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barrel indexing and target ??????

Forums General Discussion barrel indexing and target ??????

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    miatamama
    Participant
    Member
    United States
    Accuracy: +1

    Hi!   I have a question  about barrel indexing.       I sight my airgun at 10 meters.    It doesnt vary hole on hole at 33 ft. But when I go to the club and shoot at 30 yards it shoots 1/4 inch to the left I bring it home and it is dead on. So my question is  Do I have to index my barrel?            If I re adjust for 30 yards to be hole on hole it is off when i shoot at home.

    Second question      Does anyone have multiple turkey silouete on one sheet?    We are starting to shoot indoors on the 24th and would like to print the targets with turkeys instead of bulls or dots.       JCS     miatamama

                   

     

     

     

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    nervoustrig
    Participant
    Member
    United States
    Accuracy: +111

    Sounds like a classic canting problem.  Either the scope is misaligned to the bore, or the gun is being held canted when shooting.  See this thread for a DIY approach that works to eliminate both potential sources of error.
     
    https://www.airgunnation.com/topic/best-way-to-level-a-scope-2/#post-1003404

    Indexing has a different purpose.  It is to orient the barrel in a manner that is most favorable to its vibration (harmonic) characteristics.  The goal being to improve average group size, not correct a divergent POI.

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    biohazardman
    Participant
    Member
    United States
    Accuracy: +81

    So, set it at thirty yards and then bring it home to see if it is off or not.  Just an idea that may save you some time.  It's also quite possible that your eye is in a different spot on yer gun, especially if the benches or table you sit at are at slightly different heights, so it may be a parallax thing as well. 

    Otherwise,  I would have to agree with nervoustrig.

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    elh0102
    Participant
    Member
    United States
    Accuracy: +55

    It could be a canting issue, as mentioned. Or, it could also be just one of those weird things. I have rifles that will vary slightly in the windage adjustment at different distances, don't know why. I assume it is related to the rotation of the pellet, which might result in a variation on either side of the POA. I don't think it's a canting result in this instance, as I've observed it with the rifle set up level on the bench. Go figure.

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    miatamama
    Participant
    Member
    United States
    Accuracy: +1

    Biohazardman,    Yes it does just the opposite if sighted at 30 yards. when i bring it home and shoot at 10 yards. I dont think it is cant but may be. I will remount the scope and try again.      JCS

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    miatamama
    Participant
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    United States
    Accuracy: +1

    nervoustrig,     I am still reading your tutorials.    Thanks

     

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    SqrlHntr
    Participant
    Member
    United States
    Accuracy: +5

    This might help some too.

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    miatamama
    Participant
    Member
    United States
    Accuracy: +1

    Thanks to everyone who tried to help me. I have learned alot on cants. I think i found the trouble. I used the plumbbob and found a slight bit of scope cant. Every mount screw was not even finger tight,  all eight. I lined it up and tightened it back up and re zeroed. It is right on now and will try the further distances at the range next week.   If not on at both distances i will come back for more help.    Thanks   JCS

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    JW652
    Participant
    Member
    United States
    Accuracy: +8

    SH – Thank you for covering all the variables. Best info on cant that I have ever seen. My tongue gets tied in knots trying to verbalize the results that you illustrate.

    Brilliant!

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    nervoustrig
    Participant
    Member
    United States
    Accuracy: +111

    FYI, that is Scott Hull’s illustration…scotchmo on the forums.  It is indeed a very nice reference.  

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    SqrlHntr
    Participant
    Member
    United States
    Accuracy: +5

    nervoustrig

    FYI, that is Scott Hull’s illustration…scotchmo on the forums.  It is indeed a very nice reference.  

    Could not remember where I found that or who to credit for the pic, but it was a keeper for sure. Thanks! 

    • This reply was modified 2 months ago by SqrlHntr.
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    kernbigo
    Participant
    Member
    United States
    Accuracy: +1

    add a bubble level 2 the scope

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    douger
    Participant
    Member
    United States
    Accuracy: +52

    x1 on the bubble on the scope best place to put it 

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    Airgun-hobbyist
    Participant
    Member
    United States
    Accuracy: +21

    kernbigo

    add a bubble level 2 the scope

    douger

    x1 on the bubble on the scope best place to put it 

    I run a plumb line from the ceiling and align the cross hairs to the scope mounted bubble level.  For an additional step before mounting on a rifle, the scope is mounted to an eBay special picatinny rail screwed to a solid bench to verify that it tracks strait up and down the plumb line after installing the bubble level.  I read that even high-end scopes can track in a diagonal if built wrong.  Then I mount it to the rifle and check for bore and shooting cant.

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