Characterization of Particle Output From a Percussion Primer

Report No. ARL-TR-4188
Authors: Lang-Mann Chang; Anthony W. Williams
Date/Pages: August 2007; 24 pages
Abstract: Measurements were made for the percentage of combustion products in condensed phases from a no. 41 percussion primer, and the influence of the condensed phases on the charge ignition in the 5.56-mm ammunition was characterized. The studies were carried out in three phases using three different test fixtures. Results showed 34% of the combustion products in condensed phases, including liquid and solid particles. With the residue remaining in the primer cup added together, the percentage increased to 44%. Subsequently, a channel was developed that was able to capture most of the particles exiting from the primer. Tests were then conducted for primer output flows, with and without particles present, interacting with propellant in a closed chamber. The pressure-time traces for the two flow conditions closely followed each other during the early period of time. At a later time, however, the pressure rise became much faster for the flow with particles present. A correlation of the pressure measurement to photographic evidence suggested that the condensed phases may have helped accelerate the charge ignition process and possibly reduced the ballistic cycle time but had no significant influence on the initiation of charge ignition at the ambient temperature of 21 °C. Further studies will be required to examine the results at cold temperature conditions.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2007