Not shooting 556 in a 223 chamber

What is the actual chamber differences in stock 223 ammo vs 556?

What's the difference in reloaders pushing as hot of loads as they can when reloading 223 vs shooting 556 stock ammo and pressures?

Could you not shoot 556 ammo in a 223 chamber if it didn't show any pressure signs?

A good read on the subject

linky

Thanks for posting....good info....

If anyone can locate actual military specification documents showing 60000+ psi via SCATP testing methods for 5.56 ammo, I would love to see it.

I would like to see that as well RR.

CIP European standards organization does pressure a bit different not just measurement location but in others like max average pressure. Nato/European specs to SAAMI are like apples to oranges, both fruit but different. SAAMI and CIP both specs but different

I think that I have the specs showing 63ooo psi for 5.56, but will have to look when I get back home. This is an actual military US Govt resource manual giving the full dimensions and pressures for all military ammunition and artillery. Now knowing whether or not this is actual real world data is a totally different matter.

Linky II

Took a look at the link and even thought they do spec for 61000 max PSI for high max pressure with variations of anomaly loads not a standard diet which they list as 55k

3.7.1 Measurement by copper-crush cylinder.-The average chamber pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not exceed 52,000 pounds per square inch (PSI). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 58,000 PSI.

3.7.2 Measurement by piezoelectric transducer.-The average chamber pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not exceed 55,000 PSI. The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 61,000 PSI.

Ive seen this one, I believe. But thanks for posting it, and I hope some other folks take the time to look it over.

Yup. I'm sure many will misinterpret that to mean 61000 psi loading data is okay, too...just as CIP and EPVAT specs are abused.

Western Powder data adds to the confusion. They have data for 5.56 that is listed @ 62,350 P.S.I. Data for 223 and 5.56 on pages 28-32.

Linky III

Yep. That one concerns me. I've seen this kind of thing in other places as well, but I have never seen an AUTHORITATIVE document specifying average pressures of 62000 psi as measured by SCATP or SAAMI methods for 5.56 ammo.

It all boils down to the individual chamber. I have a Super 14" Contender that I cannot get close to published 223 data while my 24" 5.56 AR will not show pressure signs with loads beyond those published.

So say I had a 223 break barrel single shot and I had some 556 ammo and shot it. Primers werent completely flat and showed now issues of pressure...its ok to shoot?

I think so, but I'd check to make sure the bullet isn't jammed into the lands before firing it. I'd also make sure the ammo is loaded to genuine specs, too. In other words, 60000 psi is okay if its pressure is measured by CIP or EPVAT methods. Know uour manufacturer, I would say.