twist rate of 6.5x47L? why?

[BryanWang]

by using this formula: 180xdiameterxdiameter/twist=bullet length, I calculated that for 6.5 bullet, 9" twist will stabilize bullet up to 1.39" long. that covers almost all the match bullets currently offered. berger website also stats that 9" twist will stabilize heaviest 6.5 bullet they offer.

However, I was reading on 6mmbr.com
this
http://www.6mmbr.com/gunweek072.html
and
http://www.6mmbr.com/gunweek079.html

in the articles, both writers used pretty light bullet(around 120gr) and they all used 8" twist barrel. why don't they use slower twist suitable for light bullets for ultimate accuracy?

 

[Darrell jones]

6.5 x 47 Lapua twist rate

I used a 8 twist because that is what I already had in a 6.5. If I was going to do it again, I would require a 9 twist and shoot the 120 grain range,

Darrell

 

[BryanWang]

thanks Darrell, that encourages me to try the 9 twist!

how long is the free bore would you use for 120gr bullets?

 

[pbike]

BryanWang,

I have recently taken up F class and continue with Score Benchrest. There are two groups of Shooters in F-class as far as I can see.

*Benchresters wanting to take it to the ground

*high power guys wanting to use scopes and bipods

Things I have noticed...

*High power guys don't want to go against what works and into new area.

*Benchrest guys will do anything as long as they can still use a Bag and front rest.

*Longest bullet in caliber worked for me in High power, must be needed for F-class. Even though I never tried a shorter bullet.

*David Tubb doesn't do it so why should we.

*Winchester brass holds more powder, must be best.


What I am getting at is even my closest friends are affraid of Flat base bullets, or slower twist.

I am trying new things all around, and they all seem to be working for me. Try what you want, the 6.5mmx47 Lapua was built around a 123 grain bullet, but that isn't the only bullet in the class.

Paul