A 338 cal 300 SMK at 2790 FPS has 200,880 rpms in a 10 twist barrel. The 9 twist barrel with the same velocity will have 223,200 rpm. This gives the 9 twist 22,320 more rpm’s.
Still can't follow. How does fps become rpm? Wouldn't you multiply by 60 to get rpm?I can't believe rotations in seconds would remain a constant for a long distance shot.
This is how I did the math before finding that formula.
Went to JBM ballistic found Time of flight over 100 yards for a bullet at 3000 fps which was .103 seconds.
100 yards = 3600 inches which means a bullet fired from a 1 in 10 twist will rotate 360 times during it's travel over a 100 yards.
1 (second) divided by .103 (TOF over 100 yards) = 9.708
360 times 9.708 = 3495 rotations per second
3495 times 60 = 209700 RPM
* I rounded the numbers off.
After thinking about it a bit more I realized why my numbers don't line up with the real smart guys.
