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Thread: Picatinny rail modification.

  1. #1
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    Picatinny rail modification.

    Over the weekend we were down Tekapo shooting long range gongs. It was discovered at just over 1250m my brothers scope ran out of elevation. On investigating the turret there was with a 100m zero 35moa below the zero. No wonder the top end was limited. He is running a 20moa picatinny so needs a 40moa which are not common for a Tikka T3 Varmint. So he will probably get the rail machined. The question is with the rail at 139.50mm long how much should be removed from the front to get another 20moa?
    Thanks to those with different brain to me.
    Jeremy

  2. #2
    Member 300_BLK's Avatar
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    200 thou?

    just fold up coke cans till you have enough shims bro... then test and adjust...Chur!
    tetawa and mikee like this.
    Warm Barrels!

  3. #3
    By Popular Demand gimp's Avatar
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    whatever the difference between back and front is currently, again?

  4. #4
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    Or get the Burris rings with offset inserts.
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    There are only three types of people in this world. Those that can count, and those that can't!

  5. #5
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    You guys are a hoot, so #1 not really scientific enough but might work #2 current difference in thickness is about 0.030 so again would work if there was nothing else in play say the receiver not totally inline with the bore. #3 trying not to spend more hard earned money on hardware. But hey keep the suggestions coming someone might chance on the correct answer I just wont know it when I see it.

  6. #6
    DPT
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    If you skim the bottom of the rail at an angle the screw holes will no longer be at right angles to the base of the rail.
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  7. #7
    DPT
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    You know at 100 yards 20moa is 20inches so just calculate it back to 139.50mm
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  8. #8
    Sending it Gibo's Avatar
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  9. #9
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    Pie - thag - o - rus

    Difference in thickness front to back of existing 20 rail times 2. And need to remove front and back, or otherwise you'll torque the rail.

    Should work...... maybe...... sort of..... of course it will...... hold my beer and watch this
    Please excuse spelling, as finger speed is sometimes behind brain spped........ Or maybe the other wayy.....

  10. #10
    Member gadgetman's Avatar
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    Quote Originally Posted by DPT View Post
    If you skim the bottom of the rail at an angle the screw holes will no longer be at right angles to the base of the rail.
    That will be insignificant when you consider the angles and tolerances of the threads and holes.
    There are only three types of people in this world. Those that can count, and those that can't!

  11. #11
    Member gadgetman's Avatar
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    Quote Originally Posted by DPT View Post
    You know at 100 yards 20moa is 20inches so just calculate it back to 139.50mm
    139.5 * 20.94/(36*100) = 0.811mm
    There are only three types of people in this world. Those that can count, and those that can't!

  12. #12
    Member rossi.45's Avatar
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    send the rail to Waitaki Engineering and get it done properly . . they did a 45MOA rail for me, fast and resonable price

    i would also get Burris XTR rings with offsets, youll get another 40MOA

    R.
    without a picture . .. it never happened !

  13. #13
    Member 300_BLK's Avatar
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    Coke-can-a-rus just shim it till it is where it needs to be...
    Warm Barrels!

  14. #14
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    Loctite liquid metal (or similar tapable epoxy liquid metal there are a few) to form the perfect tapered shim at both ends, with a small piece of 0.030" shim stock under the rear to set the correct height. A small piece of shim stock, 4x2mm or thereabouts (you don't want the rear mount base pivotting on one end of the shim - a small dap of superfix to hold it in the right place). Same process as setting up a rail where the machining isn't quite perfect. Thank me later...
    gadgetman and kimjon like this.

  15. #15
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    Thanks for the info guys. The rail is at the machine shop getting a 0.035 skim so that should fix it. That it will then make it about 40moa total

    Jeremy

 

 

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