High-speed photography at framing rates of up to 1 million per second has been employed to investigate the mechanisms of initiation of an explosion and its propagation in a small arms cartridge. Specially designed models have been used to simulate the conditions inside the cartridge and the photography has been carried out using reflected light. It is found that the impact of the striker pin on the percussion cap of the cartridge causes several reaction sites lying close to the impact axis and it is argued that these sites are located at intergranular frictional hot spots in the primary explosive composition. It is also shown that the reaction from the cap to the main propellant charge is transmitted by the streaming of the hot reaction products of the former into the grains of the latter.
Mohammad Munawar Chaudhri,
"Working of a small arms cartridge", Proc. SPIE 1801, 20th International Congress on High Speed Photography and Photonics, (1 January 1993); doi: 10.1117/12.145736; https://doi.org/10.1117/12.145736