maintenanceguy 509 Posted September 28, 2014 I never really thougth about how fast a bullet rotates before. I understood that bullet rotion stabilized the bullet in flight and prevented tumbling but I didn't know how fast a bullet needs to rotate for that to work. I figured the math is pretty simple so I did a couple of calculations and I'm shocked at how fast a bullet really rotates. No wonder rifling stabilizes a bullet. The formula I came up with is: Bullet RPM = 12 / twist rate (in inches) x 60 x muzzel velocity. A few examples that shocked me are: A .22 with a 16" twist rate at 1,000 fps spins at 54,000rpm A .223 with a 9" twist rate at 3,000 fps spins at 180,000 rpm A 9mm with a 10" twist rate at 1,200 fps spins at 86,000 rpm. Quote Share this post Link to post Share on other sites
mark_anthony_78 0 Posted September 28, 2014 Formula seems right, but your results are not: .22 = 12/16 * 60 * 1000 = 45,000 .223 = 12/9 * 60 * 3000 = 240,000 9mm = 12/10 * 60 * 1200 = 86,400 Makes F1 engines seem downright slow... Quote Share this post Link to post Share on other sites
raz-0 1,256 Posted September 29, 2014 Formula seems right, but your results are not: .22 = 12/16 * 60 * 1000 = 45,000 .223 = 12/9 * 60 * 3000 = 240,000 9mm = 12/10 * 60 * 1200 = 86,400 Makes F1 engines seem downright slow... .223 makes a small turbo charger seem slow, which is a feat. Quote Share this post Link to post Share on other sites
mipafox 438 Posted September 29, 2014 .223 makes a small turbo charger seem slow, which is a feat. What is the service life of a .223 in flight? Quote Share this post Link to post Share on other sites
noylj 5 Posted October 5, 2014 MV x (12/twist rate in inches to make one completer revolution) x 60 = Bullet RPM or MV X 720/Twist Rate in inches to make one completer revolution = RPM Quote Share this post Link to post Share on other sites
raz-0 1,256 Posted October 6, 2014 What is the service life of a .223 in flight? A second or two. But that's because it impacts something. LEt your impeller or compressor wheel hit something and see if you get a second or two out of it. Quote Share this post Link to post Share on other sites