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Old June 2, 2012, 10:58 AM   #1
steve4102
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SAAMI vs CIP

I'm looking for the actual CIP specs for the 7.62 NATO. I have been to SAAMI's web site and have their info, but I could use a link to the actual CIP data as well.

I am in a heated discussion with a few fellow handloaders that insist that the 7.62 NATO has a MAP of 50,000 psi. I am trying to convince them that the NATO round is 50,000 CUP not psi and I'm loosing ground without the official CIP specs.

Anyone know where I can find this info?

Thanks.

Last edited by Brian Pfleuger; June 2, 2012 at 01:41 PM. Reason: clean up
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Old June 2, 2012, 02:08 PM   #2
243winxb
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M80 NATO 7.62mm ball cartridge- 50,000 PSI

What is "CIP" ? Never mind, found it. http://en.wikipedia.org/wiki/Commiss...Feu_Portatives 50,000 PSI here > http://www.dtic.mil/ndia/2006smallarms/faintich.pdf Could be wrong??

Last edited by 243winxb; June 2, 2012 at 03:04 PM.
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Old June 2, 2012, 05:02 PM   #3
Jimro
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That technical manual describes the loads, not the max pressure by SAAMI specs. Every load has a specified component and max pressure (the latest 300 Win Mag sniper ammo spec'd by NSW Crane upped the max pressure to 68k PSI).

I'd trust someone with Quickload over that manual as to exactly what the max pressure of 46 grains of WC846 behind a 147gr FMJBT lit with a #34 primer. It could very well be 50k psi, but I'm guessing when the Army went from CUP to PSI they just changed labels instead of converting.

Jimro

EDIT: From Hogdon's reloading data, BL-C(2) is the cannister equivalent of WC846, and notice the pressure is measured in CUP not PSI.
150 GR. NOS BT Hodgdon BL-C(2) .308" 2.800"
45.0 2661 40,200 CUP 48.0 2839 50,000 CUP

Now you can't really compare CUP to PSI without a direct measurement, but look at the max loads for these two powders with the same max velocity.

150 GR. NOS BT Hodgdon H4895 .308" 2.800"
43.0 2742 43,200 CUP 45.5 2870 51,000CUP
150 GR. NOS BT IMR IMR 8208 XBR .308" 2.800"
40.0 2604 45,500 PSI 44.5C 2870 60,800 PSI

Now I can't prove it one way or another, but it looks like the TM just changed CUP to PSI at some point.
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Last edited by Jimro; June 2, 2012 at 05:23 PM.
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Old June 2, 2012, 05:10 PM   #4
mehavey
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See:
http://www.24hourcampfire.com/ubbthr...rs#Post5543157

These figures (60,191/CIP and 62,000/SAAMI) agree exactly with Broemel's QuickLoad specs
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Old June 3, 2012, 10:42 PM   #5
Jim Watson
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Quote:
I am in a heated discussion with a few fellow handloaders that insist that the 7.62 NATO has a MAP of 50,000 psi.
The problem is that the US Army is not a member of SAAMI or CIP and for a good number of years specified ammunition on the basis of a crusher gauge calibrated in pounds per square inch, dead load or hydraulic.
They ignored the CUP term coined by SAAMI to distinguish between crusher gauge and piezoelectric transducer readings for a long time. This has led to the common myth that commercial .308 is loaded substantially "hotter" than military 7.62 because the units were given as "psi" for both, although measured differently.
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Old June 4, 2012, 06:58 AM   #6
Bart B.
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Jim Watson's correct. The use of "PSI" back when copper units of pressure (CUP) was the only reliable way of measuring chamber pressure was a big mistake. But back then, folks from ballistic engineers to ordinary consumers didn't know any better because "pressure" was the key word and pressure per square inch was common in the USA for all sorts of things.

Download the following, print pages 16 and 21 then ask them to explain why the CUP and PSI numbers for the .308 Win. are not the same. And if the max pressure's really 50,000 PSI, why are numbers so darned much higher in SAAMI's specs for PSI? The difference between the NATO and commercial version is insignificant.

http://www.saami.org/specifications_...wnload/206.pdf

Here's some other sites with some good info:

http://kwk.us/pressures.html

http://en.wikipedia.org/wiki/CIP_(firearms)

http://en.wikipedia.org/wiki/NATO_EPVAT_testing

http://www.shootingsoftware.com/ftp/psicuparticle2.pdf

Google CIP and check out what shows up.

For those who insist that USA arsenals loading ammo used the PSI system for measuring chamber pressure before about 1970, ask them what company made the transducers to measure them. If they give you a name, ask them how that could be because none were used before then. And finally, ask them to call Lake City Army Ammunition Plant and ask them when they switched over from copper units of pressure to the electronic psi systems.

Last edited by Bart B.; June 4, 2012 at 07:35 AM.
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Old June 4, 2012, 07:44 PM   #7
steve4102
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Thanks everyone.
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