Which twist rate do I need?

[Buzzsaw]

Which twist rate do I need to shoot the heavier 105, 115 bullets in .243? Rebarreling a 700 SA.
Thanks

 

[rhino]

I would say at least a true 1-8! Not all of them are true twists. I would go with a 1-7.75. I would go with a Bartlien and talk to Frank and tell him what you want and he would steer you right. Send it to him or Alan Warner and you'll have a tack driver.

RHINOUT!

 

[Rob01]

Yup true 8 or faster. I have a Schneider 7.5 twist and it handles the 115s great.

 

[Chuckhunter]

Buzz, My 243 Ackley has a nine twist and handles the 107 Sierra's with no problem but I think the 115's would require an 8 Twist. I think a 7 twist may be a little overkill, simply because the 243 pushes those heavy bullets out the tube with some authority.

 

[Buzzsaw]

Thanks, I'll call Frank.

I see you guys sneaking over here from the HIDE.

 

[Obtunded]

Twist rate is based on what length of bullet you are going to use, not the weight.

Twist = 150 X D2/L

Where:
D = bullet diameter in inches
L= bullet length in inches
150 = a constant

 

[Dubya]

Hey Obtunded,
I am terrible at math, could you give me an example of your formula using the following numbers;
Bullet length= 1.367 in.
Bullet Dia. =.2635 in.

Thank you for helping an old geezer who has no education in Math.
Gary.

 

[Obtunded]

Sure...

.2635 X .2635 = .06943225

X 150 = 10.4148375

Divided by 1.367 = 7.62

so to round it off, a twist of 1:7.5" would be optimal.

Cheers,

Ian