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.223 & 5.56MM myths and facts

MK111

"Happy Hunting Grounds in the Sky"
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SW Ohio
http://ballistictools.com/articles/5.56-vs-.223-myths-and-facts.php

In short:
1. 223 & 5.56 MM NATO are both loaded to 55,000 PSI by SAMMI specs.
2. 223 PSI is measured by SAMMI pressure method of using a barrel with a hole drilled in the chamber area and a pressure sensor used to measure the pressure off the brass case.
3. 5.56 MM NATO uses the European CID pressure method of a barrel with a hole drilled through the chamber area and a hole is also drilled through the brass case round so the hot gas puts pressure directly on the sensor. (go figure it's as if no brass case is present when firing a gun)
4. So if you pressure test a .223 or 5.56 MM round with a SAMMI test you would get 55,000 PSI, and that same round pressured tested with the European CID pressure test you would get 62,000 PSI.
5. That's were all this confusion comes from between .223 & 5.56 MM by using different methods but the true pressure results are the same.

6. Believe it or not.

A problem can arise if 5.56 MM is fired in a .223 tight commercial chamber. So it's not so much the ammo that's it's more of the chamber of the rifle that raises the pressure.