Springfiueld Armory NHS, US NPS
CASE 71: Internal Ballistics
Internal Ballistics
While some tests studied the hitting power of the gun, powder, and bullet as a complete unit, others examined the interaction of individual components of the weapon, a science known as internal ballistics. Gun barrels had to be built to withstand the tremendous pressures created in them by the burning of the gun powder, especially the new, more powerful propellants.
The pressure was measured by placing gauges over small holes drilled into the barrel. It was important often to know not only the pressure at the breech but also at points along the length of the barrel. Several gauges would be used in these cases.
Mann Accuracy Barrel SPAR3728 This barrel is as close to being perfectly accurate as it was possible to achieve. It is used to test the performance of ammunition. Rounds are fired under conditions of controlled temperature, pressure, humidity, and wind. If the ammunition is consistent and the bullet perfect, each round would hit the same point on the target. The Mann barrel was used in testing the T65E5 cartridge, which became the standard NATO round.
U.S. “Trapdoor” Rifle M1873 SPAR3757 An early example of an internal pressure testing device is this M1873 Trapdoor with a Rodman gauge. It is believed that this rifle and gauge were exhibited at the Centennial Exhibition in 1876.
Pressure Test .30-06 Caliber Cartridge SPAR3747 The pressure created by firing a .30-06 cartridge was measured at two points in this test barrel.
Pressure Test M1903 Action SPAR3734 The internal ballistics of the .224 cartridge were measured at two points in this test device.
Pressure Test .22 Caliber Cartridge SPAR3738 Between World Wars I and II Springfield Armory helped finance itself by offering support services to civilian gun companies. One example of this aid was tests of .22 caliber ammunition using this test barrel.
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