6 BR Twist Rate

[BBouncer5150]

I haven't posted on this board much, but I've been lurking here for several years as I feel like this forum has the best information available for reloading for accuracy. I don't hunt or compete anymore (I used to shoot some 3 gun, never BR), but shooting is my main hobby and I enjoy chasing the smallest groups I can from the bench at ranges between 100 and 300 yards. With that being said, I recently picked up everything I need to put together a Savage short action with a Shilen Select Match Stainless 6BR Norma, bull contour, 1-8 twist. I went with the 1-8 as I initially intended to shoot the heavier 105-108gr class bullets. However, I have a ton of match bullets in the 68-85gr range that I would also like to use in the 1-8 barrel. From what I've been reading, a 1-13 or 1-14 is better suited to shooting the 68gr bullets insofar as accuracy goes. My question is, what kind of difference can I reasonably expect to see using the 68gr bullets in the 1-8 vs if I had a 1-14? Are we talking a big difference or something like say in the thousandths? Just curious...thanks for the assistance.

Matt

 

[Allen Corneau]

As far as I understand it, as told to me by industry professionals, as long as you're not trying to achieve ridiculous velocities and using well made bullets, there's not really an issue of "over-stabilizing" a bullet with a faster twist-rate barrel than necessary.

Now if you're trying to eke out the smallest groups possible then an optimum twist rate for the bullets you're wanting to shoot would most likely be the road to success, but you never know.

Unfortunately I can't point you in the direction of any scientific studies on the effects of group size versus optimized barrel twist rate, but it's possible there may be something out there. Check with the Applied Ballistics folks/website.

Best of luck.

 

[slickshot223]

Not much help but I have a 6BR Remington with Shaw 1-10 tw stainless barrel that shoots 55, 70, & 80 gr bullets very well, like ragged hole groups at 100!! 55's work quite well on the ground hogs!!

 

[alintx]

I have a 7 twist that loves 68gr br bullets. I don't run hot (31 hrs of varget) as I shoot LOTS of pasture poodles and didn't wanna burn it out faster than necessary. I have br's in everything from 13.5 to seven, and can't tell much difference in accuracy, they just shoot

 

[divingin]

If you have Facebook, Bryan Litz (ballistician at Berger) has been posting small excerpts from his Science of Accuracy books, and has fairly recently had a couple of posts regarding faster than normal twist rates. His general conclusions point towards it being fairly unlikely to overspin a bullet (until you reach the disintegration rpm), and that it will improve the downrange BC of a given bullet/velocity to at least some degree.

https://www.facebook.com/BryanLitzBallistics if you want to get there. I don't see a method of referencing a single post

 

[SeabeeKen]

If you have Facebook, Bryan Litz (ballistician at Berger) has been posting small excerpts from his Science of Accuracy books, and has fairly recently had a couple of posts regarding faster than normal twist rates. His general conclusions point towards it being fairly unlikely to overspin a bullet (until you reach the disintegration rpm), and that it will improve the downrange BC of a given bullet/velocity to at least some degree.

https://www.facebook.com/BryanLitzBallistics if you want to get there. I don't see a method of referencing a single post

Perhaps but I have a 8 twist 6xc that just wont shoot light bullets but shoots .027 group with 108 gr EH. My 22xc shows the same tendency. Matching weight to twist seems to improve accuracy IME

 

[marchx]

I am trying the slowest twist rate acceptable by my bullet of choice. Now, I shoot 105 Barts and 1:8 twist.

 

[urbanrifleman]

Perhaps but I have a 8 twist 6xc that just wont shoot light bullets but shoots .027 group with 108 gr EH. My 22xc shows the same tendency. Matching weight to twist seems to improve accuracy IME

Spinning a bullet that is slightly off (manufacturing wise) even faster, probably makes any flaws more evident. So, in my opinion, the better the quality of the build of the bullet, the more it will tolerate over spinning and not ruin accuracy.

 

[SeabeeKen]

Spinning a bullet that is slightly off (manufacturing wise) even faster, probably makes any flaws more evident. So, in my opinion, the better the quality of the build of the bullet, the more it will tolerate over spinning and not ruin accuracy.

I agree. In my rifle however, it preferred heavies to even light Hammer bullets which are perfectly made bullets. I tested others also and this proved out on target after target.

 

[urbanrifleman]

I agree. In my rifle however, it preferred heavies to even light Hammer bullets which are perfectly made bullets. I tested others also and this proved out on target after target.

Sure.

Most likely the very smallest groups will be found near the ideal twist.