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How to shim a scope for more elevation?

rg666
I bought a new better quality scope for one of my high end rifles & I thought i would put the extra scope on one of my other guns since it was a higher adjustable power and a pretty decent quality scope. I have a custom Ruger 10/22 so I bought a higher set of bases to allow the 50mm scope the proper clearances but when I went to shoot the gun i ran out of upward elevation on the scopes turret adjustment when zeroing the scope at 100 yards.

Can I shim the front mount or ring to get more elevation? If so how do I go about doing this without causing torque damage to the scope? Any solutions will be appreciated.

Thanks for reading and responding to this question guys. rg
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Comments

10 comments

Date Votes
  • brier-49
    You shim the back ring.
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  • Tailgunner1954
    Assuming you have about 3 1/2" between the rings, placing a .001 shim under the rear will raise your impact point by 1 MOA. IOW if at 100yd, and your adjustments centered, your impact point is 6" low, than place a .006 shim under the rear of the scope (either under the base itself, or in the lower half of the ring).
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  • nononsense
    rg66,

    I find it hard to believe that you actually ran out of adjustments.

    Did you center the scope in the rings by bore sighting it first? If not you need to pay attention to this.

    Did you return all the adjustments to the center of the range first? Count the total number of clicks for each of the windage and elevation, divide by two and set the knobs to that number.

    You can also use a mirror in front of the objective lens with a little space for light and turn the adjustments while looking through the scope. When the double images line up you will be close to the center.

    Try this before resorting to shimming.

    Before shimming, I would look at the Burris Signature rings with alignment inserts but I don't think you'll need them.

    Best.
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  • babun
    Something is wrong here and it shouldn't need shims at 100 yards. I
    have 10moa and 20moa tactical bases on some of my sniper rifles, but that is for 500 yard and better ranges. Just for laughs, try this first....try sighting in on the lowest magnification
    first, then crank it up to the highest power. Did the grouping move?
    Are you using the factory cut 3/8" tip off grooves, or do you have some sort of aftermarket base that the rings are on? Bob
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  • tsr1965
    I had a buddy run across the same problem, but with a 3-9x40 Bushnell scope, and it was on a 10/22. The best solution is to follow the advice of Nononsense.

    The least expensive solution is to set the scope to zero as Nononsense explained, then experiment with 0.005-0.010" shimstock under the rear of the base...between the reciever and base in other words.

    If you are using that cheap extruded base that Ruger gives you for the 3/8" grooves, you are better off getting a steel Weaver/Picatinny 1913 base, and matching rings.

    Best
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  • 5mmgunguy
    Absolutely go with the Burris signature rings. You can get an additional 20 moa at 100 yards with these rings, they are great! The shimming will work but can put unnecessary stress on the scope tube.
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  • Herschel
    A suggestion. Get a one piece base and shim under it as they did with the 1903A4 Rifles. Putting a shim under a base or ring on two piece bases can put torque on the scope tube.
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  • timhill100
    hers a good link on how to shim a scope
    http://www.gatewaytoairguns.com/library/Scope Shim Guide.htm
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  • asphalt cowboy
    As others have said, try re-centering the reticule first.
    There's a simple way to do that without counting turret clicks or revolutions.
    Take a cardboard box narrow enough for your scope to lay clear across it. Cut V notches one on each side of the box for the scope to lay into and secure the box to a table with either tape or something heavy inside it. Next tape a piece of graph paper to something far enough from the scope that it can be focused on the lines on the paper. Nothing needs to be level since you're going to be turning the scope anyway.
    Place the scope Up-side down in the notches and level the elevation cross hair with the nearest line and mark that line on the paper. Next turn the scope 180 degrees and again level it with the nearest line and mark it. Find mid-point between the two lines and mark that.
    Now simply turn the elevation cross hair down to match that line.
    The same can be done with the windage except you lay it with the windage turret down and then turn it 180 degrees.
    I've had best results using 1/8 inch grid graph paper at anywhere from twenty to fifty feet.

    This is by no means 1000 yards precise, but it should get you plenty close to a starting base line.

    If you still find that shimming is necessary Brownells carries Proper base shim sets. The shims are tapered and used in matching pairs so as not to place your scope tube in a bind.
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  • givette
    Hey, A/C..excellent! I was able to follow your post in my mind! I have an old wooden cigar-box, and I'm gonna v-notch it! You 'da man!!

    Best, Joe
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