Velocity dependence of barrel friction.

A tribological model is presented that provides a correlation between bullet velocity and friction force in firearms. The model is based on the observation that higher velocities result in lower friction and assumes that the surfaces of the bullet and barrel consist of elastic asperities. The model predicts that as the relative velocity increases, the asperities are less likely to return to their neutral positions. The model was tested using experimental muzzle velocity and gas pressure measurements for caliber 5.56 × 45 bullets and the results were in good agreement with the model predictions. The coefficient of friction obtained with the model is also in line with literature values for very low sliding velocities. [Display omitted] • Quantification of the velocity dependence of barrel friction. • The model is based on a transversal oscillation of asperities in the surfaces. • Verification of the model with experimental data in 5.56 × 45. [ABSTRACT FROM AUTHOR]