GUN Twist rate question

Discussion in 'On Topic' started by Fire Sauce, Oct 2, 2008.

  1. Fire Sauce

    Fire Sauce New Member

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    So I just recently completed what has to be the longest AR build in history (thread coming soon), and had some questions about my barrel.

    With 1:9 twist, is that fast enough to stabilize something like TAP FPD? Or should I stick with XM193?
     
  2. LancerV

    LancerV Something Happened OT Supporter

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    Depends are we talking about personal defense load, or long range loads. I would think 75gr for personal defense says less 150yds would be fine out of a 1:9
     
  3. yar1182

    yar1182 New Member

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    Truth
     
  4. jabbadeznuts

    jabbadeznuts ΜΟΛΩΝ ΛΑΒΕ

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    Per Wikipedia, the twist rate needs to be something like this:
    [​IMG]

    where:
    • C = 150 (use 180 for muzzle velocities higher than 2,800 f/s)
    • D = bullet's diameter in inches
    • L = bullet's length in inches
    • SG = bullet's specific gravity (10.9 for lead-core bullets, which cancels out the second half of the equation)
    http://en.wikipedia.org/wiki/Rifling
     
  5. Paul Revere

    Paul Revere OT Supporter

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    damn :eek3:

    but yeah as yar said:

    55gr: 1:7 to 1:12
    62gr: 1:7 to maybe 1:9
    above 62gr: 1:7
     
  6. Milky

    Milky I'm in your Millenium Falcon, rumbling your Wookie

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    So is 1:7 the best overall twist rate to get in an AR?
     
  7. It just depends on what you want to do with it. If you're looking for a varmint gun where you'll be shooting something like Black Hills' 36gr ammo, then you definitely don't want a 1:7 twist. If you're looking for a gun for home defense or longer range target shooting then you'll want to fire the heavier bullets and will want a faster twist. You've just got to decide what the gun is for before you choose a twist rate.
     
  8. Paul Revere

    Paul Revere OT Supporter

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    i wouldn't get an AR in anything other than 1:7 :dunno:

    edit: ok, maybe 1:8 but it would be an SPR or something similar
     

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