Gunsmithing Twist for Heavy 7mm

[GB213]

I am wanting to build a 7mm WSM or 7mm RSAUM to shoot the 180 VLD. Is the 9 twist o.k., or should I go with the 8.5. Any insight would be helpful.

 

[7mmRM]

Re: Twist for Heavy 7mm

1:9 will do just fine.

 

[Bacarrat]

Re: Twist for Heavy 7mm

Most of the people here run 1:9.

If you are running some heavier 190 or 200 gr bullets, you might want to step up to a faster twist.

 

[USMCj]

Re: Twist for Heavy 7mm

Rock Creek recommended 8.7 twist to me.

 

[Graham]

Re: Twist for Heavy 7mm

It depends. Do you shoot in the winter at sea level?

 

[GB213]

Re: Twist for Heavy 7mm

Graham, Yes I am here in Maryland

 

[GB213]

Re: Twist for Heavy 7mm

How long of of barrel do I need to push a 180 @ 2900 - 3000 with a 7mm rsaum?

 

[Graham]

Re: Twist for Heavy 7mm

Go 1 in 9, then.

And it depends on the amount of powder you use.

 

[gme]

Re: Twist for Heavy 7mm

28" will get you there 30" if you don't mind the extra length

 

[USMCj]

Re: Twist for Heavy 7mm

I went with 28. With one setback Ill be at 26" before I need a new tube.

 

[Catzass]

Re: Twist for Heavy 7mm

why the 1:9 at sea level vs. 1:8.7?

 

[Jeffvn]

Re: Twist for Heavy 7mm

I shot a 9 twist when in Houston and it did well with the Berger 180s.

Oh yeah the barrel was 28" long, and got them to 2,900 without difficulty in my 7WSM.

JeffVN

 

[TresMon]

Re: Twist for Heavy 7mm

Catzass

Cold air, as well as air at or below sea level (BSL) will make it harder for your bullet to go to sleep (stabilize) as well as slow your bullet faster which sooner makes it destabilize.