Firearm’s Percussion Ignition System Performance: Influencing Factors and Sensitivity Analysis

Abstract

Normal firing of the percussion ignition system is essential to the reliable operation of firearms. Percussion energy, critical dimension, and assembly parameters all have a significant impact on a firearm’s percussion ignition performance. This study was intended to reveal how various factors influenced a firearm’s percussion ignition performance. The percussion ignition process of a small-caliber automatic rifle was simulated in this paper by conducting pressure measurement tests for the entire cartridge to obtain the gas pressure response. A finite element model was built to study the firearm’s percussion ignition performance. The simulation parameters were calibrated based on experimental results, and the accuracy of the simulation model was verified. Parametric simulation was performed using Isight to assess the firearm’s percussion ignition performance. The following influencing factors were considered: hammer’s falling height, primer seating depth, firing pin protrusion, locking clearance, firing pin head diameter, thickness of primer cup bottom, and anvil head diameter. Local sensitivity analysis was carried out for each influencing factor using the control variable method. Global sensitivity analysis was conducted based on the optimal Latin hypercube design that accounted for coupling effects between the influencing factors. The results showed that firing pin protrusion, primer seating depth, hammer’s falling height, and firing pin head diameter hurt the percussion ignition performance. Locking clearance, thickness of primer cup bottom, and anvil head diameter had a positive impact on the percussion ignition performance. The influencing factors were ranked as follows in descending order of sensitivity: Hammer’s falling height>anvil head diameter>firing pin head diameter>locking clearance>thickness of primer cup bottom>firing pin protrusion>primer seating depth. Our results provide technical support for designing the percussion ignition system of firearms and improving the reliability of percussion ignition.