.223 ammo weight and twist rates.

[deldago]

I found a pretty good deal on some Black Hills ammo in different weights to see what the accuracy difference would be and the 68 grain says that a 1 in 10 twist is best for accuracy and that 75 to 77 grain uses a 1 in 8 twist for best accuracy.I haven't seen many ar's with a 1 in 10 twist,is it very common?I have a 1 in 8 twist 18" barrel so their suggestion would be 77 grain bullets.What are your experiences?