According to another source, NATO does its pressure measurements at the mouth of the cartridge, as CIP does in Europe. This results in a pressure reading different from our SAAMI method.
Above is not correct. CIP has NEVER measured any pressure at case mouth, with the exception of Rimfire cartridges. (CIP is not only Europe but also some South America)
Nato EPVAT is measuring at case mouth.
CIP and SAAMI are using a gas port (drilled hole) at about 1 inch (SAAMI) from breech face or 25mm (CIP) from breech face.
If the center fire case is shorter, this distance from reech face is shortened.
There is not much difference between 1 inch and 25 mm causing different results.
The maximum average pressure is the same value = 430 MPa (equals 62366 psi)for both Nato EVPAT and CIP.
The SAAMI MAP pressure is set to 55000 psi.
CUP pressures are no longer listed by CIP, because it's no longer allowed to be used.
SAAMI is listing CUP data, because some manufacturers are using vintage equipment. This is no drawback, the CUP and psi data are correlating.
Maybe we will se in some future an equalisation between SAAMI and CIP data for the .223 Rem. I hope so.
