some folks. However, that dosen't mean he isn't also interested in Safe MAX Loads for his normal Hunting Loads. If it was possible, outside a Lab Environment, it would be one additional "useful" tool for us Reloaders. However, Dr. Oehler has made it very clear the Haphazard SGS is misleading at best and potentially disasterous in the hands of someone who does not understand the limitations. As anyone can clearly see in this thread, there are a number of M43 owners who really don't understand what the device is telling them in it's non-calibrated, guessed at dimension and fudge factored state. Ghubert, if you want to try an interesting experiment, try measuring the double-tapered, sloped "Chamber Wall Thickness" in a rifle to 0.0001" accuracy, 0.001" accuracy, or even 0.01" accuracy without using a CMM. And of course since the M43 owners think Micrometers are worthless, you can't use them either. The only thing left is a yard stick, 12" ruler and a set of 0.001" Calipers. Since they can't figure out how to use a Micrometer, obviously anything they measure with a Caliper is a joke. So, how do you think the Haphazard SGS owners outside a Lab, get a good, useful, accurate Chamber Wall Thickness measurement? How do they Calibrate the Haphazard SGS outside a Lab? What Fudge Factor do they enter to compensate for a "partially" glued-on Strain Gauge and guessed at dimensions? How does the firearm look after the Strain Gauge falls off a few times? Once they go through whatever they think is "good enough", what faith would you have in their Haphazard SGS info???  Or, would you prefer knowing when the Load combination has reached a Pressure Level that it is beginning to deform the weakest link in the Firing Sequence - the Case - so you can achieve a Safe MAX Load, including Wildcats? Or being able to reach a Safe MAX Load on older Low Pressure Cartridges, where ANY Case Head Expansion is too much? And yet, some are still in the dark - pitiful! | |||
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