Barrel flute timing?

Discussion in 'Gunsmithing' started by Hired Gun, Oct 1, 2013.

  1. Hired Gun

    Hired Gun Well-Known Member

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    I like my flutes situated so that at the stock line the barrel is solid as it is on all factory built rifles. On customs I regularly see guys timing the flutes so there is a gap at the stock. This leaves lots of room for debris to get under the barrel. This way is much easier to do as the timing isn't as critical and the stock fit doesn't have to be as precise. With it being done so much I'm starting to think people prefer the gaps.

    Any insight?
     
  2. J E Custom

    J E Custom Well-Known Member

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    In my opinion, you are doing it the right way.

    It looks better and makes the barrel to stock fit look much better.

    Its like on an expensive car, the seams on all parts are the same spacing and gives the feeling of quality and precision.

    There is always two ways to do something, The Right Way and the other way.

    J E CUSTOM
     

  3. MontanaRifleman

    MontanaRifleman Well-Known Member

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    JE, most barrels will have a crown of about a couple of thou or so. I have heard it's best to time the crown so it is in the vertical plane. Your thoughts?
     
  4. IdahoCTD

    IdahoCTD Well-Known Member

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    It's from the drill wandering during the drilling process. I orientate it either straight up or straight down.

    With some of the high flute count barrels it's not always easy to line up the high spots with the stock. I just did a Obermeyer fluted barrel and the flats are about 1/8" wide.
     
  5. J E Custom

    J E Custom Well-Known Member

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    Not sure what you are trying to do. Maybe I don't understand the question.

    After the barrel is checked for run out it is set up true to the bore on both ends and all work is done off this center line including the crown. There should be no difference in the vertical plane based on the orientation of the barrel/flutes if the barrel has little or no run out. I like to single point all crowns so they are true to the bore.

    If the crown is not square with the bore it should be re cut.

    On a fluted barrel it really doesn't matter what the orientation is for accuracy, it is just a matter of looks. If it is not timed one way or the other it really looks like poor workmanship.

    J E CUSTOM
     
  6. IdahoCTD

    IdahoCTD Well-Known Member

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    All bores are curved. They are turned on centers but some are like a jump rope between the two ends and some are out very little. He is talking about timing the curve of the bore into the vertical plane weather it is pointed up or down. If you have a long stem indicator you can dial a barrel in with the indicator in as far as it will go and then pull it out a inch or so and dial it in there as well. Basically your going in and out until that 1" section runs as true as you can make it. Then you run a indicator on the opposite end of the barrel to find the run out or "high spot". In theory this makes the point where the bullet enters the rifling as straight as possible to the bore.
     
  7. MontanaRifleman

    MontanaRifleman Well-Known Member

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    Yup, that is what I'm talking about
     
  8. J E Custom

    J E Custom Well-Known Member

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    If you look at the barrel makers acceptance criteria he will have an end to end tolerance.

    Most premium barrels that I use are guaranteed to be uniform dimensionally to within .0001
    and .0002 for Chrome Molly barrels. contours can be off on the outside by .000 to .005 (Industry
    standard acceptance)from end to end. Any more than this should be rejected and sent back to the barrel maker.

    I have had premium barrels go as high as .014 end to end and sent them back with no problems.

    Some factory barrels have had to be re-contoured to true them up. most are bore straightened
    after all work is done leaving the outside with run out because it was contoured while the bore
    was still as drilled and rifled.

    My preferred barrel makers barrels are normally .0000 to .0015 max.

    I have heard of this Barrel orientation thing because of barrels not being straight, but have never
    kept one that needed any special orientation due to being crooked/bent.

    So , If the barrel is straight and true to the bore , there is no special requirement for orientation.

    Some barrel manufacturers tolerances are more generous and may go up as high as .005 to .007
    and I just prefer not to use them.

    In My opinion : If you have to do something special to a barrel because of it's straightness it needs
    to be rejected and sent back.

    J E CUSTOM
     
  9. shortgrass

    shortgrass Well-Known Member

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    +1 to JEs post. If you have to do special 'orienting' to a barrel you need to send it back. You are living too much in the world of theory!
     
  10. Edd

    Edd Well-Known Member

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    I see this discussed frequently. There are two ways, that I know of, to dial in a barrel through the headstock. One of these methods will likely leave the need to clock the muzzle. That method seems to be the one most commonly used.

    Maybe You and JE could describe how you dial in a barrel blank before chambering.
     
  11. IdahoCTD

    IdahoCTD Well-Known Member

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    Typically barrels all fall within the specifications you gave JE even though the bore curves. Even if you cut them down the bore still is within the .005" tolerance you gave. I have seen a few way off yet they still shoot. This video explains things better than I will typing. Try it next time you dial a barrel in, if you have a long stem indicator, and see how far off the back end is.


    [ame=http://www.youtube.com/watch?v=rz3p95d3oL0]Straight Bartlein - YouTube[/ame]
     
  12. MontanaRifleman

    MontanaRifleman Well-Known Member

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    Interesting, the smith who recently did my 300 RUM, with Broughton barrel, said that he checks for the barrel's runout and times it so that it is either pointing up or down and not side to side. He is a very experienced and reputable smith. I guess there are 2 schools of thought on that. I thought he was talking in the thou range, maybe he was talking in the tenth of thou range?
     
  13. IdahoCTD

    IdahoCTD Well-Known Member

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    Here is another good video to help explain.

    [ame=http://www.youtube.com/watch?v=CdoyqhiSfvE]Dialing a barrel in on both sides of the bore. - YouTube[/ame]
     
  14. Hired Gun

    Hired Gun Well-Known Member

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    Just like these two video's, I dial in the bore of the end I am working on. If its the chamber end I dial the throat and then 2" farther in. Once dialed in the other end is frequently running out .005" to .040" and as much as .080". Very rarely do we see one running less than .010". I run an indicator on it to find where the barrel points up. I never point them down. If we overclock we take it around another turn to get it to point up. I then split the difference to orientate the flutes properly. This may have the curve pointing just slightly left or right but not by much. If I were to ignore the flutes it would make for a very bad appearance and will not ever orientate the flutes with a flute at the stock line. It looks terrible. You can have good looks and shoot.