7mm Rem Mag Twist Rate

[Chris71404]

Getting ready to order a carbon 6 barrel for a 7mm rem mag build. Length will be 22-24" (havent decided yet). I want to shoot a slightly heavier bullet 162-170. What twist rate do you all recommend? Was thinking 1:8.5.

 

[wldcat]

8.5 should be good to 180-185 traditional lead bullets, only reason to go faster twist then that would be for heavy mono's. 1:9 would be stable with a 170 vld

 

[MtPockets]

I would go 1:8.
It'll work with cup and core and monos both.

 

[WapitiBob]

An 8 will shoot anything.

 

[Phil Rizzo]

Lower elevation and slower MV can require faster twists…seems better to be safe than sorry.
Id go 8 and sleep easy.
in fact my 7prc and SS are 8tw

 

[Bob Wright]

If I had to rebarrel my 7RM today it would be an 8 twist instead of my 8.5 currently. What I have works good but with limitations on monos and above 180 Bergers. Also, consider the chambering such that you can seat farther out than SAAMI chamberings.

 

[SSG Graybush]

Getting ready to order a carbon 6 barrel for a 7mm rem mag build. Length will be 22-24" (havent decided yet). I want to shoot a slightly heavier bullet 162-170. What twist rate do you all recommend? Was thinking 1:8.5.

I did a 8T 26" and shoot a 180 vld-h at ~2917 fps. Not completely maxed out, H1000, Peterson brass, cci 250. 67 thou jump. I'd do a 7T now though. You could shoot a 160 gr SBD2(.69 g1 bc) at 2900-2950 fps with those shorter barrels, I would think. But the 160 gr SBD2 needs a 7T.

 

[sable tireur]

Before the advent of long for caliber and nonmetallic bullets, factory rifles used the 1:9" for the most part. Here is the short list of factory twist rates:

7mm Remington Magnum - 1 in 9"...HVA; Rem 40-XB, 700 (1969); Magnum Research Mountain Eagle; T/C Rifle
7mm Remington Mag. - 1 in 9-1/4".... Remington 700; Savage 110, 111, 112, 114, 116; Sako; Win 70, 770; Ruger #1, 77 (old); Mossberg; Browning A-Bolt II, BLR 81; Weatherby Mk V
7mm Remington Mag. - 1 in 9-1/2"... Ruger (present); Savage (present)
7mm Remington Mag. - 1 in 10" ....Browning; FN; H&R 300; Interarms Musketeer; Schultz & Larsen; Browning BAR Mk II; Weatherby Vanguard

There are other factors to consider when using short barrels and long, heavy bullets.

Magazine length is important so you don't get caught with one that's too short for your desires. Be sure to check your reamer for the dimensions necessary to achieve your loads.

I shoot a very specialized cartridge in a longer barrel using the Badlands 160 Super BD2 bullets. My twist rate is 1:8" (because that's what I had in the shop) since I shoot this above 2,000' and in warmer temps. When it dips down a little colder, I lose about 8 BC points which I can calculate. It's a one-of-a-kind bullet and shouldn't be the deciding factor in your choice of twist rates unless you want to shoot this bullet only.

Your 1:8.5" is just a tad too slow for some of the majority of the bullets in the weight range you want to use. I suggest the 1:8" from experience.

Enjoy the experience!

 

[MagnumManiac]

If it were me, I'd go with a 8" twist. Then you can shoot any bullet available.

Cheers.

 

[xsn10s]

My new RemArms 700 7mm RM has a 5R 1-8" twist. One of the reasons why I bought it.

 

[sable tireur]

Smart move by the new owners!

 

[xsn10s]

Yes it was. And even though it's an ADL model it has the new Timney Impact trigger.

 

[SSG Graybush]

If it were me, I'd go with a 8" twist. Then you can shoot any bullet available.

Cheers.

Not a 160 SBD2, it needs a 7T.

 

[sable tireur]

The Badlands 160 Super BD2 was already stated as the exception, no need to restate. It's the only bullet requiring a 1:7" twist by a manufacturer.