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barrel twist VS grain weight.

Discussion in 'Gunsmithing' started by SLICE, Aug 28, 2017.

  1. SLICE

    SLICE WICKED PISSA

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    so as all of you know i was having one hell of time with my AR ( that was all my fault ).
    while at the range many of the expert shooters asked me what twist i have and what grain bullet i was using.
    i have 1.8 twist and shoot 55 grain FMJ 99% of the time. now i fully understand that all ammo is not the same.
    one of the more seasoned members said i should be using a barrel with a 1.9 twist for 55 grain FMJ.
    Discus.
    P.S. as Y'all know after many wasted rounds i finally have it dialed in, i'm praying it shoots dead nuts thursday because when i finally did get it dialed in 300 rounds went down the pipe.
     
  2. rharp

    rharp Dangling Member

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    Anywhere from 1:7 to 1-9 is fine for 55 gr. They say 1:9 is better for lighter projectiles while 1:7 is best for your heaver 69-77 gr. projectiles. Mine is a 1:7 and it shoots 55 gr. with an alarming accuracy. I haven't reloaded anything heavier to see what it will do. IMO, twist rate is not an issue with 223 if you have one of the common 1:7, 1:8, 1:9 twists.
     
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  3. WoodBurner

    WoodBurner Administrator
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  4. kypix

    kypix Class Clown
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    I have 1:8 and I shoot whatever is on sale.
     
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  5. WoodBurner

    WoodBurner Administrator
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    I have read that certain weight bullets do better with certain twist rates but I have zero experience.
     
  6. CarlWinslo

    CarlWinslo THIS SPACE FOR RENT
    KSG Club Poor Impulse Control

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    Every barrel has its sweet combo. Thats the fun of hand loading.
     
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    #6 CarlWinslo, Aug 28, 2017
    Last edited: Aug 28, 2017
  7. diesellover

    diesellover Well-Known Member

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    download (3).jpg Here's on diagram you really need to look at to get an idea. 1-7 has more trouble stabilizing 55 gr than 1-8 or 1-9 after 100 yards for example.
     
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  8. diesellover

    diesellover Well-Known Member

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  9. SLICE

    SLICE WICKED PISSA

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    thanks guys great info
     
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  10. r3dbull4dd1kt

    r3dbull4dd1kt Well-Known Member

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    Twist Rate and Projectile Weight is only part of the equation...barrel length and gas system setup are also factors...

    Both my 16" carbine and my 20" rifle have 1:8 twist rates...and both run different loads for optimum accuracy...

    For the Rifle, a Hornady BLACK 62 grain FMJ load is perfect; The match chamber is part of that as well but the primary factor is the OAL engaging the rifling with less freebore and the heavier projectile having 6 extra inches of barrel to stabilize

    In my Carbine, 62 BTHP have proven to be a better fit for distance...

    These are for 100yards or better; from 25yards out to 100, I prefer the 50 grain Barnes Varmint Grenade--mainly because of its devastating terminal effects and at the shorter ranges, any round is going where its aimed :)


    I suggest hunting down a box of the Hornady BLACK in 62gr FMJ and 75gr BTHP as well as any load that uses a 77gr Sierra Matchking--if you can get the specs, your loading source should be able to closely replicate them for you
     
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  11. bigmoguls

    bigmoguls Well-Known Member

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    My 7.5", 1:7 twist will hit what it needs to hit!
     
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  12. rharp

    rharp Dangling Member

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    It's cool. I always tell my wife that 4" is really 6", too.
     
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  13. r3dbull4dd1kt

    r3dbull4dd1kt Well-Known Member

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    Thats a keeper there!
     
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  14. Jimbo1

    Jimbo1 Well-Known Member

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    1/8 is my preferred twist. That being said I haven't seen a faster or slower rate just fall on its face at short range distances. Use good stuff to sight in then beat on it with fodder. Right around the 62g with a decent manufacturer will get you there . If it's way off bore sighting first will help or just use fodder to bring you into the ten and go from there.

    Range gurus know everything :confused:.



    Glad you have it worked out.
     
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  15. Nailbender

    Nailbender Shortened member

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    If my wife knew the difference, she'd be in trouble.
     
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  16. SDProf

    SDProf Vegetarian by proxy
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    Is the place to tell the story of the guy who was with a gal, and she said she could only be satisfied if he gave her at least nine inches and made it hurt?


    So he did her twice and whacked her upside the head with a brick.

    Back to topic - here, try this: http://www.bergerbullets.com/twist-rate-calculator/
    Trust me, you don't want to see the underlying math: https://en.wikipedia.org/wiki/Miller_twist_rule
     
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  17. rharp

    rharp Dangling Member

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    My high school shop teacher told me that joke during my sophomore year. Except he did her 3 times and punched her in the nose. Lol.
     
  18. SDProf

    SDProf Vegetarian by proxy
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    Well, a shop teacher ought t be able to accurately measure things. Better than a fisherman.
     
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