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Thread: [B]Load Manual Error......[/B]

  1. #41
    Boolit Grand Master


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    Quote Originally Posted by buckshotshoey View Post
    Can someone explain...in a short paragraph.... how the Oehler M43 detects actual chamber pressure?

    Now I am by no means educated on this subject, but I did find this....

    "I have worked with RSI on this unit's development and personally use it--and it is VERY neat. Unlike the old (and no longer available) Oehler M43 Ballistics Lab pressure unit which attempts to equate the pressures obtained in your gun to what would be obtained by firing that load in a SAAMI specification pressure barrel, PressureTrace gives the actual psi readings generated in your gun--a much more useful measurement. The Oehler readings are higher in most cases than the actual pressures generated in the gun. Oehler apparently included this quirk because their idea was to sell the units to commercial users who could then develop loading data traceable to SAAMI data for liability reasons".

    Is it possible that the Oehler Data is off? And there has been recent reports of Winchester brass with loose primer pockets from the factory. On the other hand, the excess velocity is suspicious. Again, not doubting Larry's findings. I'm not adequately educated enough on measuring chamber pressure to do so. All I can do is ask questions.
    That statement, particularly that in bold, is not true at all. Obviously whoever wrote that is selling/pushing the RSI system. Dr. Oehler's information with the M43 specifically states the measured psi's are relative to the test firearm only. That is the same with pressure test barrels used by ammunition manufacturer's, both CUP and transducer. It is also true of any pressure measurements by the RSI system. They are relevant only to the test barrel unless a "correction factor" is used based on measurement of pressure with "reference ammunition" in that test barrel.

    The pressures the manuals or other sources record and then publish using their their test barrels is most likely not the same pressure the same ammunition will generate in your rifle. Heck, the pressures generated do not even agree test barrel to test barrel. That's why "reference" ammunition is used as measurement standard to get a "correction factor". I also use "reference" ammunition to get a correction factor. I use a specific lot of factory ammunition that a technician provided me the pressure of when it was tested in their peizo-transducer. Thus the difference between the M43 measured psi and the factory measured psi is the "correction factor". That is how it is done to SAAMI test specifications.

    BTW, the RSI system uses the same strain gauges measurements as the Oehler M43 does. The gauge, which is placed over the chamber (I place mine at the SAAMI designated measuring spot), measures the "stress" (electronic impulse) created in the gauge by the pressure placed on the barrel. The computer program then measures the level of stress over the time/pressure curve converting that to psi. Complete information is input into the program including the calibration of the gauge. Dr. Oehler did and extensive test installing on a CUP test rifle 2 separate peizo-transducers, a case mouth transducer, a Gauge for a M83 and a gauge for a M43. That is 6 different pressure measurements for each shot tested. The M83 (a commercial system which is extensively used in the munitions industry) and the M43 gave consistently comparable pressure measurements to the other methods including the CUP method. Keep in mind the CUP method will only measure the peak pressure and does not give any other pressure information.

    Now for the doubting Thomas's please then explain why with the Hodgdon listed max load of 57.5 gr under the 178 gr bullet left 3 of the cases with swollen primer pockets which is a definite sign of excessive pressure in any load manual. The M43 masured that load's psi at 69,000+ which is excessive pressure for any 30-06 in any loading manual and would be certainly in line with swollen primer pockets.

    Of course it's possible the measured data was off the 1st test. However, I checked everything out and had fired a test string of known ammunition performance prior to the 2nd test which gave psi's and velocity in the normal range of ES for that ammunition. Also the reduced loads of H4350 with the same 178 gr bullet produced lower psi's commensurate with the 1st tests results.

    Additionally, I have five different bullets (178 ELD-X, Sierra 175 MK, Hornady 180 SPBT, Sierra 180 SPBT and Speer 180 SP) all loaded over 55.3 gr H4350 which is max Hornady #8 and #10 Manual's charge of H4350 for 175 - 180 gr bullets in the 30-06. The same W_W cases and Federal primers are used as in the previous tests. Also I will test the factory "reference" ammunition (Federal) and the same previous tested ammunition (LC M72 Match). All test strings are 10 shots (SAAMI test standard) unless pressures are excessive and I stop the test. I will test before the week is out, weather permitting, and then we shall see.
    Last edited by Larry Gibson; 10-03-2017 at 03:30 PM.
    Larry Gibson

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  2. #42
    Boolit Master
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    I did not see where anyone doubted your findings. The meat of this thread is that NO loading data should be taken as 100 percent reliable from any source.
    Would you say that I am wrong on my belief or not?
    Many may look at a known source and then say it must be correct because ____________ fill in the blank says so in their data. Sometimes even the very seasoned reloader will do that.
    We need to be careful and not do that.
    We Know Mass Cannot Be Weighed But It Has Newtonian Weight And That Is Derived From Kilograms And Kilograms Can Be Converted to Pounds. But, Still Mass Cannot Be Weighed. But How is the kilograms obtained? Can Kilograms Be Weighed? Evidentally Yes It Can. But, Still Mass Cannot Be Weighed So Kilograms Must Not Exist. Funny Isn't It.
    One good thing out of this the next time I'm at the doctors and they want to weigh me I'll tell them mass cannot be weighed.

  3. #43
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    I was referring to whomever buckshotshoey was quoting.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  4. #44
    Boolit Master
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    Oh, my mistake. I really enjoyed your treatsie on 2400 powder.
    We Know Mass Cannot Be Weighed But It Has Newtonian Weight And That Is Derived From Kilograms And Kilograms Can Be Converted to Pounds. But, Still Mass Cannot Be Weighed. But How is the kilograms obtained? Can Kilograms Be Weighed? Evidentally Yes It Can. But, Still Mass Cannot Be Weighed So Kilograms Must Not Exist. Funny Isn't It.
    One good thing out of this the next time I'm at the doctors and they want to weigh me I'll tell them mass cannot be weighed.

  5. #45
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    Larry, thanks for reporting your findings.
    Last edited by swheeler; 10-04-2017 at 09:19 AM.
    Hell, I was there!

  6. #46
    Boolit Master buckshotshoey's Avatar
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    Quote Originally Posted by Larry Gibson View Post
    I was referring to whomever buckshotshoey was quoting.
    This is where I got it. I just dont have time to research multiple sources. Thanks for the explanation.

    http://www.frfrogspad.com/ballisti.htm

  7. #47
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    Quote Originally Posted by buckshotshoey View Post
    This is where I got it. I just dont have time to research multiple sources. Thanks for the explanation.

    http://www.frfrogspad.com/ballisti.htm
    In my opinion----You do not have the time not to----Some injuries leave debilitating residuals!!
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  8. #48
    Boolit Master buckshotshoey's Avatar
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    Quote Originally Posted by blackthorn View Post
    In my opinion----You do not have the time not to----Some injuries leave debilitating residuals!!
    I meant multiple sources concerning the Oehler 43. I developed loads carefully. That's the reason I frequent this site.....even if it's only for a few minutes at a time.

  9. #49
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    Great post Larry. I would just add one comment:

    Quote Originally Posted by Larry Gibson View Post
    Keep in mind the CUP method will only measure the peak pressure and does not give any other pressure information.
    The CUP method not only doesn't have any "other data", eg a pressure trace and curve, it doesn't actually tell you peak pressure either. It tells you the deformation effects of the average time/pressure and then that is correlated to a value that indicates whether to load is within spec.

    A longer duration, lower pressure pulse can crush the cylinder as much as a shorter duration, higher pressure pulse. The copper pellet may have been exposed to very high pressure, but only extremely briefly. In this case CUP can give a false indication that a load if acceptable when in reality it has pressure spikes that should be a cause for concern. The PE method detects these spikes as well.

    This is one of the reasons you saw certain load data amended down after PE testing became more common.

    The Oehler M43, even with it's limitations, is a huge improvement over CUP, and is as accurate as is needed when used with calibrated pressure barrels. When using on your personal firearms, it will provide excellent reference data for load development.
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  10. #50
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    "The Oehler M43, even with it's limitations, is a huge improvement over CUP, and is as accurate as is needed when used with calibrated pressure barrels. When using on your personal firearms, it will provide excellent reference data for load development."

    Not quite correct; pressure barrels are not "calibrated". The Transducers are calibrated before installation in the pressure barrels.

    Pressure barrels are then, after installation of a calibrated transducer, correlated to each other using "reference" ammunition provided by SAAMI only to members of SAAMI. Reference ammunition is simply a factory lot of ammunition known for its uniform internal ballistics. SAAMI then buys most of it, certifies it as "reference" ammunition and sells it to ammunition manufacturers who are members of SAAMI. By using a specific lot of factory ammunition that exhibits very uniform internal ballistics and knowing what psi it was tested at that lot of ammunition can then be used as "reference" ammunition. That is simply what SAAMI reference ammunition is and is how I check the correlation of my test results to what they should be. As you will see the Federal "reference" ammunition I use is very uniform.

    With the M43 the gauges are calibrated by the manufacturer. That calibration data is entered into the program. I then use a "reference" ammunition to validate and correlate the installation and system. The M43 also goes through a check of the system and gauge before ach test. Also keep in mind even with SAAMI reference ammunition there will always be a variation of velocity and pressure shot to shot. There also will be a variation of velocity and pressure test to test. This is the same as you chronographing and identical load twice back to back and getting two different average velocities, SDs and ESs.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
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  11. #51
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    Well I completed the testing Thursday morning but there was a change to the load. My friend called me saying he needed to apologize because he had given me a bit of misinformation concerning the load that had enlarged the primer pockets in his 06, the subject of this thread. He said that the primer info he inadvertently gave me was not correct. He said he was not using the Federal Match 215s but was, instead, using Federal 210s. Was his bad he said as he uses the 215s I his long range 300 Winchester. He asked if the use of the 215 primer could account for the really high psi’s I measured. ……..

    After I calmed down I told him he could put money on the identical load giving a higher psi with the 215 primers instead of the 210s. In fact it did (more later) to the tune of about 3,000 psi +/-. However, I told him that still doesn’t negate the fact his load of 57.5 gr H4350 under the 178 gr ELD-X bullet with 210 primers was enlarging the primer pockets. I further said that was an obvious indication of over pressure. My bad folks, I should have questioned why he was using a magnum level primer (the 215 Match primers are magnum primers) and probably would have discovered the error sooner. My apologies to all of you but let’s keep in mind that error doesn’t invalidate the previous test data.

    So, I went down to my loading area and pulled 50 bullets, saved the powder, deprimed the 215s out of the cases, re-NS’d the 50 W-W cases, Re-primed the cases with Federal 210s, re-weighed the 55.3 charges of H4350 and then re-seated the 5 different bullets: 178 ELD-Xs, Sierra 175 MKs, Hornady 180 gr SPBTs, Sierra 180 gr SPBTs and 180 gr Speer SPs. With the correct loads and two different factory “reference, loads I departed at O dark thirty for the range, was set up at 0630 and was ready to test as soon as there was sufficient light for the Oehler Skyscreens of the set up M43 PBL to function. The temperature at the range when I began the test at 0645 was 65 degrees. The test loads and reference ammunition had been “stored’ at 70 degrees for 48 hours prior to the test.

    I know some are not aware of SAAMI’s testing procedure and the use of “reference” ammunition. In this test rifle I have used a “lot” of a very uniform load of LC72 M72 Match ammunition. At 65 – 75 deg it invariably gives a 10 shot average of 53 to 55,000 psi and average velocities of 2550 to 2600 fps. To the uninitiated with little experience at pressure testing that may seem to be a large variation but in fact it isn’t. Also used is a test of a 10 shot test using the factory ammunition I use to “calibrate” (a misnomer BTW) the test rife. This was a lot of Federal 150 gr Power-Shok that the Federal technician had given me the tested psi (peizo-transducer) produces a uniform 58,500 to 59,900 psi when tested at 65 – 75 degrees.

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    The first test was the M72 Match. As you can see not only by the data but by the time/pressure traces this lot is very uniform. The muzzle velocity (the M43 makes this correction from the “average”) was 2562 fps with an SD of 10 fps and an ES of 30 fps. That is very good. The Internals also are extremely good with an average psi of 53,500 and on 1,500 psi variation over 10 shots.

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    Next test was with the Federal “reference” ammunition. Again from the internals we see excellent uniformity. Velocity was 2990 fps (box says 2910 fps) the SD at 10 fps and the ES at 27 fps. The average psi was 59,300 with an ES of 2,700 psi…..that also is very good.

    Given the SAAMI MAP for the 30-06 is 60,000 psi (transducer/strain gauge) the Federal load is pretty much top end. I also find the 2990 fps (24” barrel) as top performance also. The measured psi of this test was within 300 psi of the Federal factory measured psi.

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    Next tests were the 5 different bullets listed over 55.3 gr H4350 (the Hornady #8 and #10 Manuals max load for 175 – 180 gr bullets) in fire formed NS’d W-W match prepped case primed with Federal 210 primers. The AOL for all was 3.330”.

    First was the Hornady 178 gr ELD-X. The muzzle velocity was 2758 fps with an SD of 9 and an ES of 27…..excellent. The average psi was 58,800 with 2,800 psi ES. All very well and about 3,000 psi less than the same load with the Fed 215 primers. This load is just under the SAAMI MAP for the 30-06 in this rifle. Obviously, even with the “softer”, 210 primers increasing this load another 2.3 gr would result in considerable over pressure and is why that load previously used expanded the primer pockets.

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    Last edited by Larry Gibson; 10-06-2017 at 11:28 AM.
    Larry Gibson

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  12. #52
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    The next test was with the Sierra 175 gr MK. The velocity was 2732 fps with an SD of 11 fps and an ES of 33 fps. The internals are getting a bit higher than the previous load with the average psi at 53,800 and 3,800 psi ES. That is pretty low psi considering the psi of the previous 178 gr bullet. But something else is amiss here. Look closely at the beginning of the time/pressure traces. Notice how uneven they are. Then go back and look at the M72 traces…..nice and smooth. The M72 is loaded with 4895 which ignites easier at lower psi. Note the Federal trace; see the little “step” in the beginning? That is the bullet leaving the case into the throat/leade which slightly increases case capacity and causes a slight drop or the leveling of psi then the psi picks up and the trace rises smoothly. That is also normal. But back to the traces of the 175 MK load…..those little spikes at the beginning of the trace are not “normal”…..it is telling us something and we shall soon see what.

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    Next test is the Hornady 180 SPBT bullets. The internals are not that bad but then neither was accuracy. The velocity was 2712 fps with an SD of 18 fps and an ES of 59 fps. We see an increase in psi here with the average at 54,50 and an ES of 3,800 psi. Again we’re seeing those little spikes at the beginning of ignition.

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    Next up was the Sierra 180 gr SPBT. This is where those little spikes catch up with us. Notice on the traces 2 through 6 the spikes are pretty pronounced…….the little pressure spikes really were trying to tell me something. Round #7 really got my attention to say the least. Some folks here in the past have questioned my ability to tell when an SEE was imminent……well folks, there it is. Note the delay in ignition (yes there was a very slight “click-bang”), the sharp spike in pressure with a slight stutter….that’s where the bullet was trying to stick in the leade. Fortunately for me and my rifle the bullet started moving and we see the slight drop off in psi and then the rise of psi in a normal fashion as the powder burned normally as the bullet kept moving. Not wanting to push my luck I did not fire the remaining 3 rounds of with the Sierra 180 SPBTs.

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    Well that was certainly fun. A question I immediately wondered; was it really a pre-SEE or did something go wrong with the gauge or system? While the psi was higher than with the Hornady 180 SPBT it still was not excessive pressure at an average of 57,600. As we can also note the ES of the 180 Sierra test was considerably higher at 6,600 psi for the 7 shots. Then there was that slight “click-bang”………

    Best to test ammunition of known performance so I let the barrel cool then shot 5 shots of the M72 Match. I omitted the 1st shot as its psi seemed high. However the next 3 shots psi’s were in the same higher end range for that ammunition. The 5th shot dropped back down to the previous psi range earlier tested indicating that the fouling from the H4350 had been overcome. It definitely appears the barrel was fouled from the previous test with H4350. Before testing each string I ran a couple wet patches (Hoppe’s #9) through the bore and then dry patches. The slightly higher psi’s of the first 4 shots is indicative of a fouled barrel with another powder. What is important here though is the smooth ignition and rises of the traces…..obviously nothing was wrong with the gauge or the system.

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    I decided to test the 180 Speer SPs so I let the barrel cool, cleaned it and proceeded. The velocity was 2665 fps with an SD of 15 fps and an ES of 51 fps. The average PSI was 52,700 with an ES of 3,800. Note on the traces rounds 7 and 8 had small pressure spikes during ignition.

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    At the end of this testing here is the conundrum using H4350 in the 30-06 with 175 to 180 gr bullets as I see it:

    The Hodgdon #27 manual lists 57.5 gr as a maximum load with Sierra 180 gr SPBT bullets using WLR primers. By using the WLR primer instead of the Federal 210 as I used the ignition problem may not have been there as the WLR is a stronger primer. However, I measured the 55.3 gr load of H4350 at 57,600 psi. The stronger WLR primer might have bumped that up closer to the SAAMI MAP of 60,000 psi for the 30-06. We know that with a Federal 215 magnum primer that the 55.3 gr load is well above the SAAMI map. It was this 55.3 gr load that gave a near SEE.

    The Speer #14 manual gives 58 gr H4350 as a max load with their various 180 gr bullets. They also used W-W cases with CCI 200 primers. Given the measured 52,700 psi of the 55.3 gr H4350 load with the Speer 180 SP it might be possible to use another 2.8 gr of H4350 and stay at or under the SAAMI MAP but my past experience doubts it.

    The Hornady Manuals #8 and #10 give 55.3 gr H4350 as the max load with their 178 – 180 gr bullets. They used Hornady cases with Federal 210 primers. Given the Hornady cases have a bit less capacity than the W-W cases their psi’s probably would have been slightly higher. What became obvious in testing the 178 ELD-X and the Hornady 180 SPBT is that there can be a great disparity of pressure with an identical load using different bullet of similar weight, even of the same manufacturer. The 178 ELD-X psi was 58,800 and the 180 SPBTs was 54,500 psi. With the ELD-x bullets in Hornady cases with that load I’d guess the psi was very close to the SAAMI 60,000 psi MAP for the 30-06.

    As to the near SEE; were I to use H4350 with 175 – 180 gr bullets in the 30-06 I would drop back to 53.5 gr as a starting load and consider 55.3 gr as a maximum load. I would most certainly use a magnum strength primer. There were no ignition anomalies with the use of the Federal 215 primers in the previous tests.

    So where does that leave you, the reloader without the test equipment I have? My recommendation is to use another flavor of 4350 (IMR or Accurate). If you really need to use H4350 with 175 – 180 gr bullets then use a magnum primer with the start/max loads I suggest. Use a chronograph and with a 22 – 24” barrel stop when the velocity is 2700 fps – 2750 fps with a minimum of 7 shot tests.
    Last edited by Larry Gibson; 10-06-2017 at 01:11 PM.
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  13. #53
    Boolit Master tazman's Avatar
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    This is absolutely wonderful data.
    Thanks for taking the time and supplies to test this and for posting the results.

  14. #54
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    Quote Originally Posted by tazman View Post
    This is absolutely wonderful data.
    Thanks for taking the time and supplies to test this and for posting the results.
    Ditto! Many thanks!
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  15. #55
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    Add my thanks also. Very informative info!
    God Bless, Whisler

  16. #56
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    Thanks Larry for your efforts and the posts. Very interesting to those of us on the outside.
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  17. #57
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    What is S.E.E.? Would it be Standard Error of Estimate?
    Last edited by buckshotshoey; 10-07-2017 at 09:18 AM.

  18. #58
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    Secondary Explosive Effect
    USMC 6638

  19. #59
    Boolit Master buckshotshoey's Avatar
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    Larry.... have you been in contact with Hodgdon yet? They may try to brush you off but it is the best interest of all of us that you do so. Maybe at least they will retest.

  20. #60
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    Quote Originally Posted by oldblinddog View Post
    Secondary Explosive Effect
    Yes, it occurs when ignition of the powder is delayed, the bullet is driven into the leade, throat or bore and sticks there. The powder then ignites and burns but reaches excessive psi before the bullet can get moving again. The result is a kaboom. It is not a good thing to have happen.
    Larry Gibson

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check