7.83 Twist/Bullet Weights...103+

[George M Rahn]

I'm interested in hearing from you all about bullet weight/performance with the 1-7.83 twist in bullets larger than 103gr. I've read all I can find including the thread on here a few years ago that I commented in, I've also used several twist calculators, some are more aggressive than others varying from inputting 105-109gr etc etc and being stable to others showing marginal. I'm fairly new to all this and would like to have the latitude to shoot 105-109gr bullets in this twist barrel or know the limitations of the 7.83. Speaking with barrel manufacturers is fine but there's nothing like real world thoughts/comments.
Thank You

 

[mac86951]

I'm interested in hearing from you all about bullet weight/performance with the 1-7.83 twist in bullets larger than 103gr. I've read all I can find including the thread on here a few years ago that I commented in, I've also used several twist calculators, some are more aggressive than others varying from inputting 105-109gr etc etc and being stable to others showing marginal. I'm fairly new to all this and would like to have the latitude to shoot 105-109gr bullets in this twist barrel or know the limitations of the 7.83. Speaking with barrel manufacturers is fine but there's nothing like real world thoughts/comments.
Thank You

I'm sure others will have a few more questions for you, so I'll help them out and ask now.

What velocity ranges or cartridge? A 6-284 will be more stable than a 6ppc.

What distance are you wanting to shoot? Better yet, what are your goals/plans?

What altitude / temperature as well as it matters.

In my experience the difference between stable and marginal has only indicated a potential to "like" or not like specific bullets; however, no calculator can tell you that. In fact, even stable twist calculations are still subject to that specific barrel performance and tuning. I think the real purpose of twist rate calculators is to let us know if something is borderline and maybe not waste our time, or to help explain the grey puffs and no target strikes of light weight bullets.

Technically a marginally stable bullet can still be accurate at distance; the reduction of gyroscopic stability could be considered a dividing scalar applied to BC (reduction of overall BC).

-Mac

 

[George M Rahn]

Thank you Mac I should have been much more specific. I'm a field shooter exclusively tactical or somewhere thereabouts. I am currently working with the 6GT, M.V. 2850-2930. I shoot out to 1200yds, my goals since I'm very new are to learn how to make my rifles shoot as accurately as I can learn to, I have shot nothing but Berger 105 Hybrids since starting but I am looking to broaden to the new 109 ELDM's but no larger than 109's.
I'm here in southeastern Ga so primarily sea level, temps mid 30's - mid 90's F. Thank you all!
-George

 

[mac86951]

Thank you Mac I should have been much more specific. I'm a field shooter exclusively tactical or somewhere thereabouts. I am currently working with the 6GT, M.V. 2850-2930. I shoot out to 1200yds, my goals since I'm very new are to learn how to make my rifles shoot as accurately as I can learn to, I have shot nothing but Berger 105 Hybrids since starting but I am looking to broaden to the new 109 ELDM's but no larger than 109's.
I'm here in southeastern Ga so primarily sea level, temps mid 30's - mid 90's F. Thank you all!
-George

Thank you for the added info, i think that will certainly help with recommendations; for which mine are:. 7.83:1 twist is kinda really specific, i would think that to be a pricey custom order over a more common 7:1 or 7.5:1. For your intended purpose; i would think a 7:1 would be just fine, and you'd not see a significant accuracy change in even some BR settings. The additional twist puts you well into the stability range; and doesn't over twist the lighter 6mms. If you're shooting only heavies, for sure; get a 1:6.5 and be done, shoot the 115s if you want; and it'll still handle all the 100+s with no problem.

I'm curious to see what others chime in with.
-Mac