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Thread: Scope Height. Help needed

  1. #1
    Boolit Master
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    Scope Height. Help needed

    I cannot lower the poi with two different scopes on a Rem 700 MTN rifle. I am currently using high rings. From what I can find I could go to medium ring and still have enough clearance for 50mm ocular bell. The difference in height is .070". Can any one calculate how much that would me @ 100 yards?

    Thanks for your help
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

  2. #2
    Boolit Master pietro's Avatar
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    .

    FWIW

    I've found that some scopes have un-equal windage & elevation adjustment ranges, and have often been able to zero a rifle via simply rotating the scope in the rings counter-clockwise (as you look through the scope), making the old windage turret the new elevation adjustment and the old elevation turret the new windage adjustment.

    The method works with crosshair or dot reticles, though not so much with a post reticle.

    .
    Experience is a wonderful thing - It lets you recognize a mistake, when you make it again.

  3. #3
    Boolit Grand Master
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    Themoose, you are talking about two different issues, Scope offset (the physical distance the scope is mounted above the receiver) AND the ability to sight the scope to match a particular load and a particular range.

    When the scope is mounted directly over the bore (as opposed to a mount to one side or the other) the offset has very little affect on P.O.A. and P.O.I. at all but very close ranges. That vertical offset will play a role in P.O.I at extremely close ranges but becomes a non-issue at longer ranges.

    The inability to sight a scope in is more likely due to a difference in height between the front and rear rings than it is to the overall height of the rings. You may have rings or bases or both, that are not equal in height.
    At very long ranges some scopes lack enough adjustment to sight the scope at the maximum range of the shooting. In these cases the entire scope may tilted to provide the needed adjustment range. You may have the opposite problem of a lack of adjustment to sight the scope at extreme close ranges.
    You always want the scope as close to the bore as possible. This is generally dictated by the size of the objective lens (front lens) but sometime the ocular lens (eye piece) will dictate the mounting height.

    If you've "run out" of adjustment and cannot sight the scope in to match the P.O.I., the overall offset is probably not the factor in play.

  4. #4
    Boolit Grand Master

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    As said simply raising or lowering the scope at level probably wont do the trick here. Look for base with 10-20 mins built into it of elevation. This will set the scope at a slight angle downward.

  5. #5
    Boolit Master
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    I don't need to raise elevation, I need to loser it
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

  6. #6
    Boolit Master
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    Burris makes some rings that can adjust elevation dependant on the insert used. I have some on a rifle that had your issue. Worked great. Posalign system, I think.
    Last edited by high standard 40; 02-23-2020 at 02:40 PM.

  7. #7
    Boolit Master

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    Put a shim under the rear of the scope between the bottom of the scope and the top of the lower half of the ring. Depending on how much adjustment is needed and how thick your shim material is, you may need more than one shim. A piece of a worn out hacksaw blade with the teeth ground off and curved works well. Millett Sights also makes adjustable scope rings.

    DG

  8. #8
    Boolit Master
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    Remington 700 receivers tend to be too high in the back. Either the receiver warps in heat treat or the bridge is left too high.

    You can have the rear base machined down, use a shim under the front base or use the Burrise Offset Signature rings.

    The first thing you do is get your scope reticle in the tube. You can do this by cutting V notches in a shoe box. Then put the scope in the box and aim it out the back door at a distant object. Adjust the scope and rotate it while looking through it. Keep adjusting until the cross hairs do not move when the scope is rotated.

    Then install on the rifle with the offset rings and fire a few shots at 25 yards.
    Install a Plus insert and a minus insert of the same value in on ring to adjust the point of impact.

    It is possible to calculate the offsets needed with trigonometry but I cannot teach you trig here.

    If you want to PM me with your error I can do the trig for you.

    Need the error at your target in inches before you try to adjust your scope.
    The distance to the target in inches
    Need the distance between the rings in inches.
    Then I can calculate the amount one ring or one end of the base needs to be offset.
    EDG

  9. #9
    Boolit Master
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    Thanks to all of you. I will recheck optical center and try to get to range in next two days..thanks agay
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

  10. #10
    Boolit Master


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    Quote Originally Posted by high standard 40 View Post
    Burris makes some rings that can adjust elevation dependant on the insert used. I have some on a rifle that had your issue. Worked great. Posalign system, I think.
    This is the best way I have found for centering a scope on target without using shims. I have installed these rings and inserts on numerous rifles with excellent results.
    I first center the cross-hairs then use the various inserts to mount the scope as close as possible to the bullseye.

  11. #11
    Boolit Master pietro's Avatar
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    Quote Originally Posted by Der Gebirgsjager View Post

    Put a shim under the rear of the scope between the bottom of the scope and the top of the lower half of the ring.

    Raising a scope, whether via a shim or something else, will raise the POI even further than the OP is complaining of as being already too high.


    .
    Experience is a wonderful thing - It lets you recognize a mistake, when you make it again.

  12. #12
    Boolit Master

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    Well, maybe I misunderstood him, but he said, "I can't lower the poi..." which to me means that his elevation is set as low as it will go as presently mounted, and he's still hitting low. So, if you raise the back of the scope it will be pointing lower, will it not and the poi should be lower. If this isn't the case, then the question needs to be stated more clearly.
    If you want it to shoot higher you shim the front ring.

  13. #13
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    Hi Der Gebirgsjager. I believe you have it backwards. You shim the rear to increase elevation (POI,) and shim the front to decrease elevation (POI.) If you raise the rear of the scope, you are lowering the point of aim (POA.) When you bring the point of aim back onto the target, the barrel will be pointed higher, thereby increasing the POI. If you want to lower the POI, you need to raise the POA by shimming the front to bring the barrel down. Exactly like you would when adjusting the front sight of a rifle or pistol with iron sights.
    Ed
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  14. #14
    Boolit Master
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    The solution to the error at 100 yards (3600 inches) is found by ratios

    for example

    .010 shim thickness under one end of the mount/ the distance between the mount bases = vertical error/3600 inches


    for 4 inches between the bases like a short action the error is 9 inches at 100 yards
    for 5 inches between the bases like a long action the error is 7.2 inches at 100 yards

    Both of the above assume a .010 shim or offset with the Burris Posalign rings.
    If you have less error use a .005 offset for half as much error

    If you have more use .015 or even .020
    If you have a lot like 2 or 3 feet you might need offset upwards in one ring and down wards in the other.
    EDG

  15. #15
    Boolit Master
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    For clarification, I am unable to adjust the elevation low enough to zero it, or the rifle shoots to high
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

  16. #16
    Boolit Grand Master



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    These rings will do what you need without stressing the scope. https://www.burrisoptics.com/signature-rings

    This has a space and shim chart to show you what you need. https://www.burrisoptics.com/sites/d...nstruction.pdf

    Unless you are using taper mounts the scope rings should be parallel the the bore and ring height will not effect the ability to adjust the scope. Scope ring height will affect the two point that the bullet crosses the line of sight.

    The other option is shimming the bases or using tapered based. Not sure if you can find reverse taper bases.
    Last edited by M-Tecs; 02-23-2020 at 10:19 PM.
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  17. #17
    Boolit Master

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    Quote Originally Posted by redleged View Post
    hi der gebirgsjager. I believe you have it backwards. You shim the rear to increase elevation (poi,) and shim the front to decrease elevation (poi.) if you raise the rear of the scope, you are lowering the point of aim (poa.) when you bring the point of aim back onto the target, the barrel will be pointed higher, thereby increasing the poi. If you want to lower the poi, you need to raise the poa by shimming the front to bring the barrel down. Exactly like you would when adjusting the front sight of a rifle or pistol with iron sights.
    Ed
    o.k. -- you are right -- I am wrong. Still, shimming the front scope ring should work.
    Last edited by Der Gebirgsjager; 02-23-2020 at 11:07 PM.

  18. #18
    Boolit Master
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    I have used the Burris rings to fix a rifle that the front and rear mounting holes were not drilled in line with each other. They work great for fixing alignment problems.

  19. #19
    Boolit Master

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    I'm not fan of shimming scope bases. once you do the two rings are not concentric, and a good chance you will warp or bend the scope. Even when the rings are seemingly concentric I usually lap the rings to assure there is no stress on the scope.
    It may help to know what brand rings and bases as well as what scope brand the original poster is using? Is the scope proven on another rifle?
    Good Luck,
    Rick

  20. #20
    Boolit Master
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    I have a Rem 700 MTN rifle, using Weaver two piece bases(35 &36) Badger 30mm rings. Two scopes were used previously on other rifles. One a Weaver the other Konus. I have tried to optically center both scopes, as suggested. Yesterday I bore sighted rifle @ approx 80 yds with the Weaver and was not able to zero the Konus(same issue as before).. Will just go with Weaver and find another use for Konus or try to get it repaired under warranty. Thanks to all for sharing your thoughts.
    Perhaps my learning skills have diminished in my senior years.. 50 years ago I could read something once and then "have it"... Now I read it about three times, do it a couple of times and then... "have it" only about half the time.

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