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This is an argument that was kicked around about 4 decades ago when the .270 vs the 30-06 pressures were discussed. A long dead rag writer argued that the .270 brass must be stronger because it was loaded hotter by the factories. He never considered that low number Springfields and 95 Winchesters existed in 30-06. It would make no sense for a factory to try to have two different blank cases for the two rounds. Same goes for the 7X57, 8X57, 6mm Rem and .257 Roberts. Why have 4 different blank cases with the chance of crossing them up in production and putting 6MM Rem loads in brass that was supposed to be intentionally weaker for a 7X57. I suspect the real weakling chambered for the 7X57 was the Remington Rolling. While nor really weak a blown primer in an RRB will blow the hammer back and let the action open right in front of your face. | |||
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Young's Moulus for steel 1. If you check Young's modulus for steels it does not have a huge range for the entire gamut of steels. So the variation is not a bad as eye balling primers. 2. If you work up a good load in a rifle that proves itself safe after a lot of shooting it does give a reasonable comparison or base load to compare subsequent loads to with a transducer. 3. If you are looking for accuracy to ± 500 psi you are out of luck due to the total variation of all the components involved especially new brass. If you get 1 bad case in a lot of 100 you will never know it until you pull the trigger. That is why you should always wear glasses and stay away from near primer blowing loads. For example I got a large lot of 175 Norma 7X57 cases that had been once fired. In that lot was one case that must have been way too soft because the primer pocket is .003 oversize. All the other primer pockets were unexpanded. | |||
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I get tired of these discussions because i always get sucked into them. I am an old reloader with over 36 years of active reloading and shooting. I am a bit conservative with my reloading and I have every gun I ever bought except for the two I gave my kids and one that I returned to the store because it would not hold a group. I get far more than 10 reloads from all the calibers that I reload and shoot. I don't come close to "maximum" loads in any of my rifle rounds. I do get half MOA groups on targets and can guarantee that I hit within an inch of where I aim when I hunt. I load my guns for the accuracy that I expect from them. I don't care what the pressure is or what the velocity is (except for calculating ballistics). If anyone is happy with the accuracy they get, and they aren't too close to me when they fire, I couldn't care less what they load their rifle or pistol to. When the guy next to me at the range was banging his 44 mag cartridges out of his Ruger Blackhawk after spraying them down range, I just moved down to the other side of the next beam and let him shoot. It just shouldn't matter how another guy loads his ammo. As long as he doesn't put anyone else in danger or recommend that load to someone else its all good. I'm walking away now so I don't see any flaming, OK? Speer, Sierra, Lyman, Hornady, Hodgdon have reliable reloading data. You won't find it on so and so's web page. | |||
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Apart from those unexplainable pressure spikes when measuring pressure, the margin of safety is also there for other reasons that may creep in in over time, like: 1. Changes in powder from lot to lot. 2. Switching from one brand of primer to another, even tough it is in the same class. 3. Differing bullet diameters of various brands or even within a given brand. 4. Cartridge cases differ from one brand to another (e.g. PMP vs Winchester) 5. Temperature changes, exposure to direct sunlight, especially in a vehicle standing in the sun. Of course one could argue that none of these things should happen, but the fact is these things do happen. Here is an excellent example ... Someone I know developed a load in a .450 Majoor in Pretoria, which was fine at the range. The next day he travelled to Nelspruit (Lowveld at lower altitude and with a higher ambient temperature) and did a demonstration there. With the first shot the bolt got stuck. This is what happens when one borders at the top end for that extra velocity that is considered so precious - it catches you by surprise. When one goes buffalo hunting in the Zambezi Valley where it gets to 40 degrees C and you load at say 20 degrees C, you can expect some trouble if you border on max loads. Simply put, all high pressure guns loaded to max suffer the same fate, as being closer to the position where the brass gets stuck. Warrior | |||
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I don't understand the above. My 9.3 x 62 is a short barrel 21" rifle and is what we call here locally a 'bakkie' rifle (now you'll understand why it's a short barrel). Up here in Botswana, Namibia and far northern parts of RSA bordering these areas, day temperatures easily rise to 42 - 45° C midday during summer and in the 'bakkie' even a lot higher. The load I'm using has been described on this forum as a hot load - 59gr S335 yielding a MV of 2630fps with GSCHV 230gr bullets, yet no signs of pressure ever detected - even when the rifle is used in these high temperature conditions. I reload at night, no time during the day, at temperatures of roughly not higher than 25° C. Why don't I get a stuck bolt under these high temperature conditions, rifle covered in dust from driving around and a so-called hot load? | |||
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Alf, Thanks for this info. Based on this info, I calculated the following operating velocities based on "working muzzle energy" limit of 2,290 foot pounds: Bullet Weight ----- MV ---------- Energy 175 gr --------- 2,427 fps ---- 2,289.5 Ft-Lbs 160 gr --------- 2,538 fps ---- 2,289.1 Ft-Lbs 150 gr --------- 2,621 fps ---- 2,288.7 Ft-Lbs 140 gr --------- 2,713 fps ---- 2,288.7 Ft-Lbs 130 gr --------- 2,816 fps ---- 2,289.6 Ft-Lbs This makes a lot more sense to me now - at least a common approach is adopted throughout all the weights. Warrior | |||
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Hey Warrior I look forward to see how you dodge this lot again. Not giving a reply and pretending the questons are not there is as good a dodge as any hey? | |||
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Alf, now I don't understand all this even less  Warrior wrote on another thread:
So he thought my 2630fps was about equal to lab test's 2723fps which he said:
Now you say:
So which is which now?  | |||
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I wonder how CIP arrived at this assumption? Energy is based on the square of the velocity. The slope of the pressure/time curve can be varied by changing powder or the amount of powder. I can't see how they could ever make an assumption of linearity except at very small charge increments. | |||
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Holy shit.....wait until Hot Core reads this!!!! /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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Gecko, it's not when or at what temp. you reload, but it's when you TRY your reload. IE Reload anytime, TEST in the heat, OR keep pressures down in cool testing conditions, allowing for shooting when hot. | |||
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Hey Vapo, I saw that and the other thread where "barrel length changes pressure". Sent links to a couple of buddies and when the phone connects you hear a lot of  It only gets me Fired-Up when the Rookies and Beginners would actually believe it. Not much chance for that happening in either of these situations as even they would know better. I'd suggest common logic is working to Gecko's advantage. Once it triggers his internal  switch, he should be OK. | |||
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Alf said:
No I don't, but my hunting friend does!
We are hunting in the same high temperature conditions, both never had stuck bolts or any signs of excessive pressure like flat primers or damaged brass cases of any sort. Both you and Warrior think that this velocity is over the top pressure wise. However, we don't see it. Hot Core, when you say:
I think both me and my friend must agree, the longer barrel had no excessive pressure with the same load same bullet either and we know we are OK  Hot Core, on second thoughts, what then - if not pressure - caused the higher velocity in the longer barrel of my friend's rifle? | |||
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 For those that understand a smidgeon of integral calculus.....the velocity is far more a factor of the area under the pressure-time curve of the duration of the bullet in the barrel than it is of the chamber pressure. Or in other words.....one will reach better velocities by creating 45,000 PSI in the chamber and keeping the pressure at that point during the time the bullet in in the barrel than by raising the chamber pressure to 75,000 PSI with a powder that burns so fast that the pressure drops dramatically after the bullet has traveled a few inches. Raising pressures in and of itself does not equal an increase in velocity. This is the reason one must never allow a chronoghaph reading be the judge of the pressure of the round......they are different things. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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Hey Gecko, Vapo nailed it with an excellent post. Read it a couple of times. Rather than goober up what Vapo posted, let me give you two examples that most folks can understand. The Increase in Velocity is because of good old dv/dt(the change(d = Delta) in Velocity over a specific change in Time, as we all learned in school and that is what Vapo mentioned. You are correct that Pressure is involved, but it is real simple. The looooooonger barrel allows the Pressure(under the Pressure Curve) to push on the Bullet for a looooooonger period of time, which creates more Acceleration. Nothing at all complex about that. ----- Now for the Red Neck version. Your battery is down on your truck and won't start. It is setting on a flat road and you have Bubbetta(your Sweet-E-Pie girlfriend) slide behind the wheel. She holds the Clutch in, puts it in 2nd gear and turns the Ignition on. "You" will be Push Starting the Truck. Push #1. Everything is ready to go and you push to your Peak Pressure, roll the Truck 12', quit pushing, and the Truck EDIT IN: "HAD ALREADY" Accelerated to 4mph. Bubbetta dumps the clutch, the Truck bucks and jumps, but there is not enough Velocity to crank the engine. An angry Bubbetta rants and raves about "you always stopping short of getting the job done properly" and you suspect she is not talking about Truck Pushing. Push #2. You pop a top on a cool one and down it.  Then you ease up to the window and tell Bubbetta to fasten her seatbelt because you plan to get her REALLLLLY going(so to speak). She gets ready and hollers to let`er rip. You begin pushing and hit the same Peak Pressure as before - but - you continue pushing past the previous 12' distance. Your Peak Pressure begins falling off, but you are still pushing the truck and it continues to Accelerate - faster and faster. At 25' you fall on your face(you are no longer Pushing or creating Acceleration). The Truck Velocity is now significantly higher at 10mph. Bubbetta dumps the clutch, the truck starts and she dives by hollering for you to jump in - which you do. Bubbetta rewards you when you get home, but WARNS you to get that job done "properly" for a change - also.  ----- The looooooonger barrel allows the Pressure to push on the Bullet for a looooooonger period of time. The Pressure is Falling Off, but it continues the Acceleration. This results in more Velocity than the shorter barrel because the Falling Pressure has more time to Push. Nothing at all complex about that. And the looooooonger Barrel does "NOT" increase the Peak Pressure. ----- Now go back and re-re-read what Vapo said. | |||
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Hot Core, In your truck story a lot of extra 'pressure' or force was added in the second time around to get that truck pass the 12 feet mark it reached in the first attempt. It surprises me that you of all people didn't realize it the moment you wrote that BS story.  To the contrary, Gecko's friend's longer barrel rifle had not a single bit of new or extra energy added in the process of achieving a higher velocity. What else can we then say other than the fact that the existing force was used more effectively in the longer barrel? The question to be answered still remains did this more efficient usage of force in the process caused higher pressure or not? Gecko and his friend say no, nothing that they can see, but are they right or wrong? OWLS My Africa, with which I will never be able to live without! | |||
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Gerard, Your above post says a lot! But how does the following (last sentence) fits in with your maximum velocity ceilings on your load data webpages?
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Alf you raised my interest explain please.  Doug Humbarger NRA Life member Tonkin Gulf Yacht Club 72'73. Yankee Station Try to look unimportant. Your enemy might be low on ammo. | |||
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Hot Core and Alf are actually quite wrong with their opinions of pressure measuring systems whether used on the range or in a "lab". "The problem with the GSGS system lies in what it actually measures or not. It does not measure absolute pressure..." None of the industry used systems do that, not even CUP. CHE and PRE do not either. They all measure something the actual pressure reacts on. It is then correlated to determine the pressure. Most current inductry pressure systems measure absolute pressure and the time pressure curve from ignition (actually a certainlevel of pressure above that) to bullet exit from the barrel. The industry and he military use different systems. As to standards of calibration....against what and whose "standards? CHE only measures what the pressure has done to that particular case. Where do you get the calibration standards for the lot of cases you are using? You don't, so you don't really have any idea of what the pressure is. With strain guages you do. Theye are calibrated when made. There is no such thing as "calibration ammunition" for the industry regardless of how often Hot Core repeats the lie. The use of strain guage pressure measurement can give you a wealth of information that CHE or guestimation can not. Hot Core continues to spout BS simply because he has made his claim with CHE. He's going to defend it to the end. That's ok but we have moved on. At one time CHE was good to use along with other indicators if you were pushing loads up to the maximum level. However, we now have the ability to measure pressures in our own firearms. Time to move on to more reliable and precise methods that give us much more information. I know what the pressures of my loads are in my 7x57. Hot Core is only guessing. I'd advise others to stick with loads that are found in manuals or factory recommendations for the rifle type you have. Larry Gibson | |||
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I'm all ears (and eyes). Please tell me what system you use and roughly how it works. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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Hey folks, I've been doing pretty good staying out of name calling and wallowing in the mud with the trash on the Board for a good while now. But, I really don't appreciate being refered to as a Lier. So, I'll share an observation with everyone. It seems when some people really do not have a clue concerning what that are blathering about, they get frustrated and begin calling people they do not know Liers. These same people would be the first sniveling yellow cowards to run off crying for their Mamas if they accidentally said such irresponsible ignorance to a real man where he could get ahold of them. I really prefer to remain out of the name calling though, since it accomplishes nothing of value.
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Larry, It seems a safer bet rather than to ignore them and follow the Maverick system proposed here on AR of loading up till you have case failure and then back off somewhat. Please share your load/loads iro your 7x57 mm with us. It would be interesting to see where you are sitting relative to the reloading manuals. Also tell us your barrel length and make of rifle. Thanks Warrior | |||
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Rick, Thanks for the heads up on my misprint, of .005 to .007 as it should have had an additional zero on each..I fixed it.. I load the heck out of my 7x57 with H-414, but I also have a 06 length box and a very long throat so that I can seat a 175 gr. Nosler or Hornady out to half way to the cannalure or about .284 deep in the case. I will not say how much H414 I use as some might be aghast!! but then my gun is set up to duplicate a 7x57 IMP. so to speak, I just did it in a different way..All my guns are good Mausers and Win. M-70 pre 64s. I can get 2900 FPS plus with a 160 gr. Nosler with this set up, and so can any owner of a Brno M-21 or 22 as they are likewise set up. The 7x57 is a mild mannered little rifle, that does about anything most of the larger calibers can do and it does all this with no fuss and no bother and I suspect the real beauty of this little dandy is you can load is mildly and get the same results as loading it hot.. I don't practice what I am preaching here, but the fact is I should..A nice mild soft recoiling caliber that will lay waste to the the masses of critters has a lot of appeal and maybe I will just start doing that and leave the high vel and big bullets to my 06 or 416! Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
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Hot Core Called you a liar? No. I said you repeated the lie. The lie is that CHE tells you the pressure of your load, is safe and is better than any system in use that actually measures pressure in firearms, including test barrels used by arms manufacturers and ammuntion manufacturers. If CHE were that good and reliable then why aren't they using it? The reason is it isn't that good. It seemed like a good idea at the time but was proven deficient. Perhaps you would enlighten us on what methods the arms, ammunition and military use to measure chamber pressures? You want to thump on your chest and grunt an groan and make threats I'll send you my address. Would you send me yours? I doubt it as you probably still live with "mama". As for "remaining out of the name calling business" you do a damn poor job of it. Larry Gibson | |||
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Vapo, You are correct about the area under the curve. that is why I asked the question that no one answered. How can CIP make any ssumption of linearity about the velocity VS pressure. There is no direct relationship between pressure and velocity except at very small increments. You could not compare a load of Unique to a load of 4350 in a 7X57 using the CIP assumption stated above. | |||
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Vapodog I use an Oehler M43. It uses a strain gauge attached to the barrel over the chamber. The strain gauge measure the chamber pressure indirectly by observing the strain or "stretch" of the exterior of the barrel. Chamber and barrel exterior dimensions are used along with the modulas of elasticity to convert observed strain to apparent chamber pressure. The other accepted methods of measuring pressure are; the conformal piezoelectric transducer, the gas piezoelectric transducer located at the case mouth, the gas piezoelectric transducer used with drilled cartridge case, the copper crusher used with drilled cartridge case and the copper crusher used with undrilled cases. These methods of measuring cartridge pressure are accepted by some and not others. For example; the conformal piezoelectric transducer is used and recognized by SAAMI but not by the U.S. Government, NATO or CIP. Who is the unequivocal authority on what one psi is? Is it the "inch" locked in a vault in Europe, Britain or the U.S.? Whose is absolute? If one method says the pressure is 50,750 and the other says the pressure is 51,100 which is right. How is the calibration calibrated? As Dr. Oehler mentions we still don't know a way to measure chamber pressure with absolute accuracy. The use of the M43 with strain gauge provides pressure readings quite consistent with the other methods used. General those are within +/- a few percent. On a pressure reading of 50,000 for instance a 3% difference is +/- 1,500. Since pressures are generally rounded off in manuals and factory charts in a minimum of 1,000 the results are well within accepted variations. The piezoelectric transducers and the strain gauges also give the time pressure curve along with peak preassure. The copper crusher methods only give peak pressure. BTW; CHE is not an accepted method used by anyone in the firearms or ammunition industry either in the U.S. or any where else. Che is nothing more than an abrieviated method of the copper crusher method using an undrilled case. It simply uses the existing case head as the "copper piston" that gets crushed. It also does not provide for the tarage table of the case to accurately measure the pressure required to cause expansion. It is only assumed that so much pressure causes so much expansion. Larry Gibson | |||
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Warrior I'm not putting you off only asking for a few days to post the info you've asked for. I don't have access to my records where I'm at. I will by the end of the week. I can tell you that the info was obtained in a new condition M95 Loewe Chilean Mauser that was sporterized. The barrel is now 22". I'll post information for 139, 150 and 175 gr bullets. Larry Gibson | |||
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SpringTrap, The danger associated with blindly using a chrono and associating the speed with pressure is that, at the same speed, two different powders can give widely differing pressure levels. One may be safe and the other not. You will see we place the "do not exceed" speeds on our website in relation to specific powders and often the "do not exceed" speeds differ, within a caliber/bullet combination, for different powders. The bottom line is that chrono use is common amongst reloaders and pressure testing equipment is not. Neither is perfect, so we must make do as best we can with what is available and use it intelligently in the individual situation. Powder characteristics change over time so published load data revision must also be done from time to time. I am doing that at the moment but it is a slow process. | |||
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Yes folks, that is the same non-calibrated, guessed at dimensions and fudge factored Haphazard Strain Gauge System that I discussed with Dr. Oehler. The link to that discussion is back on page one of this thread. As Dr. Oehler said, it is designed for use in a Lab Environment. The HUGE difference is in the Lab, they can actually calibrate the System which the suckers who buy one for home use can't do. They can also measure the Chamber/Barrel dimensions accurately because they have access to Precision Measuring Devices which are also Calibrated to National Standards. This reduces the Fudge Factor considerably. Those are indeed used by the Manufacturing Industry. Of course, their cost and Destructive Testing Methods make them totally unsuitable for anyone outside the Powder, Bullet and Firearm Industry. Facts like these are Smoke Screens which instill enough Irrelevant but Accurate Information into a discussion in an attempt to hide the actual point of the discussion. As I scan through the rest of the post, most of it is simply useless blather, so I'll skip past it.
 This is another Classic figment of a hopeful and wild (totally ignorant of the facts) imagination.Dr. Oehler mentioned in the link that the normal Home Haphazard Strain Gauge . Having read a few of larry's posts, it would not surprise me to find his Variance is +/- 15Kpsi.And WRONG as usual. If anyone cares to look in the Speer Manuals, they will see that CHE is still in use by the folks who can afford ANY type of Testing Devices. If you have Speer Manual #13, it is on page 53. And once you read through their explaination, you can flip through the Cartridges and see where they have used CHE and are still using CHE. I perfer PRE to CHE because PRE works on every Cartridge ever made. On some of the very old Cartridges at low SAAMI Pressures, you can't use CHE because by the time you can measure any Expansion, you are beyond the SAAMI Pressure Limit. However, PRE still works great, as it always has and always will. | |||
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Hot Core, I don't know you from Adam, but from your above post, which only one person called you on, I wonder where you get your information from. Certainly not High School Physics classses. Your post, from which the above quote was taken was total BS IMHO. Peter. Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong; | |||
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Hey Peter, You are correct. It should have read, "quit pushing, and the Truck had already accelerated to 4mph"... Nice catch. ----- Just looked at another post above and spotted another mistake. Obviously in too big of a hurry. Thanks for the catch Peter. | |||
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Hot Core You're killin' us here....my sides are aching......please stop..... So you're saying Speer uses CHE in the development of their loads. Hmmm...seems strange, some years back I was at their factory and observed a rather sophisticated pressure measuring system. No mention of CHE by the ballisticians. And BTW; Hornady used to have it in their manual too. Then they found, just like the rest of us Speer included, that it just wasn't reliable. Not that I'm saying Speer or Hornady made any false claims (they actually were the closest to chronographed velocities out of actual firearms) regarding velocities but have you noticed how factory published velocities and velocities in some manuals have gotten real the last few years. It's the result of the chronograph being available. To easy to call BS on false readings. Speaking of false readings been using CHE lately.....oh gawd I gotta quit laughing....... Back in the '70s and '80s before chronographs were generally available I gave many a magnum owner major sad faces when they saw what their pet magnum really wasn't doing with factory ammo or many times their reloads, same with many other cartridges. They all said pretty much the same as you're saying; can't be, the technology is bad, uncalibrated, etc. ad nauseum. Time proved them wrong and most of them probably own chronographs now. Same will happen with you, CHE will go the way of Edsel; here for a while, looked real good at the time but just didn't pan out. Keep up the comments though, it just adds to your lack of credibility. Larry Gibson | |||
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Holy Shit HotCore, I do believe that you are the first guy on AR who has admitted that he made a mistake. Most people just delete their post! Good job! Peter. Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth always, even if it leads to your death. Safeguard the helpless and do no wrong; | |||
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