6mmBR Twist Rate


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Savage.250
March 1, 2008, 11:14 PM
I have been reading everything I can about the 6mmBR cartridge and am planning on purchasing a rifle as soon as I can figure out the details. I will probably be getting a Cooper Montana Varminter mostly because they look great and the company stands behind them. (I also became over whelmed when seeing all the choices there are for building a custom.)

Anyways, Coopers come with a 1-14" twist for this caliber. This is so varmint hunters can use lighter bullets at higher speeds. I won't be varmint hunting necessarily but is there a good compromise for twist rates? I want to be able to use loads with 107 grain bullets (for example) to "buck" the wind and have the ability to shoot longer (600 yd.) distances. I would also like to be able to use lighter bullets if I want to try varmint hunting someday. A 1-12" twist is the best I can guess from 6mmBR.com and similar websites.

Right now I will only be punching holes in paper and the farthest I can shoot at home is just over 400 yards. That is my intended distance for the most part.

So should I just "bite-the-bullet" and choose between the 1-14" and lighter bullets or a 1-8" for heavier bullets? Or is there a compromise?

Thanks in advance!

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RugerOldArmy
March 1, 2008, 11:51 PM
You'll need 1:8" to run the 107SMK or the 105 Bergers.

I've got a 1:8" that will still shoot the 75 VMax well, and loves the 80 Gr Berger. It doesn't like the 58 Gr V-Max as much, but I don't know that the issue is the fast twist, I suspect it is more of a barrel preference.

Hit 6mmBr.com there is a lot of good info there for that cartridge. Coopers are great, very sexy, and all I've seen shot well. Be prepared for a slightly heavy trigger tho!

For Varmint hunting, consider the 22 BR. Everything the .22-250 is, but more accurate and uses less powder.

Links:

http://www.6mmbr.com/6mmbr.html
http://www.6mmbr.com/22BR.html
http://www.6mmbr.com/varmint.html

This is really an under-rated cartridge. My favorite.

Seafarer12
March 2, 2008, 12:38 PM
I agree with Oldarmy. 1-8 is the way to go and 6mmbr.com has a lot of good info.

Walkalong
March 2, 2008, 12:55 PM
Benchresters use mainly 62 to 68 Gr bullets in 6PPC. 1-14 is used because it is the slowest twist which will stabilize that weight range at the velocities produced as to be as gentle on the bullets as possible. They are not concerned about heavy bullets. They want the slowest twist that will work. You will need something faster.

rundm
March 4, 2008, 04:53 AM
I have a model 700 that was built up for br shooting and I made the mistake of getting the 1-14 twist. It will stabilize the 75 gr vmax without problems for those pesky prairie dogs and will do an adequate job with the 87's although I do not use it for those. It will definatly not do anything above those. You will need to get a faster twist barrel to shoot the 105's and 107gr bullets. you could probably get away with using a 1-10 twist or something like that and be fine. Pretty much anything a 243 win has would be fine. some people just like to make sure that the barrel twist is kind of matched to the bullets that they will be shooting. You just need to make sure to get the fastest twist necessary to stabilize the heaviest bullet that you will be using. It will still be able to shoot the lower weight bullets without tearing the jackets off as long as you are using good qual bullets like v max's or nosler bt's. you can spin them to absurd rates and not have problems with them. RG

Clark
March 7, 2008, 08:18 PM
For relatively cheaply, I can put a 22" 6mm PPC bull barrel take off onto a Mauser Action and ream it out to 6mmBR.

The problem is the twist rate is 1 in 14".
Your main bullet with will be a 65 gr Vmax.
75 gr Vmax are real iffy for stabilization.


But if the barrel is a 1 in 10" or 1 in 8" and is 26" long, then you may be launching 107 bullets at 3000 fps in 1000 yard competition.


6mmBR is great cartridge:
1) long throat life
2) slow to heat barrel
3) low powder costs


There is a big difference in the 6mmBR value of a Shilen Stainless barrel 26" 1 in 8" twist vs a Shilen Stainless barrel 22" 1 in 14" twist, becuase benchrest guys flood the market with the latter.


What does it all mean?
I can put a short fat 1 in 14" twist premium barrel on a Mauser action in 6mm BR for $100 ~ $150.

A long barreled 1 in 10" twist premium barrel on a Mauser action in 6mmBR will cost me $400 to $450 to put together.

A long barreled 1 in 10" twist premium barrel on a Ruger #1 in 6mm BR will cost me $1000 to $1100 to put together.

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