I want to quantify friction between a bullet and barrel to test different friction-proofing coatings and treatments.
Is there a controlled test I could do at low speeds in a lab between samples of treated copper and steel that would be theoretically applicable at velocities up to 1000 m/s? I.e., is the dynamic coefficient of friction considered constant between two materials like copper and steel up to speeds of 1000 m/s, or is there a known relationship between speed and friction that would allow extrapolation from lab-measured coefficients? And what lab tests would be suited to measuring that coefficient to high precision?
(I realize that the most obvious way to approach this problem would be empirically: i.e., just shoot the different projectiles and compare the resulting velocities. I have tried that and gotten confusing results that appear to be attributable to the sources of error in internal ballistics: in particular to the fact that different coatings are probably altering the diameter of the projectiles at the micron level, and dimensional changes can overwhelm the changes in friction, which render A-B comparisons invalid.)