6.5 twist requirements

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by joe boyd, Jul 21, 2005.

  1. joe boyd

    joe boyd Active Member

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    What is the neccessary twist for a 6.5- 300 wsm ? Understandably, this will not be a target gun, but rather for big game hunting only.

    Kirby, or someone who knows, what is the required twist for a 6.5 Allen Mag ? Again, built for hunting.

    thank you
    Joe
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Joe,

    For the 6.5 WSMs I have built, I have only used 1-8 twist barrels, Lilja and Broughtons. Both shot every bullet from 100 to 155 gr extremely well.

    IF you will be shooting 120 to 140 class big game bullets the 1-9 twist will be plenty in a rifle. Just for instance, My 6.5-06 AI shoots the old 155 gr SMKs into tight little groups and it has a 1-9 twist barrel.

    Same goes for the 6.5mm Allen Mag. If you will be shooting 120-140 gr bullets I would recommend a 1-9 or 1-10. IF your planning on VLD or ULD bullets, first off, they have to survive the velocity potential and second I would recommend a 1-9 for the 140-142 class VLDs and a 1-8 for the heavier pills such as the 150, 160, 165 and 169.5 gr ULD RBBTs.

    These are still to be tested. I have the receiver, stock and barrel, just need about 10 free hours to put her together, don;t see that happening anytime soon but I hope it happens here in the next couple weeks.

    Basically for conventional big game bullets, the 1-9 is hard to beat for all hunting conditions with the 6.5mm rounds.

    Kirby Allen(50)
     

  3. Mikecr

    Mikecr Well-Known Member

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    What's your hunting altitude?
    For a 142ULD, 1:9 works in Montana . Near sea level, 1:8 is marginal.
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Mikecr,

    If you want to use the 142 gr ULDs I would use the 1-8 twist, especially in the 6.5 WSM class rounds.

    For the 6.5mm Allen Mag, I have to test this and see if the bullets will handle the strain of this twist at these velocities, I suspect a 1-9 would be a better choice but thats adding 500-600 fps to the WSM velocity potential, hell, a 1-10 may be all that is needed??? Have to test it yet.

    Kirby Allen(50)
     
  5. jb1000br

    jb1000br Well-Known Member

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    Kirby-- why would the 142WC need more twist that a 140amax or 142SMK?

    look the same length in my pic... or within 10thou anyway.

    [​IMG]

    the little squares are 1mm or about 0.040"

    JB
     
  6. joe boyd

    joe boyd Active Member

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    jb100br,
    Thank you, now I understand why a picture is worth a thousand words. Kirby, thank you too, I guess you realize you shot my idea down.
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    JB,

    They wouldn't.

    Lilja recommend a 1-8 for all the 140-155 gr VLD designs. Dan is alot like me, better to be conservative then to deal with pissed off customers.

    I have used the 1-9s with the 140-155 gr VLDs and have had great results but still would prefer a 1-8 just for the extremes.

    Also for big game hunting I would rather have a bit more spin. I do not BR shoot so the absolute ultimate in accuracy as far as matching bullets to twist rates concerns me very little. I want as much accuracy as I can get in a 100% reliable package. For that reason I recommend 1" faster twists then what is probably needed, still, you will not go wrong with this class of round.

    Now for the 6.5 AM, with the dramatically higher velocity, bullet integrity will be an issue so I would recommend dropping to a 1-9 or even 1-10 but like I said, I will need to test that to make a solid recommendation with that round.

    Kirby Allen(50)
     
  8. jb1000br

    jb1000br Well-Known Member

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    Kirby...understood /ubbthreads/images/graemlins/wink.gif

    The 1:9 is even working in a couple 6.5WSSM;s that i know of...even with the older Loooong Amax.

    would have had one in the pic, but i broke the damn tip off when setting up the pic /ubbthreads/images/graemlins/frown.gif

    JB
     
  9. Mikecr

    Mikecr Well-Known Member

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    JB
    I'd be surprised if the 142WC shot well from a 1:9 at Bodines. Regardless of Velocity. The bullet clearly has a longer bearing surface than the others, but weighing the same for length. So it's specific gravity must be lower. At an elevation of ~1200ft ASL, 1:9, this bullet looks -barely stable- to me. I'd be interested enough to send a box to you or Boyd. Maybe you could load up some for 1k testing. If they work in a 6.5/284 or WSSM there, I'll order a bunch more. Let me know
    I happened on a few 1:8.5 Border barrels for my still unfinished 6.5/WSSM. So I'm curious. I got the impression from Boyd that 1:9 was not ideal.
     
  10. jb1000br

    jb1000br Well-Known Member

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    Mike....here is this from Boyd...

    Mike.I have shot the 140 A-Max that call for a 1-7.5 twist out of my
    6.5 Heaton 9 twist at around 2900fps down to about 40 degrees at Mifflin
    with JB1000 there.Jasons words were (I thought you said it did'nt shoot
    at 100 yards)I think a 9 would be enough if you did'nt try to shoot
    them in the artic /ubbthreads/images/graemlins/laugh.gif ...I would be interested in trying the wc 142.I
    know he made me some 120's to try that shot well.But not any better than
    anything I have quick access too.The old 140A-Max shoots like a house a
    fire out of both my 6.5's.Saving them for critters though...Boyd
    -------------------------------

    Now me:
    BTW -- Richard sent me some 142's but they were too long for me to shoot -- will be way down in my powder column -- boyd's 6.5 may be better set up to handle these as they have the same bearing surface as the new 140amax /ubbthreads/images/graemlins/wink.gif (which i also cant shoot)

    JB
     
  11. Mikecr

    Mikecr Well-Known Member

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    I'll get up with Boyd &amp; send some for a test(When I get off nightshift). I do really believe the the 140AMax, with it's plastic tip, is completely different from a 142WC RBBT ULD, when it comes to stability.