question about useable turret travel

Discussion in 'Long Range Scopes and Other Optics' started by davewilson, Aug 7, 2005.

  1. davewilson

    davewilson Well-Known Member

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    i've heard some refer to the end of turret travel as a place you might not want to be.i want to mount my scope at the most angle that i can get away with,but still have good,repeatable function of the scope.should i stay 1/4 turn or a 1/2 turn away from the end of travel in my verticle turret? is there a general rule of thumb? i have a 6-20 lupy that seems to have 60 moa if that makes any difference.
     
  2. Mike in Texas

    Mike in Texas Well-Known Member

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    There are a couple of issues concerning internal usable travel.

    1st there's the issue with windage. If the erector tube ( that thing in the middle that moves when you adjust the scope) is in the center as far as windage is concerned, then the elevation adjustment can be used to its full extent top to bottom.

    If you have some windage dialed in, as from sighting in your rifle, the erector tube may not be in the center of the outer tube, and as you get near the top or bottom of the adjustment, the erector may contact the outer tube. When this happens, the adjustment may still turn but the erector is mechanically captured and no adjustment takes place.

    The next thing is a weak erector tube spring, or an overly long or thick spring.
    A weak spring shows as inconsistant elevation adjustment as you near the upper limit of travel, or as a wandering point of impact on an otherwise stable rifle/bullet combination.

    An overly thick spring shows as an inability to get to a 100 yard zero; you're point of impact may be several inches too high at 100 yards for example.

    Hope this long winded expanation made some sense.

    Mike ,Granbury, Tx
     

  3. riof16

    riof16 Active Member

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    So, on the same issue, if I want to restore a scope to middle-zero on both axis that I do not know how far it has been turned, how would I do that?
     
  4. davewilson

    davewilson Well-Known Member

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    HC,i'm familiar with all of that,but what i'm asking is for a rule of thumb as to how far to try and stay away from the end of (centered) travel.i'm gonna send the scope to one of these guys that make the turrets accurately repeatable.
     
  5. Mike in Texas

    Mike in Texas Well-Known Member

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    Dave,

    I don't know of a rule of thumb fopr that. I take mine out and track them, but have never been in a position to have to use the last 1 or 2 clicks.

    Can;t see any reason other than spring load into or away from the spring that one would need to be concerned about.

    Lafe,

    if you have something like a shoe box, cut a V notch in each side, lay the scope in it and rotate while looking at the reticle .

    Adjust the elev and windage until the reticle center stops occilating.

    Took longer to explain than to do.
     
  6. riof16

    riof16 Active Member

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    HOOD, it took me a minute to visualize the "V in a shoe box", but I got it. Who would have ever thought of that! I will give it a try, thanks.

    DAVE, sorry to sort of go a little off subject on your post.
     
  7. hareng

    hareng Well-Known Member

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    Its called optically centring the scope.

    If you have access to a vice or clamping arrangement, adjust the elevation whilst looking through the scope, you should see the ret move. A bore sight will come in handy.
     
  8. davewilson

    davewilson Well-Known Member

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    Lafe, just turn the turrets until they are in the middle of their travel.should be very close to centered.
     
  9. Chrismadrid

    Chrismadrid Well-Known Member

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    Here's a QUICK way to optically centre - But not 100%.
    1)Remove scope from gun.
    2)Put on LOWEST mag value.
    3) Place the objective againsta a mirror that is WELL lit.
    4) You should (with 2nd FP anyway) see TWO reticles - the real one and a shadow.
    5) Twiddle with knobs until they more or less align - I say more or less as I've never managed a 100% overlap.

    But V-Blocks is NO DOUBT AT ALL better.