Vicarious 44-40 Pressure Testing

[Savvy Jack]

Without current calibration certs, your measurement data is only useful for relative comparative purposes, and not accuracy.

Of course not!

All that said, your test results are informative and useful, and your attention to details laudable. A great job, in other words.

Absolutely, this give us a reasonable estimate to compare factory loads with published handloads and with with components not published...and NOT NECESSARILY INTENDED to create our own Wildcats

[dangitgriff]

That is correct!
If using factory loads as a baseline for reference, all other measurements are perfectly acceptable as long as nothing else in the set-up is changed.
I sometimes have to remind my co-workers about this method. We use some high-end test equipment on occasion, with results submitted to the government.
Good luck, and have fun. Please post a pic of your test set-up if possible.
R/Griff

[Larry Gibson]

"Were the M43 and PTII certified for accuracy by an independent calibration laboratory before use? Without current calibration certs, your measurement data is only useful for relative comparative purposes, and not accuracy. In my field we use uncalibrated test equipment for indication only."

Yes, IF I had only used the raw data they would have been good only for "comparative" purposes. However........

Apparently you have not read the SAAMI manual on how pressure testing is actually done? If you had you would see, from reading my test results post, that I followed the same procedure testing with 2 different factory ammunitions and an exact duplicated load from Lyman's latest manual with a stated psi measurement. I've no idea what your field is but the measurement of psi in a chamber when a cartridge is fired is not exactly a precise measurement as compared to, say, measuring an object to .0001" with a micrometer. There we can "calibrate" the micrometer by actual adjustment. How do you know your powder scale is weighing accurately? You use "certified" weights to check. Were those weights "certified" by an independent laboratory? I doubt it. How do the ammunition manufacturers "calibrate" the pressure test guns they use either CUP, or more commonly now, piezo-transducer and also actual production firearms with strain gauges and Oehler M83s? They use "reference ammunition" of a specifically uniform lot of ammunition with a known pressure as per SAAMI Standards.

The use of the "reference ammunition" does not "calibrate" in the sense that the system is adjusted or corrected. Instead a correction factor (CF) [sometimes called an "offset figure"] is found by testing the "reference ammunition" in the test gun/barrel. The difference between the actual measurement of the instrumentation on the test gun/barrel and the known pressure of the "reference ammunition" is the CF/offset figure. That CF/offset figure is then used to adjust the measured reading "calibrating" it to a reasonably close pressure reading. And yes, even then the data is basically "comparative". That is why, for each cartridge, SAAMI lists 3 acceptable pressure figures; MAP, MPLM and MPSM. You might note in the data sheets posted there is a variation of velocity shot to shot and a variation of pressure shot to shot. We are not measuring exactly the same thing as each shot is different.

Both systems [the PT II and the Oehler m43 PBL] were checked by the manufacturers for accuracy and correct readings. The PT II was sent back to the manufacturer (RSI) last month to be checked out and was found functioning properly. The strain gauges are "certified and come with a "calibration" figure which is entered into the program of each system. Each system also runs a "check" and "calibration" of the system before each test. Then, as well noted in the test results posted, I used "reference ammunition" of known pressure to get a correction factor ("CF") for each system. The measured psi from each system was then "calibrated" using the CF to obtain a psi comparable to the factory or SAAMI psi's. That is how the ammunition manufacturers do it so "when in Rome, I do as the Romans do....."

If Federal says the pressure of the lot of their 165 Premium 308W ammunition is 59,200 psi and the CF psi figures for the PT II and the M43 PBL are 59,600 and 58,900 psi. Not exactly the same but then there is always an acceptable test to test variation which can be upwards of 4,000+ psi as per SAAMI standards for the 308W cartridge. Given the two systems over lapped the factory psi measurement by - 300 psi and + 400 psi I would say they are very close to giving a correct psi measurement according to SAAMI and industry standards. Probably a lot closer to actual psi than looking at primers, using a computer program, measuring case head expansion or guessing by felt recoil.....

[Savvy Jack]

Please post a pic of your test set-up if possible.
R/Griff

This is the PTII system I was using that Larry is now using
https://sites.google.com/view/44winc...ing?authuser=0

If you guys ever get an interest in testing 44-40 loads, by all means I would love to see the results with those certified equipment and certified test ammo. Heck, I'd like to be there

[Larry Gibson]

Of course not!

Absolutely, this give us a reasonable estimate to compare factory loads with published handloads and with with components not published...and NOT NECESSARILY INTENDED to create our own Wildcats

Wildcats have indeed been created very successfully using the Oehler M43 PBL. Rick Jamison developed the Winchester WSM cartridges at his home in Oregon using the Oehler M43 with strain gauges on commercial barrels. He had custom reamers to chamber them made to his specifications. He then did load development measuring the psi and velocities with the M43. The results of his testing and development were used by Winchester to commercially introduce the WSM line of cartridges.

[Larry Gibson]

Here's a couple photos of the M43 PBL set up at the local range. It was bit more complicated with the PT II there along with another laptop but I forgot to take a picture of all that. Will do next test.....

Attachment 269852

Attachment 269853

[Savvy Jack]

Wildcats have indeed been created very successfully using the Oehler M43 PBL. Rick Jamison developed the Winchester WSM cartridges at his home in Oregon using the Oehler M43 with strain gauges on commercial barrels. He had custom reamers to chamber them made to his specifications. He then did load development measuring the psi and velocities with the M43. The results of his testing and development were used by Winchester to commercially introduce the WSM line of cartridges.

Oh thats sweet!!!

So you have the chronograph set up at 10 yards or so? I had mine about 10 feet. Is there a preferance?

[Larry Gibson]

The M43 PBL uses a 4' screen spacing both at the muzzle and with the down range screens. The proof screen is in the middle at 2' from the start and 2' in front of the stop screen. No real preference as with most such screens you want them far enough there is no chance of the muzzle blast giving a false start and you want the start screen to be a consistent distance from the muzzle with every test/set up. Thus with rifles I set the muzzle start screen 15' from the muzzle. With handguns I've been using 10' the last couple years. The down range screens are placed directly in front of the target. That information is then entered into the program as shown in the top left column of the data sheet.

[Savvy Jack]

the m43 pbl uses a 4' screen spacing both at the muzzle and with the down range screens. The proof screen is in the middle at 2' from the start and 2' in front of the stop screen. No real preference as with most such screens you want them far enough there is no chance of the muzzle blast giving a false start and you want the start screen to be a consistent distance from the muzzle with every test/set up. Thus with rifles i set the muzzle start screen 15' from the muzzle. With handguns i've been using 10' the last couple years. The down range screens are placed directly in front of the target. That information is then entered into the program as shown in the top left column of the data sheet.

thanks!!

[Larry Gibson]

The Rick Jamison saga is a sad one. He was one of the better gun writers back in the 80s and 90s. I always enjoyed his articles and have a couple of his books, one on coyote hunting/calling. He went to a lot of personal expense, development and time developing the short magnum concept. He was smart enough to patent the concept prior to approaching Ruger with the concept [the M77 was a favorite of his]. Ruger said they would make the rifles if he could get a major ammunition factory to make the ammunition. He approached Olin who agreed to make the ammunition. However, apparently Olin backed out of the deal as unless Jamison agreed to no royalties and only licensing Olin there would be no deal. That was atypical of the firearms industry who always thought they should get everything developed or invented for nothing. Ruger was the exception as they had agreed to royalties on every rifle chambered in a short magnum cartridge sold but they apparently got left out of the deal by Olin/Winchester also.

Within 1 year of the deal falling through Olin announced the WSM line of cartridges introducing the 300 WSM with Winchester [U.S. Repeating Arms] making the rifles. Jamison sued Olin and won. Unfortunately, the industry including the gun rags made Jamison persona non gratus so his writing career in the firearms field ended. Dr. Oehler was called as an expert witness to attest to validity and accuracy of the M43 PBL system Jamison used and his testing procedure. Apparently the industry was very displeased with his testimony he also almost ended up persona non gratus......

[Savvy Jack]

Apparently the industry was very displeased with his testimony he also almost ended up persona non gratus......

Yeap, I know exactly how he felt! You may not believe the push-back I get/got from most oldtimers that think they know it all when all they know is what they know. I was even forced out of one forum (member since 2007), accused of posting inappropriate data which actually came right out of Lyman's manual...go figure.

[dangitgriff]

Larry, I find this type of testing interesting. You’re speaking my language here. I am a systems/field/test engineer for a major DoD contractor. No, I haven’t delved into the SAAMI literature, but it is now on my radar. I have no doubt from reading your posts here you are checking all the boxes while conducting testing. The set-up is only as accurate as the least accurate/consistent component. The piezo pressure transducers you are using interest me as well. I suspect there are models that offer higher levels of accuracy but cost a lot more than the common man can afford. I think I might chase this rabbit a little further down the hole to satisfy my curiosity.
Meanwhile, please continue to update with findings. This is some good information.
R/Griff

[dtknowles]

My company and our customers require NIST traceable calibrations. That does not mean that our measurements are more accurate just that we can prove our accuracy.

Sometimes absolute accuracy is not required but the ability to identify trends. My Lee hardness tester does not provide absolute accuracy but it will tell me if one alloy is harder than another and about relatively how hard that alloy is.

If I had some calibration standards I could calibrate my Lee hardness tester or my Chrony chronograph. Larry is at least using some standards so I think his pressure measurements are quite accurate, maybe as accurate or more accurate than we see in published handbooks.

Tim

[dangitgriff]

Hey, dt—ever wonder how the cal lab calibrates their cal equipment? And how do they calibrate their calibration standards for the calibration equipment they use to calibrate the calibration lab equipment?
Ad infinitum... a bonafide universal mystery!
—Griff

[Savvy Jack]

Larry is at least using some standards so I think his pressure measurements are quite accurate, maybe as accurate or more accurate than we see in published handbooks.

Tim

This is what people are failing to look at. All most are doing is stopping right at the...."this is not done by pros, so it must not be correct". If I can do it, my lord, anyone with half a brain can do it. There are a few things that need to be consistent.

Not limited to...

1. Consistent handloads. I hand load all of my test cartridges one at a time. Powder dipping, trimming, weighing each load by hand etc. No loading presses. Now if you want to test the differences between your handloads and your press loads, that is always an option.

2. Having a good "control" such as a reliable factory load that you know is a certain psi. If the factory load you are using is 4,000psi (a low pressure cartridge) lower than max, then your results will follow suit.

3. If you input bad data, you will get back bad data

4. Conducting tests at the same basic temperatures. Testing at 32 degrees today and 95 degrees tomorrow might not be a good thing.

5. Making sure the equipment is working properly. Luckily for us, the PTII can be sent back to Jim for a quick check-up. Keeping a lap-top specifically for testing, not hooking it up to the internet, and not allowing updates. Doing what the user can do to keep the test equipment consistent.


I tested modern 44-40 factory cartridges against vintage replicated loads and against Lyman's handloads. Trying to best replicate actual components used. The best "control" I could find was Buffalo Bores "Heavy" that claimed to produce less than SAAMI map. Thus I set it at SAAMI MPLM.

My results are fairly consistent though not expected to be perfect. It was enough to fill in all the blanks I had.

Attachment 269900
Attachment 269901
Attachment 269902

I know most folks don't like to click external links but here is the link to all 83 of my documented tests using the PTII that Larry now has.

(powder tabs at bottom of window)
https://docs.google.com/spreadsheets...#gid=651705900

[Larry Gibson]

Hey, dt—ever wonder how the cal lab calibrates their cal equipment? And how do they calibrate their calibration standards for the calibration equipment they use to calibrate the calibration lab equipment?
Ad infinitum... a bonafide universal mystery!
—Griff

Also might note that at the Bureau of Weights and measures there is no "pound per square inch" of pressure to use or to "calibrate" firearm chamber pressure testing equipment to.

All methods of measuring chamber pressures are of a secondary measurement method [measuring the effect the pressure has on something else] and then computing/converting that effect into "psi".

[Larry Gibson]

This is what people are failing to look at. All most are doing is stopping right at the...."this is not done by pros, so it must not be correct". If I can do it, my lord, anyone with half a brain can do it. There are a few things that need to be consistent.

Not limited to...

1. Consistent handloads. I hand load all of my test cartridges one at a time. Powder dipping, trimming, weighing each load by hand etc. No loading presses. Now if you want to test the differences between your handloads and your press loads, that is always an option.

2. Having a good "control" such as a reliable factory load that you know is a certain psi. If the factory load you are using is 4,000psi (a low pressure cartridge) lower than max, then your results will follow suit.

3. If you input bad data, you will get back bad data

4. Conducting tests at the same basic temperatures. Testing at 32 degrees today and 95 degrees tomorrow might not be a good thing.

5. Making sure the equipment is working properly. Luckily for us, the PTII can be sent back to Jim for a quick check-up. Keeping a lap-top specifically for testing, not hooking it up to the internet, and not allowing updates. Doing what the user can do to keep the test equipment consistent.

There certainly are a lot of misconceptions regarding the ability to properly test firearms particularly as to calibration and testing in a "lab". Seems many, if not most, don't understand that factory and manual listed pressures apply only to the firearm or test gun they used. Those pressures are not necessarily what that same ammunition will generate in other firearms. Many, if not most, also believe all factory ammunition is loaded to the max safe level (the SAAMI MAP these days) and that all maximum listed loads in manuals are at that MAP level also. Those are false assumptions.

Many, if not most, believe/think all factory/manual pressure/velocity testing is done in a "lab". They aren't. Those tests are conducted on ranges. They may be indoor or out door ranges. Lyman used to do their testing on a 50 yard out door range. As Savvy mentioned, testing should be done at close to the same temperature but newer programs take the temperatures into consideration. Both the M43 PBL and the PT II require temperature, barometric pressure and humidity input. More importantly than the ambient temperature during the test is the ambient temperature of the ammunition. It is not difficult to control the ambient temperature of the ammunition even with the higher temperatures at the range when I test. The idea that a "lab" is needed is a false assumption.

As I and Savvy have mentioned numerous times both systems were tested at the manufacturer for accuracy. The gauges come with a "calibration" factor that is entered into the program and used for calculation. Also the use of reference ammunition is exactly what SAAMI does. Reference ammunition fired in Winchesters test gun will, no doubt, give a different pressure reading than the same ammunition fired in Remington's pressure gun or federals or anyone else's. That's why the "offset figure' or "correction factor" is used. It is a false assumption to think all the tests guns in all the different test facilities ("labs") will give the same pressure reading is a false assumption.

[faraim]

Gentlemen, Thank you so much for the great information. It's going to take me awhile to digest it all! The .44-40 is my favorite cartridge to reload and play with. Although I'll admit to a torrid affair with the .38-40 that I just can't shake! The Rick Jamison saga was a sad story, although I believe I've seen his work recently. I don't buy the gun mags anymore, sites like this are where the interesting info lies. Keep up the good work!