Re: military surplus 7.62
Posted: Tue Feb 02, 2010 9:15 pm
Found a copy on the Al Gore web. I had to OCR it, so please excuse any typos. What follows is the page from the latest revision that describes the pressure specs for the 7.62x51...
MIL-C-46931F(AR)
3.7.1 Chamber pressure. The chamber pressure measurement shall be performed by either the copper-crush cylinder or EPVAT test method. However, the test method employed shall be recorded on the test results.
3.7.1.1 Chamber pressure measurement at 70 F by copper- crush cylinder test method. The average chamber pressure of the sample cartridges conditioned at 70 F shall not exceed 50,000 pounds per square inch (psi). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 55,000 psi. The chamber pressure of an individual sample cartridge shall not exceed 55,000 psi.
3.7.1.2 Chamber pressure measurement at 70 F by EPVAT test method. The average chamber pressure of the sample cartridges conditioned at 70 F shall not exceed 365 MegaPascals (MPa) (52,940 psi). The average chamber pressure plus three standard deviations of the chamber pressure shall not exceed 400 MPa (58,016 psi). The chamber pressure of an individual sample cartridge shall not exceed 400 MPa (58,016 psi).
3.7.1.3 Chamber pressure measurement at 125 F and -65 F by copper-crush cylinder test. The average chamber pressure of the sample cartridges subjected to 125 F and -65 F storage conditions shall not exceed 55,000 psi nor vary by more than plus (+) 7,500 psi or minus (-) 15,000 psi from the average chamber pressure of the sample cartridges of the same lot tested for the requirements of 3.7.1.1.
3.7.1.4 Chamber pressure measurement at 125 F and -65 F by EPVAT test method. The average chamber pressure of the sample cartridges subjected to 125 F and -65 F storage conditions shall not exceed 400 MPa (58,016 psi) nor vary by more than plus (+)50 MPa (7,252 psi) or minus (-)100 MPa (14,504 psi) from the average chamber pressure of the sample cartridges of the same lot tested for the requirements of 3.7.1.2.
3.7.1.5 Velocity. The average velocity of the sample cartridge conditioned at 70 F, shall be 2,750 feet per second (ft/sec) plus or minus 30 ft/sec at 78 feet from the muzzle of the weapon. The standard deviation of the velocities shall not exceed 32 ft/sec.
MIL-C-46931F(AR)
3.7.1 Chamber pressure. The chamber pressure measurement shall be performed by either the copper-crush cylinder or EPVAT test method. However, the test method employed shall be recorded on the test results.
3.7.1.1 Chamber pressure measurement at 70 F by copper- crush cylinder test method. The average chamber pressure of the sample cartridges conditioned at 70 F shall not exceed 50,000 pounds per square inch (psi). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 55,000 psi. The chamber pressure of an individual sample cartridge shall not exceed 55,000 psi.
3.7.1.2 Chamber pressure measurement at 70 F by EPVAT test method. The average chamber pressure of the sample cartridges conditioned at 70 F shall not exceed 365 MegaPascals (MPa) (52,940 psi). The average chamber pressure plus three standard deviations of the chamber pressure shall not exceed 400 MPa (58,016 psi). The chamber pressure of an individual sample cartridge shall not exceed 400 MPa (58,016 psi).
3.7.1.3 Chamber pressure measurement at 125 F and -65 F by copper-crush cylinder test. The average chamber pressure of the sample cartridges subjected to 125 F and -65 F storage conditions shall not exceed 55,000 psi nor vary by more than plus (+) 7,500 psi or minus (-) 15,000 psi from the average chamber pressure of the sample cartridges of the same lot tested for the requirements of 3.7.1.1.
3.7.1.4 Chamber pressure measurement at 125 F and -65 F by EPVAT test method. The average chamber pressure of the sample cartridges subjected to 125 F and -65 F storage conditions shall not exceed 400 MPa (58,016 psi) nor vary by more than plus (+)50 MPa (7,252 psi) or minus (-)100 MPa (14,504 psi) from the average chamber pressure of the sample cartridges of the same lot tested for the requirements of 3.7.1.2.
3.7.1.5 Velocity. The average velocity of the sample cartridge conditioned at 70 F, shall be 2,750 feet per second (ft/sec) plus or minus 30 ft/sec at 78 feet from the muzzle of the weapon. The standard deviation of the velocities shall not exceed 32 ft/sec.