Obtaining a Correlation between Pressure Test Results of Small Caliber Ammunition According to Different Test Standards

The science of “Internal Ballistics” have extensively studied the pressure generated within the cartridge and clearly indicate that maximum generated pressure (Peak Pressure) is not to exceed the yield strength of the material of which the cartridge case is made of [1]. Failure to ensure this could result in catastrophic accidents that may lead to death or serious injuries. Different test standards (SAAMI, C.I.P, MIL-STD and NATO EPVAT) were established to ensure the safety of the ammunition in terms of pressure. These standards differ in many aspects from the test procedure to the equipment used to the acceptance criteria. The main motive behind this study was understanding the need to establish a scientific correlation between pressure measurements obtained by different test standards in order to save cost, time and effort as well as ensuring that a specific type of ammunition that was pressure tested according to one standard is safe to use in a specific weapon that was tested according to another. The main aim of this study was to investigate the possibility of finding a scientific correlation between the mean peak pressure values obtained by the NATO EPVAT and CIP test standards for 7.62 x 51mm NATO Ball Reference Ammunition through derived and validated equations with fixed conversion factors in order to convert “actual” Mean Peak Pressure (MPP) and Standard Deviation (SD) values obtained by NATO EPVAT test to predict those values in the C.I.P equivalent and calculate the Average Maximum Pressure (Ptmax).Thirty 7.62 x 51mm NATO BALL reference ammo were tested according to NATO EPVAT and C.I.P and the mean peak pressure conversion factor (FMPP) was found to be 0.974, while the standard deviation conversion factor (FSD) was 1.381. Both conversion factors were used to convert the MPP and SD values obtained by EPVAT testing of the reference ammunition, to their C.I.P Equivalent. These C.I.P converted values were then used to calculate (Predict) the Maximum Average Pressure Ptmax which was 3540.26 bar. Validation of this result was achieved by conducting an actual C.I.P pressure test on the same amount of reference ammunition which resulted in a Ptmax of 3422.40 bar with an error percentage between actual and predicted Ptmax of 3.54%.