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Thread: Uniform rate of twist gives bigger "tuning window"?

  1. #1

    Uniform rate of twist gives bigger "tuning window"?

    I have no equipments to measure exact barrels twist rate uniformity.And I think it is difficult to many of us.

    We know from serious tests that "killer" barrel needs extremely uniform rate of twist.

    Is this one or main reason that some barrels are giving bigger "loading window" or bigger "tuning window" and are very "easy" to user???

    On this forum here is lot of knowledge and Mr Tolvstad & others has handled thousands? of barrels and this is why I ask this here.

    And because what we cant measure gives easily "mystery ideas" to head.

    BR, Timo

  2. #2

    Friend gun fool Timo

    Friend gun fool Timo


    Friend gun fool Timo:


    I believe I can evaluate a RFBR blank with my slugging, measuring and "feel" process and determine pretty much whether the barrel will be a killer, or not, with the exception of the uniformity of twist rate.


    I have a small handful of RFBR barrels in my shop that measure, slug and feel killer, and are chambered perfectly, that will not shoot.....so they never left the shop....


    I'm 99% sure that this small handful of RFBR barrels have a non-uniform rate of twist.



    Friend Timo, here's something to ponder:


    First of all, I suspect that very few button rifled RFBR barrels have a perfectly uniform rate of twist.


    Therefore...............


    What if the barrel makers could accurately measure the rate of twist of their barrels.


    What criteria would they use to determine how much deviation in the twist rate, and where its located, would they allow and still ship the blank to the customer?



    Your friend, Bill gun fool Calfee


    _________________________


    PS:


    Friend Timo:


    You ever hear the saying, "Let a sleeping dog lie"?


    I've got a feeling the barrel makers would be just as well off not knowing the twist rate of their barrels.....


    Cause if they did I doubt very few of their barrels would ever be shipped.....



    One other point:


    I do know of one button rifled barrel maker who has a machine to check twist rate....


    In RFBR today we rarely see barrels by this maker......although years ago this barrel maker was on top of the RFBR world.



  3. #3
    I dont know if someone button rifled barrel maker has find solution to "only" weakness of button rifled RFBR barrels. Non-uniform rate of twist.

    And IF someone find solution they keep it their "business secret".

    Not only solution but what helps is perfect "annealing" to barrel steel.And this is not easy part to make from barrel to barrel and thats main thing why uniform of twist rate is changing.And ofcourse if barrel steel is not homogenous everywhere we get problems when barrels temperature is changing.
    I have seen enough barrels on my life which shoots line when barrels temperature rise.

    BR, Timo

  4. #4

    Friend gun fool Timo

    Quote Originally Posted by Timo View Post
    I dont know if someone button rifled barrel maker has find solution to "only" weakness of button rifled RFBR barrels. Non-uniform rate of twist.

    And IF someone find solution they keep it their "business secret".

    Not only solution but what helps is perfect "annealing" to barrel steel.And this is not easy part to make from barrel to barrel and thats main thing why uniform of twist rate is changing.And ofcourse if barrel steel is not homogenous everywhere we get problems when barrels temperature is changing.
    I have seen enough barrels on my life which shoots line when barrels temperature rise.

    BR, Timo


    _________________________________


    Friend gun fool Timo:


    Excellent point.


    I was talking with Dan Muller one time and he said there's good melts of steel and bad ones.....


    This corrugated 8 he just made for Foster must have come from a good melt....


    Cause when Paul Tolvstad lapped it, he said it didn't fight him......I know exactly what he was referring to.


    ____________________



    Friend Timo, building RFBR guns like Black Death, for example, is a tremendous challenge...


    Even if we get a barrel with everything "perfect" about it, including the uniformity of twist rate, the thing still has to be chambered and fit properly to a "perfect" action, one that is custom "square" with the absolute most uniform ignition in the world or rimfire accuracy.......which means a Turbo Class, MD-PAS ignition action.


    Black Death meets all of those critical requirements.


    That's why Death, with Big Dog driving, produced the greatest, pure accuracy big national event performance in the history of RFBR.



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    But.................


    Timo, you're right, guns like Death must start with a button rifle barrel with a very uniform rate of twist.



    Your gun fool friend, BC


    ___________________________________


    PS:


    Timo......here's an interesting dichotomy in the world of rimfire barrels.


    Cut rifled barrels supposedly have better uniformity of twist rate than button barrels.


    And I can see why.


    But....................


    Cut rifled barrels are simply not competitive at big national RFBR events....


    Isn't that most unfortunate.....

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