smokeless powders. Most rifle propellants compress between 15 and 22% at 3320 psi, which is about average for initial bullet movement. Further testing by McPherson and Smalley (unpublished) has shown that ignition of propellant in cartridges does not extend beyond 0.5 to 0.6 inches beyond the compressed surface described above. This occurs because the interstitial gaps between the propellant granules are reduced or partially closed at pressure and pyrotechnic gas quickly looses heat to the igniting propellant surface.

Tests and Results are Described Hereafter
An inert propellant simulant was obtained from the Nexplo division of Bofors Munitions in Sweden. This material was designed to have the same mechanical properties and heating characteristics as their normal smokeless powders. A primed 45-70 case was filled with this simulant and a lead bullet was seated over it. The cartridge was then fired and bullet movement into the barrel measured. Upon disassembly the inert simulant was carefully removed and examined. It was welded together to a depth of 0.5 inches from the primer flash hole and soot was noted on the granule surfaces where exposed. Scratches were noted in the soot deposited on the brass inside surface, verifying normal propellant compression and movement. Sectioned brass cases fired with regular propellants also exhibit these scratches. This test was then repeated but 5 grains less simulant was used and 5 grains of normal propellant was added on top of the inert material. Primer ignition did not result in ignition of the live propellant as it was still present at disassembly, and bullet displacement was the same as with the all-inert load. The