question on barrel twist

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by mrbb, Jan 21, 2010.

  1. mrbb

    mrbb Well-Known Member

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    Ok I been looking for advice,suggestions on a new build .
    I am going to build a 7mm08, and looking to have a finished barrel at 21 inches

    I would like to shoot 140 grain Ab heads, or there likes
    but am looking for advice on barrel/rifling twist
    I have been getting mixed advice on this, some say 1 in 9" and others say
    1 in 10"

    So what all do you guys recommend? think I would better off with??

    Thanks again
     
  2. Tikkamike

    Tikkamike Well-Known Member

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    for a 140 .284 bullet your gonna want a 1 in 11" barrel at a minimum. I like to go a little faster than that so 1 in 10" will be just fine, but 1 in 9" will enable you to shoot a heavier bullet later if you want to.
    Mikegun)
     

  3. Kiwi Nate

    Kiwi Nate Well-Known Member

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    With regard to a Hart barreled 7x57- I found that the 1:10 twist produced one hole groups with 140 grain bullets at 1" groups at 100 yards with 162 grain bullets. The groups simply opened up gradually as bullet weights were increased to 154 and then 162 grains. I agree with Mike, the 1:9 twist is good if you one day decide you want to play with heavy projectiles. I like the 140 grain AB for general use, its a good projectile but you might find yourself in a situation where you want to tweak your loads for a certain application in the future. As an example, the 7mm08 shines with the 162 grain Amax, very explosive and very fast killing, good on lean animals.

    Some of the heavy projectiles may seem slow on paper, but turn out to be shear dynamite out to 300 yards plus on game regardless of the low muzzle velocity. Its nice to have that option if you want to play later on.

    I also prefer a fat barrel contour on a short barreled rifle. I have a .308 Tactical, 20" jobby, always thought it was very light till I weighed it and found it was the same weight as my long magnums. Point is, I was completely fooled by weight distribution as opposed to actual weight. Even with the heavy barrel, I/friends complain about losing the sight picture during recoil. That said, I load the little bugger balls to the walls. I think the fat barrel helps this a lot too, seems to shoot sub .5 with everything up till it gets fouled up or too hot to touch (culling in NZ).

    I did some accurising work on a Sako Lightweight 21" barreled 7mm08 a while back, it was a real dog, I had to wait 30-40 seconds between shots and it couldn't handle a good fast load. Only gave sub MOA if I kept it dead cold and used just the right load- too finnicky for my tastes.
     
  4. 41mag

    41mag Well-Known Member

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    As others have mentioned the 1-9 would easily work for the 140's and let you use a heavier bullet for other conditions or purposes.

    Personally I would rather already have the added benefit, rather than wished I had it.
     
  5. J E Custom

    J E Custom Well-Known Member

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    Definitely go with the 1 in 9 twist !!!!

    It will handel all bullet weights from the 120s to the 180s.

    Barrel length is good (21'') and if you are hunting deer with it try the 120 grain
    ballistic tip, if hunting ELK use the 140 or 160 accubonds.

    The 7/08 is not the fastest 7mm (3100 with 120s and 2900+ with the 140s and needs
    a faster twist rate.

    J E CUSTOM
     
  6. theodore

    theodore Well-Known Member

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    +1 on 9" twist
     
  7. mrbb

    mrbb Well-Known Member

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    Thanks guys,
    just to clarify, I only plan to shoot 140's( unless for unknown reason they wouldn't group out of this new barrel I have planned)

    I have other guns, calibers for other stuff.
    I currently have a 7mm08, in a different gun( just not sure on what twist it has, done very long ago, and my memory sucks any more!)
    it is a #5 bbl on it at 24 inches, and shoot 140's like a champ!

    I just wanted to build another one, just a tad lighter, going with a #4 bbl fluted, at 20 inches!( and hopefully can shoot same load with same or very close results!)
    and was just looking for feed back of what you think the twist should be, since a few barrel companys, gave me different suggestions!
    some said 1-11', some said, 1-9, and most said, 1-10.

    so I was just wondering what anyone on here has used, and how it worked out!

    But it looks like most here think 1-9 is the way to go, or 1-10, since I don't plan to use heavier than 140's,

    do you feel i should still go to the 1-9, or use a 1-10??

    thanks again
     
  8. 41mag

    41mag Well-Known Member

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    If you were absolutely looking to squeeze every last fps out of the cartridge I would suggest going with a slower twist.

    With the 1-9 your not going to notice anything different about the way it handles your loads, with the standard 140's. However if you decided to shoot some Berger 140's that would give the faster twist a better handle on the longer bullet.

    Also who knows what the future might hold.

    I got a 7mm Rem Mag and was going to only shoot the 130 - 150 rg bullets and still haven't worked up a load for them yet. I got a deal on some 162gr bullets and they have been shot in it since I have had it. I also have a STW and other than playing with a few of the heavy bullets, I am shooting factory Federal 150gr Nosler Solid base loads in it. Go figure.

    Good luck with which ever you go with, one last thing, depending on who you end up going with, some might already have one with a 9 twist sitting there ready to go where they might have to make the slower one. Just something to consider and ask about when you order. With the time it sometimes takes to get one made and delivered, I know that would definitely make a deal for me.
     
  9. theodore

    theodore Well-Known Member

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    I shoot 105 VLD- they recommend 8" twist but it does very well out of my 243 win steven rifle that is 9 1/4" twist. But this loaded maxed out with the most velocity/lowest pressure kind of powder I could find(3050fps). Always thought that the higher velocity is what stabilized the bullet.
     
  10. J E Custom

    J E Custom Well-Known Member

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    The reason I recomended 1 in 9 is because it has always worked no matter what bullet
    I shot in the 7/08s I have seen or built.

    I shoot 120grain bullets in my 7/08 and the best 5 shot group to date has been .053 @ 100
    yards. It will also shoot the 140gr and the 160 gr Accubonds under 1/10th of an inch (.100).

    The slower or faster twist may work well for specific bullets but the 1 in 9 is the best all
    round twist rate in my opinion.

    J E CUSTOM