Maybe this is a good time to bring up something I have been puzzling over for quite some time. I've looked over a lot of stuff I've been able to locate on-line regarding the differences between 5.56 and .223 Remington. Some of my observations:
- SAAMI limits .223 Rem to 55000 psi
- the US military utilizes a standard they call SCATP, which includes pressure testing identical to the SAAMI method
- the highest published SCATP pressure figure I have found for 5.56 in US Army documents was a touch over 58000 psi, IIRC
My conclusion for the moment is that the highest pressure American 5.56 ammo would register a little over 58000 psi ala SAAMI. I know there is or was a new M855A1 round loaded hot, but as far as I know the pressure spec was never made public. Based on this, I would assume that an AR15 with 5.56 chamber can handle 58000 [SAAMI] psi, no sweat. On the other hand...
- NATO follows a standard they call EPVAT for 5.56 ammo testing
- EPVAT allows pressures of about 62000 psi
- EPVAT pressure measurement is similar to CIP methods, but not identical
- the CIP pressure limit for .223 Remington seems to be about 62000 psi also
Now...maybe my assumption that European .223 Remington ammo would register 55000 psi if tested to SAAMI methods is faulty. I kinda doubt it though. But here's the problem as I see it: published 5.56 data in American loading manuals lists pressures up to 62000 psi. Comparing it to .223 data in the same manual shows the 5.56 data is considerably hotter, so I would assume that the 5.56 data as published would actually mean pressures measured via SAAMI methods (but I never see this specified, IIRC). The thing is, if they're publishing data that would yield 62000 psi when measure ala SAAMI, what would CIP methods show on that same ammo? I think it would be waaaay over 62000 psi.
The whole thing does not smell right to me. Where is the error in my perspective? What am I not seeing?
