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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Testing Friction Reduction of Bullet Coatings
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<blockquote data-quote="Michael Courtney" data-source="post: 682416" data-attributes="member: 28191"><p>The velocity difference in the 6.5x284 is small and not attributable to the coating as it was not my intent to do a scientific test and hold all the other factors constant (new vs. fired brass, temperature, degree of bore cleaning, lot of bullets, lot of primers, lot of powder, etc.) The tests in the 5.56mm NATO were scientific and these factors were carefully controlled.</p><p></p><p>Less friction may well increase bore life, but I would not expect a 15% decrease in friction to increase bore life by more than 15%, and I expect the benefit might not even be that much if throat erosion due to the pressure and temperature of the hot gases are the main cause of accuracy degradation at the end of bore life.</p><p></p><p>We have not been able to do a convincing quantitative test of copper fouling to say that any coating decreases fouling. We have discussed with chemists how we might quantify the amount of fouling we pull out after shooting, but the available techniques are prohibitively expensive. </p><p></p><p>On the theoretical side the field of tribology (the science of friction and wear) suggests that wear is not usually reduced disproportionately to friction and that as long as there are high levels of friction, both surfaces will continue to experience wear. The tribology journals and other scientific works suggest that the lubricants under discussion tend to reduce wear in rough proportion to their reduction of friction. </p><p></p><p>On the experience side, we have never failed to pull out copper when cleaning a rifle after shooting coated bullets. Even as few as 10 to 20 bullets produce copper fouling. We cannot even conclude subjectively that the amount of copper seems to be less.</p></blockquote><p></p>
[QUOTE="Michael Courtney, post: 682416, member: 28191"] The velocity difference in the 6.5x284 is small and not attributable to the coating as it was not my intent to do a scientific test and hold all the other factors constant (new vs. fired brass, temperature, degree of bore cleaning, lot of bullets, lot of primers, lot of powder, etc.) The tests in the 5.56mm NATO were scientific and these factors were carefully controlled. Less friction may well increase bore life, but I would not expect a 15% decrease in friction to increase bore life by more than 15%, and I expect the benefit might not even be that much if throat erosion due to the pressure and temperature of the hot gases are the main cause of accuracy degradation at the end of bore life. We have not been able to do a convincing quantitative test of copper fouling to say that any coating decreases fouling. We have discussed with chemists how we might quantify the amount of fouling we pull out after shooting, but the available techniques are prohibitively expensive. On the theoretical side the field of tribology (the science of friction and wear) suggests that wear is not usually reduced disproportionately to friction and that as long as there are high levels of friction, both surfaces will continue to experience wear. The tribology journals and other scientific works suggest that the lubricants under discussion tend to reduce wear in rough proportion to their reduction of friction. On the experience side, we have never failed to pull out copper when cleaning a rifle after shooting coated bullets. Even as few as 10 to 20 bullets produce copper fouling. We cannot even conclude subjectively that the amount of copper seems to be less. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Testing Friction Reduction of Bullet Coatings
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