Recommended twist rate for 7mm-08 AI

[Bangarang]

I'm going to re-barrel a Savage Model 12 LRP to 7mm-08 AI for hunting. I have a couple questions.
What twist rate is recommended for 140 to 165 grain bullets?
I'm also thinking the LRP barrel contour is a bit long and heavy for toting around though I've been doing it for several years. What is the minimum contour for satisfactory stiffness?
24" or 26"?
Lastly, any recommendations for chamber and throating specs?
Thanks, B

 

[mcfred]

A 9 twist is common and will stabilize most .284" projectiles 175gr or less, especially at altitude. If you can shoot any lightweight rifle well, then I don't think there's a contour too thin to meet MOA or less accuracy. An extremely light weight barrel will likely affect rifle balance/feel more than accuracy. Of course for long shot strings, it will heat up quickly.

I had a 26" 7mm WSM with a Remington Sporter contour it was ≤MOA for the first 1000 rounds and lightweight. It got very hot, quickly, and I evaporated a lot of the rifling out of it.

The SAAMI spec 7mm-08 chamber appears to have about .135" freebore. I would keep a freebore of .050" or less for the lightweight projectiles, and for heavier projectiles you expect to fit in a 2.875" length magazine box, but a short throat might affect how factory 7mm-08 fit your 7-08AI chamber. I suggest you consult a gunsmith for what works best, or if going with an off-the-shelf prefit, ask about the chamber from the vendor.

 

[Steel head]

I’d go 1-9.
1-8 would be kinda silly for a 7-08.

 

[XTREM HTR16]

Could even do a Bartlein 8.5 twist if you’re unsure

 

[RogueTanker]

1/9 will work with 180s, but 8 twist will definitely be good.

Can't really comment on the contour, but for the chamber think about the brass you'll be using.

I use lake city brass with a thicker neck. Standard brass comes in at .312 and lake city resized comes in at .314-5. I went with a .3185 neck for clearance. Even with thinner brass I haven't had any issues with accuracy it brass life.

Good luck.

 

[XTREM HTR16]

Lapua makes 7mm08 brass. It’s good stuff.

 

[Bangarang]

Thank you all for your great replies!
B