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J. Sequard-Base, R. Haas, C. Tomastik, A. Vernes, F. Franek:
"Barrel Friction in Sport Rifles";
Tribology Letters, 60 (2017), 1 - 10.

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.

Barrel friction · Energy balance · Coefficient of friction · .22lr · Sport rifle · Internal ballistics