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Scope Mounting Problems

Discussion in 'Long Gun Accessories and Optics' started by Morrey, Oct 24, 2016.

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  1. Morrey

    Morrey Member

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    I am mounting a Zeiss 3-12x50 30 mm tube on a Weatherby Vanguard Wilderness, 30-06.

    I bought a Leopold STD 2 pc base set and Leupold rings with the front extended ring. W/O this extension turned backwards, I'd not be able to get the scope far enough back for a proper check weld.

    I am using an analog Bushnell boresighter to sight in before range tests. I always set the scope's adjustments to mid-scale prior to mounting. Windage is easily adjusted with the rear screws. Problem is I have run out of vertical adjustment with the POI shooting too low. I cut two shims from a soda can and laid them in the bottom of the back ring. It has brought my POI up adequately. BUT......Is this a wise practice to do this and put pressure on the scope's tube?

    I am looking to fix this in a better fashion. My thoughts for options:

    *Replace rings. Does Burris make an insert capable ring that is extended that will work with Leupold bases? This would be an easy fix if this configuration is possible.

    *Remove some material off the front base. I don't have any professional milling machines, just a Dremel tool with assorted grinding stones and polishers. Material removal is sort of a "guess" w/o better equipment.

    *Put a shim under the rear base. I have never done this so I am not sure how to go about it.

    *Take to gunsmith and have it done professionally. Probably be at least $80, maybe more.

    Thanks for suggestions!!!
     
  2. rjrivero

    rjrivero Member

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    You could easily lap the front base a few thousandths. Cover the front receiver with masking tape, lay wet to dry sandpaper over the tape and rub the base on the sandpaper nice and slowly until you take off enough material to make the difference you need.

    You could also just ditch the two piece and get a 20moa base to mount your rings to.

    I'm not a big fan of shims. Simple mechanisms are always better, IMVHO.
     
  3. entropy

    entropy Member

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    It is always better to shim the rear base instead of the rear ring. It is simple to do: Get an aluminum can, cut pieces to match the bottom of the base, drill mount holes, mount. Problem solved. rjrivero's method works even better, but is irreversable. If you want to use those rings for another scope, or another mount, it may not work, whereas you can just pull the shims out if need be.
     
    Last edited: Oct 24, 2016
  4. Morrey

    Morrey Member

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    I'll agree that shimming the bed of the ring may lead to scope problems. The most straightforward fix is the shim under the rear base so the base could be transferred to another rifle. RJRivero's fix which is something I am strongly considering too.

    I have a question about lapping the front base. If I mic the base as is, am I targeting a specific amount of material removal? Would I want to remove 8/1,000 which if I am not mistaken, is the thickness of two strips of soda can material (4/1,000 ea) which is what I have now in the rear ring? If I have a removal goal, this would help me hit the target w/o mounting and remounting the scope just to see if I am close. What is my best approach since I surely don't want to overshoot my mark.
     
  5. jmr40

    jmr40 Member

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    If it were me I'd not use any scope with a 50mm objecitve. The negatives far outweigh the positives. And you couldn't pay me to use those mounts, they are about the last choice and should only be used if the mounting holes on the receiver are drilled so poorly that you can't get the scopes windage zeroed. But since you already have the scope the best bet is to make it work with some proper mounts. This is what I'd buy.

    http://swfa.com/DNZ-Game-Reaper-30mm-Scopemount-P41268.aspx
     
  6. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

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    could the rings or mounts themselves be out of spec? I blamed my 700 for messed up mount holes for years before finding out the base i was using were very slightly off.
     
  7. Morrey

    Morrey Member

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    I'd say the rings/bases are at fault based on what has happened. I started with Talley integral base rings and ran out of windage adjustment to the right before it got to zero. I was not sure what was out of alignment so I took them off and put on Leupold STD bases and ext rings knowing this rear windage system would take care of horizontal mis-alignments. Lo and behold I ran out of vertical adjustment with these rings. What???

    I switched (rotated back to front) the front base around but no change. I realize I could have lapped the front Leo base down, but I opted to shim up the rear under the base. It now zeroes perfectly at mid-scale scope setting, so all I have to do next is take it to the range for some test firing. I am using an old school Bushnell analog bore sighter I have used for years. I made sure my bore arbor was adjusted correctly and even tested it on a 30-06 that I know the zero is right...it was dead on.

    This all leads me to think that both scope bases are somewhat misaligned. The Talley was off horizontally and the Leo was off vertically. I am scratching my head over this one even though I think my problem may be solved with the rear shims. Has manufacturing technology precision gone to the dogs? I have mounted many dozens of scopes in my time, and this one threw me a curve ball.
     
    Last edited: Oct 25, 2016
  8. cdb1

    cdb1 Member

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    I will only shim a one piece base, never a two piece. Shimming a two piece base puts stress on the scope tube whereas it doesn't with a one piece.

    Though I prefer the looks of two piece bases I'm slowly switching my rifles over to one piece picatinny's. I mount scopes at work and have my own scope mounting business. Scope tube lengths today are all over the board and quite often there is trouble mounting scopes with two piece bases, even with extensions.

    With a picatinny you will never have a problem mounting a scope and setting it to your eye relief.

    When using two piece bases I prefer Warne over Leupold because if you need to extensions, with Warne you purchase extended bases instead of extended rings. We have three Vanguards in the family that all required extended bases to mount scopes properly. Haven't bought new scopes for any of the Vanguards since I switched to picatinny's but when I do I'll get picatinny's for the Vanguard's.

    Good Luck.
     
    Morrey likes this.
  9. lobo9er

    lobo9er Member

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    ....
     
    Last edited: Oct 26, 2016
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