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Old February 3, 2001, 07:24 PM   #1
MFH
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I know that excessivly flattened primers are one of the first caution signs. I thought I recalled that using a micrometer on the pressure ring, an expansion of .0015" greater than that of factory ammunition was considered as an acceptable maximum. Anyone know if this is correct?

MFH
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Old February 3, 2001, 09:25 PM   #2
Southla1
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Well MFH, its lots of things, all taken together. An excessivey flattened primer can mean excessive head space or high pressure or both. Web expansion should be around.0005 or less, not .0015, but then again taken by itself its not a sure indiactor. If you are handloading and have a well flattned primer, a cratered primer, more than .0005 web expansion, sticky extraction, and a load approaching maximmum in a reloading manual BACK OFF. A primer may be flatted because its a soft lot. It may be cratered because of an oversized firing pin hole. Web expansion may be excessive bacause of soft brass in that lot of cases. Stickly extraction may be caused by a rough chamber. These can also be pressure signs. You see many things can cause the signs but if ALL of them or more than one or two occur you are probably getting a lot of pressure.
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Old February 4, 2001, 08:41 AM   #3
Hot Core
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Head Exp vs Pressure Ring Exp

Hey MFH, I agree with Carlyle that getting 0.005" Expansion across the Case Head is about all you want. If it is a new case, and that is the first Load through that case, it can be mis-leading though.

Also, I've not had good luck comparing "before firing and after firing" dimensions out on the Pressure Ring. But, I do use the "after firing" dimensions. I like to establish a Standard using a factory round. Just use the measurement across it's Pressure Ring as something to "compare" your relaods with. "Stop" when your Pressure Ring Expansion is the same as the factory load when reloading those "same" cases.

Depending on the intensity of the actual reloads you put in a case, and the actual temper of the case, how many times you can get "useable data" from those cases varies. For example, using Case Head measuring, I typically get good info on loads 2-6 or so. On the Pressure Ring I get good info on loads 1-9 or so. Always best to be a bit conservative here though. Repeated firings "work harden" the case and will eventually skew the results

I do have a File on Case Expansion I can email to you if you would like it. You will need to have Microsoft "Word" in order to open it and Microsoft "Excel" to open the Load Data Sheet. Just recently updated them with some input from about 5 people. So if you, or anyone else would like a copy, just let me know.

Good hunting and clean 1-shot kills, Hot Core
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Old February 4, 2001, 10:07 AM   #4
Kenneth L. Walters
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Alas I didn't save the bookmark but you can now buy pressure sensing equipment for a couple hundred bucks if that is of any interest.
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Old February 4, 2001, 03:17 PM   #5
Southla1
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Kenneth, isn't that maybe Oehler that you may be speaking of? I do know that they have it, how expensive it is I do not know.
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Old February 4, 2001, 03:28 PM   #6
Kenneth L. Walters
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No it isn't Oehler though he does have something similar. Oehler's approach, if memory serves, requires an IBM compatible portable computer and the investment of some serious money. There is another somewhere on the web who has figured out how to do this for just a couple hundred dollars. Don't know why I pitched the bookmark. Still it couldn't be too hard to find. Sounded both interesting and inexpensive.
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Old February 4, 2001, 04:51 PM   #7
Southla1
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Kenneth I am going to look for that site. If I find it I will send it to you. I would love to have the Oehler but I know how one must pay for quality and Oehler is quality . Now a couple of hundred that I can sneak by .
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Old February 4, 2001, 05:35 PM   #8
jsn
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Peak Pressure meter

is that what your looking for? go here and scroll about half way down the page.


http://www.mcs.net/~sfaber/

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Old February 5, 2001, 12:07 PM   #9
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I observed something the other day that made me rethink the whole "primer observation" system of checking pressure. Lately there's been talk about how the new cheaper Winchester primers have thinner cups. Well I noticed that my brother in laws factory loaded .357 Winchester ammo had SEVERELY flattened primers, compared to the equivalent Remington brass. Both loads were fired in the same gun, both were 125gr JHP loads. I think that the cup thickness is a huge factor in how much flattening you see.
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Old February 5, 2001, 12:12 PM   #10
Bogie
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Disclaimer - I shoot benchrest

Yup. There's a big difference in primers. I shoot with a buncha folks, all shooting roughly the same calibre, and we essentially determine when we're too hot by whether or not we're popping little holes in the primers. Drop the charge about a tenth of a grain, and pray it doesn't warm up anymore. We know that's not the way to do it, but danged if we're not getting the best accuracy at that level...

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Old February 5, 2001, 03:31 PM   #11
Southla1
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Hot Core, if you do not mind please e-mail that file also. I had a lot of loading data on one of our puters in excel and of course that would be naturally the puter that crashed, not the other one that had MS office installed on it
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Old February 5, 2001, 10:20 PM   #12
Hot Core
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Hey Carlyle, I'll get it out to you shortly.

Here is the link someone had mentioned about the "less expensive" Pressure Meter. I don't know beans about it though. http://www.mcs.net/~sfaber

Good hunting and clean 1-shot kills, Hot Core


Hey jsn, I'd hit the "Go to last unread post" button and forgot you had already posted where to find the pressure equipment. Wasn't ignoring your post......Hot Core

[Edited by Hot Core on 02-06-2001 at 09:52 AM]
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