I have searched alot of info here but I am still a little hazy on twist rate vs bullet selection. I have a 26 inch barrel on a savage 223 and it should be a 1-9 twist rate. i have read about bullet stabilization with different twist rates. I am just trying to shoot accurately as possible. So what is the equation for twist rate, Is it turns per foot or the like. Does a higher number mena a faster spinning bullet or slower? How do you determine if a heavier bullet or lighter bullet will work best? Sorry for the log question, but i am really trying to make haed or tail out of this info. Thanks in advance.

Twist rate is the number of inches required to make a complete 360-degree rotation.

a 1:9 rate means 1 rotation in 9"
a 1:12 rate means 1 rotation in 12"

In a given caliber, a faster (1:9) is required for bullets of greater length. You will read and hear people talking about bullet weight when referring to twist, but it is really the bullet length that determines twist.

So 1:9 is a faster twist than 1:12 Correct?

that is correct. the lower the number, the faster the twist.

So am I correct in saying faster twist barrels usually like lighter bullets than slower twist barrells.

Just the opposite. A heavier (longer) bullet requires a faster twist to stabilize the bullet than a lighter (shorter) bullet.

The 1 turn in 9" twist barrel will usually shoot the 69 grain .224 bullet more accurately than a 1 turn in 14" twist barrel. But either barrel may shoot the 50 grain 224 bullet just as accurate but you can usually push the bullet faster out of the 1 turn in 14" twist barrel.

Bullets of a given caliber and the same material must be made longer inorder to be made heavier, a longer bullet needs to spin faster to be stabilized in flight. A 9 inch rate is pretty fast and will provide enough spin to stabilize a longer therefore heavier projectile. In my opinion it's better to spin a shorter bullet faster than a longer bullet not fast enough.

quote:

Bullets of a given caliber and the same material must be made longer inorder to be made heavier

Not true...

a 52 grain boat tail .224 bullet is longer than a 53 grain flat base bullet, and technically requires a faster twist

Bullet shape, amount of bearing surface, OAL, and weight all affect what rpm is needed to stabilize a bullet.

So since I have a 26 inch barrell with a 1-9 twist rate i should statistically have better results with 50 grains and up bullets as a general rule of thumb? I should probally steer claer of the lighter bullets.

Train yourself to think bullet length when you consider twist rate, not bullet weight. In a 9" twist .223 barrel, any bullet longer than 0.9" will not do well at times. (Atmospheric conditions play a role here as well)

Around 0.75" bullet length would be a good choice for most hunting conditions and, as the bullet becomes shorter from there, gyroscopic stability increases to the point where the bullet will not shoot well as it bows over the high point of the trajectory.

About halfway down this page there is a bullet length calculator you can download. Take a real bullet, measure it and feed in the numbers.

gunz
You can use the lighter bullets. The question of overstabilization is theory. I have a 1 in 9 twist .223. It will shoot 40 gr to 69 gr bullets just fine. It does have some trouble with the 77gr/80gr bullets.
The only way I think you might see an efffect of overstabilization would be at very long range, maybe.
It is the length that is important but you will see most references to weights.

muck