discrepancy between Zeiss BDC and ballistics calculator

Discussion in 'Long Range Scopes and Other Optics' started by dmax1800, Aug 21, 2015.

  1. dmax1800

    dmax1800 Well-Known Member

    May 8, 2013
    I'm wondering if anyone else is having an issue with their Zeiss scope. I have an HD5 5-25x50 with a Z-800 BDC reticle. Zeiss has a ballistics calculator that supposedly gives the appropriate magnification for the hash marks at the various ranges. Given my bullet weight, velocity, BC, altitude, temperature, etc, the calculator says to use 21.5 power on the scope. I have to reduce the power to 18.5 to get the first hash mark to be on target at 300 yards when the cross hairs are zeroed at 200 yards. I could see changing the magnification 1/2 or 1 power, but 3 seems a little much.

    Has anyone else had this problem, or has anyone had their scope be real close to the calculator?

    For anyone that is going to ask, here are the details. 300 Win mag, 180 grain Nosler Accubond (published BC of .507 and a certain ballistics calculator that uses .492), velocity 3045 fps, scope 1.875" above the bore, 1000 feet altitude, 60 degrees.

    I've tried lowering the BC and the velocity, but I'm still 2 power levels away from the calculated power level. I've talked to Zeiss, and they don't have an answer.