300 RUM and 230 Hybrid Twist Rate

[Tumbleweed]

10 twist will run Berger's 230s. Sierra's will need a 9

Fortunately I went 9 twist on that build. 10 may stabilize at higher elevations but ballistic coefficients are gonna be compromised in a 10 twist. From what I learned with this rifle and others, my next RUM will be an 8 twist.

 

[Triple BB]

I went with a 9 in my RUM. No issues with the 230's...

 

[couesaddict]

I've got a 10 twist proof on mine and the bc seems to hold true at 3200' for me with the 230 hybrid targets.

 

[VLD Pilot]

Fortunately I went 9 twist on that build. 10 may stabilize at higher elevations but ballistic coefficients are gonna be compromised in a 10 twist. From what I learned with this rifle and others, my next RUM will be an 8 twist.

No doubt the 9 is ideal and an 8.5 would be as well. Many guys that have 10 twist barrels think they need an 8-9 but that's false. Yes, stability isn't full in a 10 as it is an 8.5-9 but it is stable. Keep the 10 twist if it works. If starting with a new barrel, I would go with what Tim recommends or Frank recommends if using a Bartlein.

 

[Tumbleweed]

No doubt the 9 is ideal and an 8.5 would be as well. Many guys that have 10 twist barrels think they need an 8-9 but that's false. Yes, stability isn't full in a 10 as it is an 8.5-9 but it is stable. Keep the 10 twist if it works. If starting with a new barrel, I would go with what Tim recommends or Frank recommends if using a Bartlein.

Will a 10 twist provide sufficient accuracy? Often yes. Will the bullet be fully stabilised? At higher elevation maybe but not at lower elevations. There is a reason Bryan Litz recommends 9 twist or faster. Something too many don't factor in is the loss of b/c at slower than optimum twist rates. 9 twist guarantees at least advertised b/c but an 8 twist can actually improve b/c over advertised. Hornady has done extensive testing on this topic through live firing out to 2000+ yards tracked by Doppler radar.
Moral of the story, if I guy is going to build a rifle for heavy bullets why the hell would you not factor in at least minimum recommended twist or a little faster? Like I said, my next big .30 will be at least 8.5 twist, maybe 8 twist.

 

[VLD Pilot]

I agree 100%+. Just be careful when you say "Big" 30. The bigger the case and faster the twist, the faster the RPMs. Get in touch with Frank Green at Bartlein about optimum twist for your next build. He has a pretty good grasp on that subject. My 9 twist 300 WSM stabilizes and keeps stability very well at 1500 yards with 230s. It's not my optimal 1500+ yard choice but it's very sufficient until wind is gassing. I'd probably go and safely could go to an 8.5 with it and not be too bad RPM wise. Going to say a 30 Nosler or 30/338 Lapua, I'd stick with a 9. That's just my personal choice and I think a good one for the huge case capacity 30s.

 

[Wachsmann]

So everyone that is running the 230's, what is your OAL of your load? In my stock sendero I had to single feed at 3.78 inch for accuracy. This was with retumbo. I am going to try some other powders and see if I can get them so they fit in the stock mag at 3.660 which is the max I can go and get the gun to cycle correctly.

 

[Tumbleweed]

So everyone that is running the 230's, what is your OAL of your load? In my stock sendero I had to single feed at 3.78 inch for accuracy. This was with retumbo. I am going to try some other powders and see if I can get them so they fit in the stock mag at 3.660 which is the max I can go and get the gun to cycle correctly.

Shortening them up to fit in a short little factory magazine box will eat up your case capacity and it's usually a challenge to get them to shoot well there.
I think I was running mine a little over 3.9" single feed but also have a very long, match throat. If you can run them around 3.8" in an extended Wyatt box it's not bad