7mm-08 Twist Question

[RedRaider]

I am building a 7mm-08 rifle and need some help with twist rate. I need to say that this will not be a long range rifle. This will be a 100-300 yard rifle with a Brux barrel and Predator action. It will be 21" long with a #6 contour.

I will never shoot a bullet heavier than 140 grains (I have other guns for bigger bullets). I will primarily shoot the Barnes 120 grain ttsx bullets (1.217 inches) and expect to get about 2850fps with the 21" barrel. I might shoot the 140 Barnes ttsx bullets which will be around 1.325 inches in length. Both of these bullets are slightly longer than similar weight bullets from other brands. If I shoot the 140's, I expect 2700 - 2750 fps.

I don't want to spin these bullets to fast and possibly affect accuracy. I also might pick up a little speed (not a lot, but maybe a bit) with a slower twist. I was thinking a 1:9.5 twist for this gun, but as I plug it into calculators (JBM Ballistics), it appears a 1:10 would keep the bullet stabilized (it actually says 1:11 would just barely stabilize the bullet, but not the 140 Barnes).

Anyone out there have some advice for me on this build? It would be greatly appreciated!

 

[Deans]

I have a Ruger MKII 7-08 with 1:9.5 factory twist. I am working up a load with the Barnes 140gr TTSX and getting good accuracy @ 100yds for an Elk hunt. I need to do some tweeking but expect good/excellent accuracy out to 300-400 yds if I do my part. Hope this helps.

Deans