A method on the macroscopic length scale is developed to determine frictional energy losses between a homogeneous solid bullet and a twisted barrel. This accounts for the entire interaction between the bullet and the barrel surface, the drag due to the engraving forces, and possible friction-optimized bullet coatings. The method applied is based on the shot’s energy balance which requires as input parameters the bullet and barrel geometries, stress–strain curves of bullet and casing material, and muzzle velocity. The validation is done for a .22lr cartridge fired in a small bore match rifle. Additionally, the model is capable to give an average, system-specific coefficient of friction according to Amontons’ law, which could be an essential quantity for the tribological internal ballistics analysis, especially in the future development of lead-free bullets.
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This work was funded by the Austrian COMET-Program (Project K2, XTribology, No. 849109) and carried out at the “Excellence Centre of Tribology” in cooperation with the Armament and Defence Technology Agency of the Austrian Armed Forces.
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Sequard-Base, J., Haas, R., Tomastik, C. et al. Barrel Friction in Sport Rifles. Tribol Lett 66, 3 (2018). https://doi.org/10.1007/s11249-017-0951-4
- Barrel friction
- Energy balance
- Coefficient of friction
- Sport rifle
- Internal ballistics