ninehorses
New member
5.56 mm NATO versus .223 Remington
The 5.56 mm NATO and .223 Remington cartridges and chamberings are similar but not identical. Military 5.56×45mm cases are often made thicker and therefore have less case capacity.[17] However, the NATO specification allows a higher chamber pressure. NATO EPVAT test barrels made for 5.56 mm NATO measure chamber pressure at the case mouth, as opposed to the location used by the United States civil standards organization SAAMI. The piezoelectric sensors or transducers NATO and SAAMI use to conduct the actual pressure measurements also differ. This difference in measurement method accounts for upwards of 20,000 psi (140 MPa) difference in pressure measurements. This means the NATO EPVAT maximum service pressure of 430 MPa (62,000 psi) for 5.56 mm NATO, is reduced by SAAMI to 55,000 psi (380 MPa) for .223 Remington.[18] In contrast to SAAMI, the other main civil standards organization C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56 mm NATO.
http://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO
This whole article is an intresting read, sorry the link won't work. So they measure it differently, and I'm confused as to why! Seems that most are too. I think the last line says it all, CatShooter is right.... I think.
Sorry to the OP for getting off topic.
The 5.56 mm NATO and .223 Remington cartridges and chamberings are similar but not identical. Military 5.56×45mm cases are often made thicker and therefore have less case capacity.[17] However, the NATO specification allows a higher chamber pressure. NATO EPVAT test barrels made for 5.56 mm NATO measure chamber pressure at the case mouth, as opposed to the location used by the United States civil standards organization SAAMI. The piezoelectric sensors or transducers NATO and SAAMI use to conduct the actual pressure measurements also differ. This difference in measurement method accounts for upwards of 20,000 psi (140 MPa) difference in pressure measurements. This means the NATO EPVAT maximum service pressure of 430 MPa (62,000 psi) for 5.56 mm NATO, is reduced by SAAMI to 55,000 psi (380 MPa) for .223 Remington.[18] In contrast to SAAMI, the other main civil standards organization C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56 mm NATO.
http://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO
This whole article is an intresting read, sorry the link won't work. So they measure it differently, and I'm confused as to why! Seems that most are too. I think the last line says it all, CatShooter is right.... I think.
Sorry to the OP for getting off topic.
Last edited:
