right twist rate
- Thread starter Austin
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Longer, heavier bullets have to spin faster,more rpm) to have enough gyroscopic stability in flight. Otherwise they can tip over and wobble as they fly through the air.
When a bullet isn't spinning fast enough, accuracy becomes very bad and the bullet can "key-hole" as it hits the target. This means instead of going straight through from tip to tail, the bullet impacts partially broadside.
1:8 means one full revolution of the rifling in 8" of bore length. This is "faster twist" than a 1:9, which has one full revolution of rifling in 9" of bore.
NOTE however, the rpm imparted to a bullet,as it passes through the rifling) is a function of BOTH twist rate and the speed with which the bullet zips through the bore. This means that you can get by with a "slower" twist rate, if you drive the bullet faster.
For a .260, to shoot the 139-142 gr bullets, we recommend a true 1 in 8" twist. For a 6.5-284, which launches the same bullets faster, you can get by with a 1 in 8.5" twist. Some guys use a 1 in 9" twist, but that can get marginal with the heaviest bullets.
When a bullet isn't spinning fast enough, accuracy becomes very bad and the bullet can "key-hole" as it hits the target. This means instead of going straight through from tip to tail, the bullet impacts partially broadside.
1:8 means one full revolution of the rifling in 8" of bore length. This is "faster twist" than a 1:9, which has one full revolution of rifling in 9" of bore.
NOTE however, the rpm imparted to a bullet,as it passes through the rifling) is a function of BOTH twist rate and the speed with which the bullet zips through the bore. This means that you can get by with a "slower" twist rate, if you drive the bullet faster.
For a .260, to shoot the 139-142 gr bullets, we recommend a true 1 in 8" twist. For a 6.5-284, which launches the same bullets faster, you can get by with a 1 in 8.5" twist. Some guys use a 1 in 9" twist, but that can get marginal with the heaviest bullets.
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