Velocity and pressure effects on projectiles due to variation of ignition parameters

Abstract

The effect of varying the point of ignition of the powder charge within a cartridge case was investigated with respect to both pressure and velocity. By installing a small tube in the base of the cartridge case it was possible to transfer the primer flash to the forward part of the case. Ignition of the powder charge at the top instead of the base gave lower chamber pressures by as much as 6,300 psi and increased muzzle velocity by 35 ft/s. When additional powder was added to obtain the same chamber pressure as a conventionally primed cartridge, muzzle velocities increased by 50 ft/s. When the pressure was brought up past the original level, but kept within normally accepted limits for the 7.62mm NATO round, velocities increased by 100 ft/s over the original load. In order to shape the pressure curve, different loading schemes were tested. Various amounts of powders and powders of different burning rates were layered within the same case, the slowest burning powder being ignited first. Lcwer pressures and flatter pressure peaks were realized from these configurations. The chamber pressure was reduced by 6,000 psi and the muzzle velocity increased by 100 ft/s.