barrel twist

[xander]

I am having a 338 ultra mag built on a Ruger #1 with a 28 in. bbl. I am going to use 200-210 grain bullets.Everyone says I should use a 1-10 twist.I did the Greenhill formula to calculate the twist rate for the bullets I'm planning to use and it comes to 1-12 or a tad slower.I won't be using any bullets over 225 grs. max.I would appreciate some suggestions for those of you that use a 338 UM,particularly those of you that use lighter bullets. thanks.

 

[Guest]

I don't have a 338 RUM but I do have a
338-06 Ai , it has a 1-12 twist and shoots the 200gr Nosler Ballistic tips and 210gr Nosler Partitions great.
My velocity is just over 2500fps out of a 22" barrel , I would think that the faster 338Rum would use maybe a 1-13 but why risk it ? Your not gonna realy gain any velocity by going to that much slower twist.

 

[ZERMEL]

Ruger#1.
Ther Greenhill formular is not all that reliable, it overstabilizes by a considerable margin. You should use a constant of about 180 rather than the 150. I would use a 1-12" twist because of the higher velocity which the Greenhill formula does not address.
The faster the bullet the less twist you need.

 

[xander]

Thanks for the input.I think I will go with the 1-12 twist.This rifle is intended as an open country rifle.I think the lighter bullets will suffice.