6BR...fast vs slow twist

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foxbat

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Just a quick question to my esteemed, and learned, colleagues.
I've had good experience with 6BR in the past.
I'm looking at acquiring a new rifle...either factory or semi-custom, and was wondering if I should go with a fast ( 1:8 ) or the slower ( 1:12 ) twist.
I will do the majority of my shooting at 100 and 200 yards, with the possibility of some 300 yards shooting....( Welcome to the wonderful world of Souther Ontario....:rolleyes:)
I welcome suggestions as well as to a source and specific unit, but was leaning towards one of the Savage LRPV models, or else the same with a Shilen, or similar, premium after market barrel fitment.
 
Boils down to the bullet weight you want to use. I'm building mine with an 8 twist because I may shoot out to 800 with it but I have a buddy in Colorado that loves his 12 1/2 with 87 grains on prairie dogs.
 
If you plan on confining yourself to 85 grain and under, 12 twist is fine. If you think you might want shoot 105-107 grain bullets, you need the eight inch twist. Happily, the fast twist isn't half bad with lighter bullets either. One customer reported his best groups with 85 grain sierras with his eight twist BR. A decicated short range BR rifle should use a slow twist. Otherwise, I would go with a fast twist. Regards, Bill
 
Thanks for the input.
I guess my specific question would be , is there any issue with accuracy with the faster twist and heavier bullet over the other combo (slow and light) at the ranges I will be shooting most of the time?
 
Well I believe the benchrest folks use the slower twist and 70 gr. bullets and their accuracy requirements are second to none, and this would certainly carry to 3-400 yds. The fast twist would be strictly a very long range/heavy for caliber bullet thing, which of course would be better beyond 500yds.
 
Another issue you might want to consider in conjunction with twist rate is the amount of free bore -- if getting close to the lands is important to you. With the 8:1 twist you need lots of free bore for the long bullets to set them towards the lands and to keep them from getting to far into the "boiler room". On the other hand, you might want to check the free bore for the 12:1 twist because with short bullets, you may not be able to seat to the lands?
 
Gentlemen,
As always, your expert input is much appreciated.
I will likely go with one of the factory units with the 1:12 twist and shoot it out....
I can then decide if I want to replace it with a different barrel....
 
Hey guys! Is there no one else using a 1:10 twist in 6br? Mine shoots the 75gr V-maxes great as well as the 90gr VLD type bullets out to 600 yds. Makes for a great Varmint/Target rifle.
 
I ordered a 1-8" heavy, 36" barrel from Ted Gaillard and will chamber in 6mmBR. Checked inventory we have over 10,000 rounds of Lapua 105 grainers! Prefer handloads, but that's a pile of ammo that has been tested to about .25 MOA.

We'll talk.

Peter
 
Sav99takedown6mmBRcropped-1.jpg

I put a 14" twist Shilen benchrest take off 6mmPPC barrel on a 1917 Sav 99 and chambered it for 6mmBR. 21.5" of barrel was all that was left.

All I could fit was 33.5 gr W748 behind 75 gr Vmax.
It chronographs at 3050 - 3100 fps

At 50 yards it averaged 0.4 moa [averaged 0.2"]
At 100 yards it averaged 1.8 moa [averaged 1.8"] with some holes that were not round.

What does it all mean?
I achieved key holing with my slow twist 6mmBR.
 
Clark said:
Sav99takedown6mmBRcropped-1.jpg

I put a 14" twist Shilen benchrest take off 6mmPPC barrel on a 1917 Sav 99 and chambered it for 6mmBR. 21.5" of barrel was all that was left.

All I could fit was 33.5 gr W748 behind 75 gr Vmax.
It chronographs at 3050 - 3100 fps

At 50 yards it averaged 0.4 moa [averaged 0.2"]
At 100 yards it averaged 1.8 moa [averaged 1.8"] with some holes that were not round.

What does it all mean?
I achieved key holing with my slow twist 6mmBR.
Click to expand...

Use lighter bullets.

Jerry
 
I am curious to know how that Savage is supported at the fore end.
My Son's Mod. 70 6br has a 1:14 twist and the longest bullet it likes
is 70 gr Sierra ballistic tip.
 
peterdobson said:
I ordered a 1-8" heavy, 36" barrel from Ted Gaillard and will chamber in 6mmBR. Checked inventory we have over 10,000 rounds of Lapua 105 grainers! Prefer handloads, but that's a pile of ammo that has been tested to about .25 MOA.

We'll talk.

Peter
Click to expand...

There was a very interesting study done by the folks at 6mmBR.com and they actually found the velocity of a 6BR degrades in barrels over 31"
 
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