USE
OF INTERNAL SHEAR LINES TO PREDICT GUN
CARTRIDGE PRESSURES AS A FUNCTION
OF TIME
By Smalley, 2004
A series of cartridges has been designed and tested using the parametric techniques disclosed in patent #6,523,475 B2. These cartridges are configured to maximize ballistic performance within the capability of existing geometry. They are designated by the bullet diameter, in either English or metric units, and the case volume in grains of water when the case is filled to the neck-shoulder juncture where the bullet base is to be located. The cartridge designation also includes our registered trademark; SMc. A cartridge designation therefore would be; 22/40 SMc™ where 22 is the nominal bullet diameter, 40 is the nominal case volume and SMc defines the cartridge configuration.
These cartridges operate as follows: The pyrotechnic blast from the primer initiation compresses the propellant into the front of the cartridge case. This compression heats the interstitial air trapped between the propellant granules, which transfer heat to the granule surfaces, preparing them for later ignition. The sonic compression wave is focused slightly away from the bullet base so heat loss to the bullet is reduced and bullet movement is retarded. Heat is concentrated in the propellant just behind bullet base to increase burn rate where it would normally be the last to burn.