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Twist rate for .308

FrancF
Do you think a 168 gr. serria HPBT will Stabilize with a 1-14 twist rate out of a 27" barrel? I have a feeling that is going to be marginal.


Thanks!

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  • JustC
    NO LESS than 1:12 if it were mine and 1:11.5 or so if I had my choice. Mike Rock M24 SWS system sniper barrels are 1:11.27 or something close. The 1:14 twist for 300yds competition. Go heavy twist,..heavy bullets!!!

    I ASSume you mean the 308win?

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • nononsense
    From Shilen's list:

    .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.
    *Stainless steel only
    ______________________________________________________________________

    Dan Lilja recommends 11, 12, 13 twist for 150 - 168 grain bullets
    ______________________________________________________________________

    I'm shooting the 168's in a 15 twist Krieger chambered for the 300 RUM and the accuracy is superb out to 600 yards.

    Best.
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  • FrancF
    Yep thats it, I was checking out the twist rate on my M1A and its a 1-12 but, 1-14? I did not think anything over 165gr would stabilize. So Ya know what I am looking at.

    I am going to try and see if they will put the 1-10 twist Brl. on it

    http://www.remingtonle.com/rifle/40xbtac.htm




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  • FrancF
    So based on the Greenhill Formula (I am learning here [:D]) The length of the bullet can put you on the boarder as well- Ie Work/No work
    .308 CAL 155gr Very Low Drag Recommended twist rate is 1/14
    .308 CAL 168gr Very Low Drag Recommended twist rate is 1/13
    .308 CAL 175gr Very Low Drag Recommended twist rate is 1/13
    .308 CAL 185gr Very Low Drag Recommended twist rate is 1/12
    .308 CAL 190gr Very Low Drag Recommended twist rate is 1/12
    .308 CAL 210gr Very Low Drag Recommended twist rate is 1/11


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  • Tailgunner1954
    FrancF
    Greenhill works well but it has it's limitations. You might do a little reading on www.lostriverbalistics.com (I think that's Lost Rivers website address) as MV has a effect on the stabilization formulia also (part of the Greenhill constant). A 308Win and a 30-378 require a different twist rate to get equil stabilization of the same bullet, due to the diferance in MV.
    FWIW I have trouble getting 165 NBT's spinning fast enough out of my 1-12 twist 30-06, but the 150gr NBT's do great when I keep the MV up around 3000fps
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • leeblackman
    I'd say just give it a try. It might not stabalize, but it won't blow up on ya or anything like that. Give it a shot, and see how it groups. If it doesn't group well then try something else. I'd probably look into maybe 150 or 155gr Sierra Matchking BTHP.

    What type of rifle are you shooting out of, a 1in14 sound like maybe a hunting rifle or something like that.

    I know my M1A will handle 175gr Hornady A-Max bullets fairly well, but hates 155gr BTHP's. I'd say 168's are about the best grouping in BTHP's but 175 in A-MAX. It had a 22" 1 in 12 twist 4 groove chrome lined. I used load data from the original 178gr national match load I found, but substituted with the 175gr bullet and used IMR4895 powder instead of WC846. It turned out a good thing. But it doesn't shoot as good in my Remington 700 heavy barreled 1 in 10 twist 6 grove as in my 1 in 12 M1A rifle. I found that my Rem700 like the 168gr Sierra Matchking better than the 175gr A-Max.

    In otherwords I spent that whole long paragraph to say that it depends on the individual rifle. Every rifle likes something a little different than the next no matter the twist rate.
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  • leeblackman
    You know tailgunner, that is true also i think. I know when I'm working a load for a rifle I like to work both up and down a grian or so and compare groups. Its amazing how much difference velocity can make on accuracy. You have to find the optimal velocity the bullet likes in your gun.
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