Subject heading says it all... is a 1:8 twist barrel too fast for 40 grain projectiles? I'm thinking of trying some Nosler BT but I've read in some places on the net that you need 1:10 or slower twist to get max. velocity out of them. Is this correct?

One can get 40 grain bullets to stabilize in a 1-14" twist.......a 1-8" twist will only cause one to expend more energy in RPMs and detract somewhat from velocity.

The detraction is minor however but if the rpms are too much the bullets will blow up on their way to the target.

If your goal is to shoot 40 grains then a 1-12" is fine....if you already have the 1-8" then try it and see how it works!

The velocity may suffer slightly, but Nosler Ballistic Tips will not disintegrate - even at 4000 fps. I have a 1 in 9 twist .223 that shoots them very well at about 3500 fps.

I have come to believe that there is no such thing (within limits) as rifling that is too fast. I have fired Sierra 158 gr JHC pistol bullets at 2500+ with a 1:10 twist with sub-caliber accuracy. (.333 groups at 100 yards)
How fast do you have to spin a top to "over-stabilize" it? You can spin a bullet as fast as you want until it fragments from the internal forces but you should be able to maintain accuracy up to that point of destruction.

Paul,
THanks for the info. However, I was more concerned with not being able to achieve max. velocity due to pressure issues and bullets leaving the end of the barrel then shredding due to excessive gyro. forces than I was with any "overstabilization" problems... like you, I've come to the conclusion that you can't really "overstabilize" a bullet.

quote:

Originally posted by PaulS:
I have come to believe that there is no such thing (within limits) as rifling that is too fast. I have fired Sierra 158 gr JHC pistol bullets at 2500+ with a 1:10 twist with sub-caliber accuracy. (.333 groups at 100 yards)
How fast do you have to spin a top to "over-stabilize" it? You can spin a bullet as fast as you want until it fragments from the internal forces but you should be able to maintain accuracy up to that point of destruction.

Your findings are interesting and certainly worth taking note of! Especially as I am looking into re-barrelling my hornet to something faster and therefore have the same question!

It has been said on these forums that over spinning (not over stabilizing) can be detrimental to accuracy due to imperfections in the bullet - the faster it spins the more the imperfections show up. Over-stabilizing, on the other hand will prevent the bullet from 'nosing' into its trajectory arc, resulting in poor long-range accuracy. (They have big words to describe the effects . So, a longer bullet that requires a faster twist will also have the length to overcome the gyroscopic forces that tend to keep it parallel to the line of bore, allowing it to more closely travel parallel to its actual flight path.

I have a fast twist barrel that use to be on a 223, but it was taken off and rechambered to a 22.250, and it has a one in 7 twist....

Any 40 grain bullet that I have shot in it, even at 22.250 velocities, it has been able to take the RPMs generated....

so in a one in 8 twist 223, you will be just fine...

the bullets to look out for with a fast twist, are the Sierra Blitzs and the Hornady SPSX's...
they won't take the fast twists....they will disintegrate about 10 to 15 feet out of the barrel, unless your MV is dramatically reduced...