Contour and twist choice for .280ai barrel

Discussion in 'Rifle Country' started by wombat13, Nov 29, 2021.

  1. wombat13

    wombat13 Member

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    I hope to visit the gunsmith and order the barrel for my first rifle project this week. I am having a Ruger Hawkeye .25-06 rebarreled to .280ai. I plan to use a Hart barrel since they are an upstate NY company. I'm not sure what twist rate and contour to go with. I'll use the rifle mainly for hunting. As of now, I can only target shoot out to 200 yards. There is a 600 yard range a couple of hours away that maybe someday I'd go to.

    Here are the choices Hart offers:

    Twist rate options: 6 Groove in 8", 9", 10" or 12"; 5 Groove in 8"

    Contours: Douglas 2, 3, 4, 5, and 5.5 or Remington Varmint, Mag, ADL/BDL, Mountain Taper

    I have no idea about the pros/cons of 6 vs 5 grooves. I shoot mostly Nosler and Barnes bullets. Their load data indicates 9" twist, except Barnes recommends 8" for the 168 gr LRX. I don't know if I'll ever use that bullet, but what is the downside of going with 8" instead of 9"?

    Finally, those contours mean nothing to me. I'd like a sporter weight barrel. Not so heavy that it's a pain to carry and not so light that barrel heating makes it a chore to work on loads for the rifle.

    Finally, straight 6 groove fluting is available for $120. Other fluting profiles are available for $180. Flute it or not?

    What would you do?
     
  2. gotboostvr

    gotboostvr Member

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    I'd go 1:8 twist, ADL/BDL profile.


    Going too fast is only really an issue if you're shooting very light varmint bullets at ridiculous speeds. But even then, 1:8 isn't really fast of a twist. You should be able to run the full gamut of 120-175gr bullets in that barrel.

    The ADL/BDL profile should match the standard Remington sporter barrel profile. The mountain profile may be too light for you.
     
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  3. wombat13

    wombat13 Member

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    My reference for barrel contours are Ruger M77/Hawkeye and Savage (Axis). How does the Remington ADL/BDL compare?
     
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  4. gotboostvr

    gotboostvr Member

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    It's the "normal" barrel profile on bog standard Remington 700's. Not an ultralight pencil barrel, not a heavy varmint barrel.

    It should be fairly similar to other normal sporter profile barrels.
     
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  5. BreechFace

    BreechFace Member

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    If it were me I would try out the 5 groove, 1:8” or 1:9" twist, with a ADL based on their dimensions.
     
    Last edited: Nov 29, 2021
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  6. Txhillbilly

    Txhillbilly Member

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    I'd go with the 5.5 or Magnum contour - they are the same. It's just slightly bigger than a Sporter contour, but will allow you to shoot more shots before the barrel gets hot.
    1-8 twist, # of grooves really doesn't matter 5 or 6. Fluting is pretty much just cosmetic, I don't waste money on it.
     
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  7. wombat13

    wombat13 Member

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    Why the 5 groove rather than 6?
     
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  8. .455_Hunter

    .455_Hunter Member

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    When I was an early teenager and got my first milsurp- a Spanish 1916 Short Rifle in 7x57mm. I remember reading that the rate of twist for these guns was 1-8.5" or so, and optimized for the 170 - 175 gr RN loadings common at the time. The fact that commercial 140 gr loads would shoot less accurately was a direct statement, and not a theoretical discussion at the time.

    I guess things have changed (?)
     
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  9. BreechFace

    BreechFace Member

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    They seem to shoot a little faster with some gains in less engraving pressure on the bullet heading down the barrel, but its hard to eliminate the other variables when testing two of the same chambered rifles with different rifling.

    Mostly because I've had good luck with some 5R barrels before, so much of it's personal preference on that.

    I don't think you will notice much difference but if it were my choice that would be what I would order.
     
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  10. LoonWulf
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    LoonWulf Contributing Member

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    Id guess that was more related to the long throats those 160rn would probably require. Ive never handled one of those Mausers tho so thats just a guess.




    Id also go 1-8, with a magnum profile
     
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  11. .455_Hunter

    .455_Hunter Member

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    That could be, but the twist rate was specifically called out at the time.

    Does anybody know what the standard commercial twist rate is (was) for 7x57mm? Did it change over the years?

    Interesting discussion on 7mm Rem Mag custom barrel twist rate...

    https://discussions.texasbowhunter.com/forums/showthread.php?t=653461
     
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  12. Chuck R.

    Chuck R. Member

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    Check with Hart to see what profile they'll flute... Some barrel makers won't go lower than "X" profile for fluting.

    IF hunting involves getting to a stand/blind and sitting, I'd have no issue going with a 4 or 5 profile, 24" tube with 8 or 9 twist and having either fluted. Fluting will shave some weight, but not much, especially if they're shallow on a light contoured barrel. IF it was a general purpose rifle I'd lop 2" from the 24" length

    Still hunting/hiking I'd go with a #3, 20-22" but I've got other rifles dedicated to target shooting.

    I'm waiting on the return of a 20" Bartlein 2B (medium sporter) profiled barrel now that's been fluted. The 2B is a lot like other makers 3 or 4 contour and it's going on a Rem M7 that will be used for a mid-range stand/blind gun and still hunts.
     
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  13. wombat13

    wombat13 Member

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    For now, all of my hunting is in the northeastern woods. I'm not good at still hunting, so I tend to do a lot of homework in the off-season and pick my spots. I wouldn't want longer than 24" and shorter than 22" seems short for a cartridge that's putting about 60 gr of powder down the tube. Looking at the ratio of the case volume to bore area (what I call the expansion ratio) puts this between .30-06 and .300WM. Rifles in .30-06 are often offered with 22" barrels and .300wm often with 24" barrels it seems like that's in the right range for barrel length.
     
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  14. LoonWulf
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    LoonWulf Contributing Member

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    Most commercial 7mm/284 dia have run a 1-9 to 1-9.5 from what i remember.
    You dont really need a 1-8 till your into the 168+vlds and most of them still do ok in a 1-9.
     
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  15. troy fairweather

    troy fairweather Member

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    Cip spec on twist are 1-8.66. Most guns are 1-9 to 1-9.5. 1-9 1/4 was pretty popular as well. I would get between a heavy sporter and a magnum contour. I have a #2 Douglas on my 7x57AI and like it but it's a deer rifle, you just mention target shooting tho. You will need stock work most likely.
    Last quote I got from hart was over $700 Douglas was $500.
     
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  16. wombat13

    wombat13 Member

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    The smith told me to figure $400 for the barrel and $200 for his work.
     
  17. Varminterror

    Varminterror Member

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    1:8” 5 groove magnum Sporter contour (forget where it is between 4, 5, or 5A). Enough heft and forward balance to let me shoot the rifle as far as I could want with great stability and avoid barrel heat, enough weight to soak up a little recoil, but not so much I’d feel dumb carrying all day.
     
  18. Archie

    Archie Member

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    Twist: A lot of overspin is preferable to a little underspin. The virtue of the 7mm caliber has always been heavy bullets, so adjust for the heavier end.
    From what I remember of number of lands/grooves, quality is much better than quantity. Early U. S. .30 caliber rifles had some TWO groove barrels that shot as well as others.
    The outside diameter of a barrel is dependent on purpose: The greater the outside diameter, the faster it radiates heat and stays cool better. The greater the outside diameter, the more steel is involved and it gets heavier. Decide what YOU want.
     
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  19. DR505

    DR505 Member

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    As for the fluting, I just read the Shilen web site as I am considering a barrel swap. They highly discourage fluting of any barrel and they explain it very well.

    They also explain why cryo is also a waste of money.
     
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  20. wombat13

    wombat13 Member

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    I'm trying to decide what I want. The challenge is that I don't own that many rifles, so I don't have much to reference. Right now, I have two Ruger Hawkeyes with 24" barrels (I've also used my FIL's M77), a Savage with a 22" barrel, a Ruger 10/22, and a Garand. I've never had a custom barrel made, so I am completely unfamiliar with the various contours and the two groove choices. I understand the tradeoffs of weight/heat dissipation (barrel diameter) and weight/speed (barrel length) in a theoretical way but not in practice.
     
    Last edited: Nov 30, 2021
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  21. old heeler

    old heeler Member

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    If you like how existing rifle handles you may find contour that match close so you won't have to do lot stock work. You might want to talk to gunsmith about that.
     
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  22. gotboostvr

    gotboostvr Member

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    That's the best way to approach this.

    Do you like how it currently handles?

    If yes, match it.

    If no, do you want it heavier or lighter?
     
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