I guess I am belaboring the point, but you cannot just throw out a maximum case pressure spec without also specifying the protocol by which it is measured. In the last post, the 35,000 psi spec for 9 mm Luger P ammunition and 38,500 psi for +P ammunition is per the SAAMI testing protocol, and the 36,500 psi spec for the NATO load is per the C.I.P. protocol. The SAAMI protocol is used widely in the US, but in most European nations the C.I.P. protocol dominates.
Both SAAMI and C.I.P. use piezo-electric pressure transducers but they use different transducers. More importantly, in the SAAMI protocol, the transducer is inserted into a hole drilled in the test barrel a given distance from the case mouth and that distance varies with different calibers. In the C.I.P. method, the transducer is inserted directly into a drilled case at a distance 25mm from the breech face if the cartridge is long enough to allow. For cartridge cases too short to allow that position, the transducer is positioned in the cartridge case a specified distance from the breech face that again varies with caliber.
Not surprisingly, the two different methods will yield different pressure readings even with exactly the same cartridge loaded the same way in the same test barrel. Sometimes the C.I.P. method yields a pressure less than the SAAMI method and sometimes it yields a greater pressure. For example, in the case of 9 mm Luger and .45 ACP the C.I.P. protocol yields a lower pressure than SAAMI but for .44 Magnum the C.I.P. pressure is greater than SAAMI.
The Pmax for standard pressure 9 mm Luger per the C.I.P. protocol is 34,084 psi. The Pmax for 9x19 mm NATO is 36,500 psi, again by the same protocol, so the Pmax for the NATO load is 2,416 psi. greater than standard pressure. That makes ithe NATO load 7.1% "hotter" per the C.I.P. protocol.
C.I.P. does not to my knowledge set pressure standards for +P ammunition in the way the SAAMI does for some calibers. The pressure standards for standard pressure and +P 9 mm Luger ammunition per the SAAMI protocol are 35,000 and 38,500 psi respectively, making the Pmax for 9 mm +P 10% higher per the SAAMI testing protocol.
Both SAAMI and C.I.P. use piezo-electric pressure transducers but they use different transducers. More importantly, in the SAAMI protocol, the transducer is inserted into a hole drilled in the test barrel a given distance from the case mouth and that distance varies with different calibers. In the C.I.P. method, the transducer is inserted directly into a drilled case at a distance 25mm from the breech face if the cartridge is long enough to allow. For cartridge cases too short to allow that position, the transducer is positioned in the cartridge case a specified distance from the breech face that again varies with caliber.
Not surprisingly, the two different methods will yield different pressure readings even with exactly the same cartridge loaded the same way in the same test barrel. Sometimes the C.I.P. method yields a pressure less than the SAAMI method and sometimes it yields a greater pressure. For example, in the case of 9 mm Luger and .45 ACP the C.I.P. protocol yields a lower pressure than SAAMI but for .44 Magnum the C.I.P. pressure is greater than SAAMI.
The Pmax for standard pressure 9 mm Luger per the C.I.P. protocol is 34,084 psi. The Pmax for 9x19 mm NATO is 36,500 psi, again by the same protocol, so the Pmax for the NATO load is 2,416 psi. greater than standard pressure. That makes ithe NATO load 7.1% "hotter" per the C.I.P. protocol.
C.I.P. does not to my knowledge set pressure standards for +P ammunition in the way the SAAMI does for some calibers. The pressure standards for standard pressure and +P 9 mm Luger ammunition per the SAAMI protocol are 35,000 and 38,500 psi respectively, making the Pmax for 9 mm +P 10% higher per the SAAMI testing protocol.
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