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.)


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I would think the friction regimes will be very different, especially for something like a gum barrel where the projectile is contained. At high speeds plastic deformation of the surface will be much more significant as well as possible chemical reactions due to the heat/energy. Therefore I wouldn't necessarily expect the coeffcients to be similar.

You could possibly could set up a test rig using a high speed touching a flat plate to test the friction at high speed outside a barrel. However, I haven't thought about the details and this would probably be difficult\expensive\dangerous to set up.

A quick google gives me this paper which supports my theory that friction would not behave consistently.


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