Checking for stress free Bedding.

Discussion in 'Gunsmithing' started by BRIT, Aug 25, 2010.

  1. BRIT

    BRIT Well-Known Member

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    Hi Gents
    After a Rifle is Bedded how does one check to ensure it is stress free? I know a DTI is involved but not sure how and why this is used.

    I would greatly appreciate some help in running through the process.
    Also i bedded the first 1.5 inches of Barrel as part of the Bedding job. Was i correct to do this?

    The barrel has a 4 inch shank with straight taper down to 0.795 at 26 inches. Action is Borden Timberline.

    Thank you

    Brit.
     
  2. Hntbambi

    Hntbambi Well-Known Member

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    Sep 26, 2008
    I have always done it by checking for barrel movement as the front action screw is tightened or loosened. Once the front and rear action screws are properly torqued, place dial indicator on the barrel and read the movement of the barrel relative to the stock as the action screw is loosened. If there is stress, it will usually show up in barrel movement.

    As far as bedding under the chamber, its up to the gun. I have seen some that benefited by it,m and others that liked to be totally free floated. On a custom action I would expect it to be stiff enough that the bedding under the chamber is not needed unless the barrel is full bull and 30" long.
     

  3. royinidaho

    royinidaho Writers Guild

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    Brit,

    The quick and easy way is to tighten the action screws then hold the rifle vertically with the butt on the bench. Hand would be around the barrel and forearm. As the screws are alternately loosened and tightened you will feel any movement with your hand.

    It it seems worth measuring the movement get one of these gizmos and mount it on the barrel with the dial indicator somewhere near the sling swivel stud. Then alternately loosen and tighten screws. Movement should be very minimal. I go for less than 0.005 but it it shoots good in all kinds of weather I'm satisfied.

    It's usually good to bed a bit of the barrel. It changes the harmonics but even my custom gun as about 3" ahead of the lug bedded.

    [​IMG]
     
  4. J E Custom

    J E Custom Well-Known Member

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    To check if there is flexing when tightening the action screws place a magnetic dial
    indicator base like in Roys picture on the front reciever ring and the dial on the rear
    ring/surface and as you tighten the action screws is there if any change in the
    indicator there is some flex in the action (Not good) and skim bedding or re bedding
    will be nessary for the best accuracy potential.

    If a pillar bed is done right with the right materials it should not have any stresses in
    it.

    I use to use bedding screws to pull the action down into the stock and was allways in
    fear of applying undo stress to the action and flexing it(Even though they are very strong
    they can be flexed ) pulling the action out of true even if only a few thousandths.

    I now use spring clamps(Surgical tubing would also work) to force the action down
    it to the bedding with a little help from my self. they will supply enough force but not
    to much.

    I also bed about 1/2" to 3/4" in front of the recoil lug on long barreled rifles to balance
    the footprint and if it doesn't work/shoot well I can remove it without disturbing the
    bedding later.

    After the bedding has cured well and is cleaned up I install the action screws and start with
    35 inch pounds of torque. At the range I will increase it to see if the zero changes.(It
    should not if the bedding is right) but there is a sweet spot for torque that should be found
    and noted in the load records.

    Again; The action should not have stress if the bedding is done right. If it does it can be skim
    bedded and not tightened up to fix this. (A good place to use the surgical tubing).

    There are other ways to do a stress free bedding job and this is just what works for me.

    J E CUSTOM
     
    Last edited: Aug 26, 2010
  5. royinidaho

    royinidaho Writers Guild

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    J E,

    That's a much better method than mine.

    Next time I'll do it your way.

    Thanks
    Roy
     
  6. J E Custom

    J E Custom Well-Known Member

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    You are very welcome Roy !!!!

    I found that the action screws had enough mechanical advantage to flex the action if tightened
    very much, so this method cant flex the action.

    Good luck.

    J E CUSTOM
     
  7. BRIT

    BRIT Well-Known Member

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    Many thanks for the help. I have a magnetic base for the DTI at work so will use that.

    Thank you.

    BRIT.