Scope Adjustment, Range, and Scope Bases

Discussion in 'Long Range Scopes and Other Optics' started by 270 MKV, Sep 26, 2012.

  1. 270 MKV

    270 MKV Well-Known Member

    Messages:
    95
    Joined:
    Aug 21, 2012
    ok...I know this one has been most likely beaten to death, but I have a question.

    My Scope has an advertised 30 mil total adjustment...so. 15 available from center.

    the max load I may play with could reach 1400 yards for punching paper...IFF I can even hit the broad side of a barn...and IFF I was crazy enough to play in some Trans Sonic Soup...and IFF God smiled on the shot...

    so, at that range, I would in theory need 14 mills of scope adjustment....

    so, here is the question...


    at what point does the scoped adjustment become unreliable with respect to adjustment range??? Take for instance a torque wrench...available reliable adjustment is between 1/4 and 7/8 full scale...if I applied the same principle to a scope, then that 30 mill total becomes...22.5 mills.

    So, reliable travel from center is now 11.25 mils...still plenty in theory to get me to ~1200 yards.

    adding a 20 MOA Base to the mix gives me a buffer of almost 5.4 mils..added to the self limited reliable travel of 11.25...gives 16 mills of reliable scope travel...obviously more than the riffle needs.

    so, what have some of you done???

    what is considered the reliable limit on scope adjustment??
     
  2. bruce_ventura

    bruce_ventura Well-Known Member

    Messages:
    1,106
    Joined:
    May 22, 2011
    On a decent quality scope, the elevation adjustment should be reliable out to a click or two short of the limit stop. This is a micrometer device, after all. It should be linear from one limit to the other. On low quality scopes, the reticle may stop moving before the limit is reached.

    Keep in mind that your standard base may not be parallel to the bore. The barrel could be bent, the barrel could be installed crooked in the receiver, or the receiver or mounting rail could have other dimensional variations that could affect the alignment of the rail. Expect up to 3 mils of misalignment in any direction on a production rifle. Some are even worse.

    FYI, you could also use Burris Signature rings to add up to 2.5 mils (30 mm rings) or 5 mils (1" rings) of adjustment. Signature rings will allow you to correct mount misalignment errors in any direction.
     

  3. 270 MKV

    270 MKV Well-Known Member

    Messages:
    95
    Joined:
    Aug 21, 2012
    ok, so allow for at least 5 mils of manufacturing tolerance stack up!!


    looks like the 20 MOA base will allow for some relief..but possibly add more error..

    gun)