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Barrel Twists

0311
Just have a question about the rifling in the barrel. For example, I see 1 in 7 and 1 in 9 twists for some rifles, how does this work? The longer the twist, the longer the range or the other way around. Is this where the accuracy in a rifle comes into play. That is all and thanks.

Cpl Brandon L. Tanner/USMC
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Comments

7 comments

Date Votes
  • JustC
    The heavier/faster the twist,..the heavier the bullet it stabilizes. Fast twists are usually for longer range, heavy bullet barrels.

    a 1:7 twist will stabilize a heavier bullet better than a 1:9 twist. There is no distance difference per-se,..but the heavier bullets will shoot accurately farther due to retained energy and ability to overcome wind and gravity. It boils down to bullet weights and bearing surface lengths more-so than actual distance.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • Colt Super
    Is there anywhere to find a comarison test of different weight bullets from different twist barrels?

    For instance: 40, 50, 55 & 60 grain .223s from 1:7, 1:9 & 1:11 twist rates.

    I'd like to know this info so that when I finally build my custom rifle (I may be with the Lord before I can afford to - but I've heard there are some good gunsmiths there waiting for a new project), I'll be able to specify twist. I'm pretty sure the rifle will be a 7MM.

    God Bless America and...
    NEVER Forget WACO
    NEVER, EVER Forget 911
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  • Tailgunner1954
    Brandon
    FYI It's 1 complete revolution of the bullet in X inchs so a 1-7 is faster than a 1-10.
    Each "LENGTH"* of bullet needs to spin at (or slightly above) a certen RPM to stabilize. This "spin rate" is controled by both the twist rate and the muzzle velocity. A 22Hornet @ 2500fps and a 22-250AI @ 4000fps would need a completely diferent twist rate to stabilize the same bullet due to the difference in MV.

    Doug
    Recogmended twist/bullet weight* charts can be found on a lot of the barrel makers sites IE: Shillen, Lija, Kreeger, Douglas, Pac-nor etc.

    *While bullet weight is used on the charts, it's actually the LENGTH of the bullet that matters. A "VLD" style bullet needs a faster twist rate than a "flat base round nose" style of the same weight.
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • rhmc24
    Tailgunner nailed it. Stated simplest, the longer the bullet the faster the twist. Frigzampl small bore long fast bullet maybe 10 inch twist, round ball as in black powder maybe 60 inch twist.
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  • JustC
    Doug,..the Shilen website has a twist rate chart.

    My suggestion would be a 1:9 twist in the 7mm to stabilize the 160-175gr VLD type long range loads. For the 140-150gr pills,..I would go 1:9 1/2". FWIW

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • nononsense
    Here's the link to the Lilja twist rate chart:

    http://www.riflebarrels.com/products/caliber_twist_rates.htm

    There is also a good description in the FAQ section about how to pick a twist rate.

    Best.

    Here is the Shilen chart from SST's Rifle Room:

    Caliber Twist

    .172 9" For bullets heavier than 30 gr.
    10" For bullets up to 30 gr.

    .204/20 12" For all bullets.

    .222 RF 14"* Twist for pistol barrels
    16" Standard twist for rifle barrels
    17"* Special twist for rifle barrels

    .224 CF 8" For bullets heavier than 70 gr.
    9" For bullets up to 70 gr.
    12" For bullets up to 63 gr.
    14" For bullets up to 55 gr.
    15"* For bullets up to 55 gr. driven 4,100 fps or more
    16"* For bullets up to 55 gr. driven 4,300 fps or more

    6mm/.243 8" Special for VLD bullets over 100 gr.
    10" For bullets up to 120 gr. and VLD under 100 gr.
    12" For bullets up to 85 gr.
    13"* For bullets up to 75 gr.
    14"* For bullets up to 70 gr.
    15"* Special for bullets up to 70 gr.

    .257 9" For bullets heavier than 100 gr.
    10" For bullets up to 100 gr.
    12" For bullets up to 90 gr.
    13"* For bullets up to 80 gr.
    14"* For bullets up to 70 gr.

    6.5mm/.264 8" For bullets heavier than 130 gr.
    9" For bullets up to 130 gr.

    .270 10" For all bullets

    7mm/.284 9" For bullets heavier than 140 gr.
    11" For bullets up to 140 gr.

    .307 13"* Special size and twist

    .308 8" For bullets heavier than 220gr.
    10" For bullets up to 220 gr.
    12" For bullets up to 170 gr.
    14"* For bullets up to 168 gr.
    15"* For bullets up to 150 gr.

    7.65mm/.311 10" For all bullets

    8mm/.323 10" For all bullets

    .338 10" For all bullets

    9mm/.355 14" For low-velocity wadcutters
    16" For all other bullets

    .38/.357 14" For low-velocity wadcutters
    18" For all other bullets

    .358 14" For all bullets

    .375 12" For all bullets

    10mm/.400 16" For all bullets

    .411 14" For all bullets

    .416 14" For all bullets

    .44 20" For all bullets
    16" For low velocity wadcutters

    .451 16" For all bullets

    .458 14" For all bullets


    *Stainless steel only
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  • Colt Super
    Gosh, you guys are good! Thank you.

    God Bless America and...
    NEVER Forget WACO
    NEVER, EVER Forget 911
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