[woodguru]

Read up on twist rates for .223's. There is enough weight differentials between the lighter bullets and heavier ones that there is also a range of twist rates that stabilize different weights in an optimum fashion. Twists have been made in quite an extreme range, I think from 1:7 to about 1:14. Yaw or bullet instability is possible if that's what you are looking for, for most bullet instability goes against what you are looking for with accuracy. I was and will be researching this because I want a .243 AR style rifle that shoots very accurate and stable out to 600 yards, I'll get the right twist and load accordingly.

Twist rate is actually a very interesting factor, certain good rifle cartridges have had their potential popularity sabotaged because rifle manufacturers chose the wrong twist rate for production rifles which then impaired performance for logical uses of the cartridge.

This subject actually goes into the question raised here on "rifle or cartridge" which makes the most difference. The twist rate a manufacturer decides to use makes a huge difference in how the cartridge will perform in different weights.