Twist Rate

[TenMetrePeter]

A HMR travels at 2150 + FPS with a 17 grain bullet.
A 223 will travel 3000 FPS with a 40 grain bullet.
Just in case you was board
Centre fire twist rates vary from 1in 8 to 1 in 12

BBF

270,000 rpm
Thats insane!

[tonyc]

You needed feet per minute. Everyone gets it wrong.

Length of pellet is only a factor in that a longer pellet is heavier therefore slower at 12ftlb

I don’t have the gyro formula for mass and angular velocity but I wouldn’t mind betting the faster spin has more stability.

Discuss.

(Can’t you sleep either? )

I think you may find the moment resulting from larger diameter and mass of the .22 may offset the higher spin rate of the .177. It's too many years since I did any moment of inertia calculations - and I don't recall anything to do with gyros - so I'll leave others to sort this out!