Does Polishing a Rifle Bore Reduce Bullet Drag?
Research rept. 1 Jan 2009-31 Dec 2010
AIR FORCE ACADEMY COLORADO SPRINGS CO
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The experiment reported in this article addresses whether polishing a rifle bore reduces the aerodynamic drag of bullets. It was hypothesized that by polishing a rifle bore the aerodynamic drag of bullets would be reduced because a smoother bore would result in smoother rifling marks and thus lower drag. A Remington 700 5R Mil-Spec chambered in 300 Winchester Magnum was used. The bullets used were a 155.5 grain Berger Fullbore Boat Tail and a 125 grain Nosler Ballistic Tip with near and far velocities measured with chronographs at 15 and 315 feet. G1 and G7 ballistic coefficients were calculated using the JBM online ballistics calculator including environmental conditions measured with a Kestrel 4500 Pocket Weather Tracker. These measurements did not support the hypothesis in fact, the velocity losses were greater over the 300 foot chronograph separation and the ballistic coefficients were smaller after polishing the rifle bore. This suggests that polishing the rifle bore actually increased resulting aerodynamic drag on the bullets
- Fluid Mechanics