measuring scope height using canted bases

Discussion in 'Long Range Hunting & Shooting' started by Frogman77, May 19, 2009.

  1. Frogman77

    Frogman77 Well-Known Member

    Feb 1, 2009
    Does anyone know how to measure the scope height above boreline using canted bases??? do you use the back end of the scope where it sits higher above boreline or towards the objective where it's closer???

    Just as an example, on my 17hmr if I measure from the objective it's 1.5" above bore. If I measure from the center of the scope it's 1.8" and If I measure from the rear it's 1.97"

    my data from shooting from 25 40 50 and 100 yards plugging into trajectory software prints closer when using 1.97"

    is there a correct formula or method to properly measuring scope height when using canted bases??

    thanks in advance!!
  2. Seven Oaks

    Seven Oaks Well-Known Member

    May 10, 2009
    You may have to go to the range to confirm which measurement to use. A friend of mine had the same issue. Not going to make alot of difference until you get out there a ways. On his gun, with a 200 yd sight in, the ballistics program said to add 17 clicks to be on at 400 yds. with both scope height measurements. So it took quite a distance on that rifle before any discrepency showed up in the program using the 2 heights. Of course, when this will happen will depend on the trajectory of the round you are shooting.

    I would plug in the higher, print off the data for the middle and lower number and go shoot and see what matches up.

    Unfortunately, this looks like a case of having to tell the ballistics program what to do instead of the other way around....

    Hopefuly somebody can give you a more useful answer than this. I just know we went and shot my buddies 7WSM to make sure and settled on the middle measurement at the scope .


    Last edited: May 19, 2009