CZ 550 Scope Mounting vertical problems

Discussion in 'Gunsmithing' started by benchracer, Dec 22, 2013.

  1. benchracer

    benchracer Well-Known Member

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    I have a CZ550 Safari Magnum that I have recently mounted a Zeiss Conquest 4.5-14x44 AO scope on using Warne Quick Detach Rings. The CZ 550 uses a 19mm dovetail as the mounting surface for the rings.

    When zeroing the rifle @ 100 yards, I am running out of up travel WAY before I can get to a 100 yard dead-on POI. According to my calculations, it would take about 16 MOA to reach my 100 yard POI and another 15-20 MOA to get me back to being somewhere near the center of the scope's vertical adjustment range.

    Where should I be looking to find the source of misalignment? I would think that the integral dovetail would be visibly mis-machined in order for it to be off by 30+ MOA or so. Ditto the scope rings. I have considered having the action drilled and tapped for a picatinny rail, but I am not sure if that would solve the alignment problem and I don't want the scope mounted any higher above the bore.

    Is this something a competent smith can easily find and correct?
     
    Last edited: Dec 22, 2013
  2. threejones

    threejones Well-Known Member

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    I'm sure you've already tried this, but I'll throw it out there anyway. Have you tried swapping the rings front to back. I had a set of rings that were noticeably different heights. It was a pain at first, but once I figured it out it saved me buying a 20 MOA pic rail (sorta:D)
     

  3. FEENIX

    FEENIX Well-Known Member

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    I don't want to assume anything but are the rings the same height? For instance, Ruger M77 MKIIs have two different size ring heights; you put them backwards you'll have similar problem you're describing.

    [​IMG]

    Just a thought for your consideration.
     
  4. FEENIX

    FEENIX Well-Known Member

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    OOPS, you beat me to it as I was typing my response.:rolleyes:
     
  5. benchracer

    benchracer Well-Known Member

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    On a CZ550, the rear ring has a "recoil lug" that engages a slot in the receiver. The front ring has no lug. It is not possible to reverse the two. I suppose it is possible that the front and rear rings are mismatched in height, but I would think that the misalignment would be pretty obvious when trying to tighten the ring halves together.
     
  6. bruce_ventura

    bruce_ventura Well-Known Member

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    I had a similar problem when installing a scope on that model CZ rifle chambered in .375 H&H. After optically zeroing the rifle, the impacts were about 20" low at 100 yds, hitting dirt in front of the target. It was difficult to even see the impacts because there was so much dust kicked up. I was using CZ rings. Luckily for the customer, the scope had barely enough adjustment get to a 100 yd zero.

    I concluded the problem was barrel vibration. The stock was solid and the impacts were in similar locations for two different shooters. I'll bet your rifle has the same issue.

    I would normally recommend that you use Burris Signature rings with offset inserts, but I don't think they are available for the CZ long action. Next, I recommend that you change ammunition. Barrel vibration of this magnitude will vary a lot between different loads. Failing that, you could bed the scope in the rings to add about 20 MOA of elevation. See YouTube videos on this subject. Place a 0.032" spacer in the bottom of the rear ring and embed it in bedding material.
     
  7. benchracer

    benchracer Well-Known Member

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    The point of impact issue is occurring during load development, so I am not sure changing ammunition is the answer. However, bedding the scope in the rings sounds like that would be a viable fix. If that solution were employed, I am guessing that the rings would need to be lapped and that bedding of the front and rear ring would be required to accommodate the new angle of the scope tube. Is that right?

    I will probably consult a good smith to do the work, but now I at least can hold an intelligent conversation regarding the fix for the problem. Thank you for your insight.
     
  8. bruce_ventura

    bruce_ventura Well-Known Member

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    I think lapping would take too much time. I would bed both the front and rear rings.
     
  9. benchracer

    benchracer Well-Known Member

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    I had expected that lapping would have to be done to allow for the change in vertical cant of the scope tube. If simply bedding the front and rear rings would do the trick, so much the better...
     
  10. FEENIX

    FEENIX Well-Known Member

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    It's old (not sure what the OP's final fix) but found this FYSA ...

    (CZ 550 American Safari Magnum | Outdoor Life)

    Good luck!
     
  11. benchracer

    benchracer Well-Known Member

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    VERY useful thread and a good find. Thank you!
     
  12. bruce_ventura

    bruce_ventura Well-Known Member

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    Every time I've seen someone try to correct an elevation problem using a shim underneath the scope tube, the results were bad for the scope. The shim reduces the contact are between the ring saddle and scope tube. Tightening the ring screws puts dents in the scope tube. Because the contact area is low, the scope slips in the rings when the gun is fired, causing gouges in the tube.

    Shims alone are not a good approach for a magnum rifle. Bedding the scope tube with a spacer in the bedding material works just fine.