Understanding Barrel Twist-Bullet Weights - Page 2
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Old 07-01-2011, 04:02 AM   #11
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Just to add a point, larger calibers have slower twist rates. A .30-06 may have a 1 in 10 twist rate for a 180 gr bullet. Something like the 458 SOCOM may have a 1 in 14 or slower.

I know the OP is kind of geared towards .223 though.

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Old 07-01-2011, 04:12 PM   #12
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Camron,

You are correct the thread was totally referring to the 5.56 ARs. There are a lot of other factors to consider when talking about larger calibers and even heavier bullets. Even the length of certain caliber projectiles has a bearing on selection of the correct barrel twist. The old Swedish Mauser comes to mind. They look very different do to the length of the bullet that is exposed out of the case. It is one long projectile (Bullet) compared to most. All this plays an important roll to achieve the optimum stabilization in flight.
I am very familiar with the 458 SOCOM! Great Round! And a hard hitter!
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Old 07-01-2011, 05:22 PM   #13
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Very informative and helpful!

Thanks for taking the time to write that up. I appreciate it!

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Old 07-01-2011, 11:38 PM   #14
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This is a great thread. Thanks for sharing this wealth of information with us.

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Old 07-01-2011, 11:51 PM   #15
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Thanks for the info! Fantastic!

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Old 07-02-2011, 04:26 PM   #16
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Sniper03, excellent thread, well written and I'm glad JD made it a sticky. I do have a suggestion for a small change to this area:

Quote:
Twist to Bullet Weight: Suggested Range

1:12 Twist 42-55 grain range
1:9 Twist 55-72 grain range
1:8 Twist 55-79 grain range
1:7 Twist 62-77 grain range
the last barrel twist would make more sense if changed to:
1:7 Twist 62-80+ grain range
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Old 07-02-2011, 05:43 PM   #17
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Default Bullet lenght.......

So where does this come into play with twist rate when the weights are the same but bullet lenght is different. I've heard that it's not weight but lenght that controls the amount of twist you would need for that specific round. Curiosity killed the cat.....

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Old 07-02-2011, 06:49 PM   #18
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Longer length, faster twist.

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Old 07-02-2011, 07:02 PM   #19
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Good point, willshoum. Length actually is the more important factor and if this were an exact science we'd probably use that factor. And we'd have to bring in how an individual barrel actually works, not how its twist rate usually works.

But since we can generalize that longer bullets are also heavier and that it's easy to read the bullet weight right off the box where bullet length is something you have to dig harder for - weight is the factor most people discuss when twist rate comes up.

I don't know how long a 55gr or 69 gr bullet is and most people don't. So we tend to use this shortcut since it works well enough most of the time.

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Old 07-02-2011, 07:04 PM   #20
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Great info, thanks! Cleared a few things up

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