Preferred twist rate for .338 NM

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I'm hearing that there is a 340 Gn. match comming out soon. I'm having a .338 Norma Magnum being made and the barrel is going to be 26" w/ 1:9.5 twist. But from what I am hearing the 1:9 will be better for this 340 Gn. match?

I'm really hoping for a good answer on this soon because my barrel could be getting cut right now as far as I know.

Thanks a million Hider's,
MS