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Reloaders Reference Software/Trajectory Calculator

Discussion in 'Rifle Country' started by karlborman, Jul 11, 2009.

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  1. karlborman

    karlborman Member

    Joined:
    Jan 29, 2009
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    Location:
    Central Arizona
    Hi all,

    I found an awesome tool one of you pointed me to called the Reloaders Reference. It is a software program no doubt many of you are familiar with that is freeware.

    I have a general (dumb) question if any of you know.

    In the trajectory calculator (very cool), there are a couple of things I don't understand.

    There is a parameter called SIGHT ELEVATION and it is listed as a minumum.

    There is also a RISE button and a max RISE parameter.

    There is also a PB Range that is outputs for you.

    My questions are these:

    What is the SIGHT ELEVATION? It is not the sight height, because there is another parameter for that.

    It appears you can set the SIGHT ELEVATION to anything you want.

    The max. rise parameter can be changed and there is a drop down box from 1 to 5 inches in 1/2 inch increments. I understand what the max rise is, but don't understand what the RISE and ZERO buttons do.

    If you input a end distance of less than 1000 yds. and click on the RISE button it appears to adjust the SIGHT ELEVATION figure.

    Also, what does the output term PB Range mean? It seems to be a max range of usable energy maybe??

    I know this is a super cool tool, but I just need to understand the terminology a little better I think.

    The reason I was using this calculator in the 1st place is to determine trajectory for my 270win loads. I am curious where you all zero this round at with 130g spitzer.

    Do most of you just use 25 and 200 yd as a ballpark, or if you know the best actual zero range is 238yds from a calculation, do you actually zero at that exact distance?

    Thanks guys.

    Karl
     
    Last edited: Jul 11, 2009
  2. karlborman

    karlborman Member

    Joined:
    Jan 29, 2009
    Messages:
    16
    Location:
    Central Arizona
  3. karlborman

    karlborman Member

    Joined:
    Jan 29, 2009
    Messages:
    16
    Location:
    Central Arizona
    Don't mean to sound really dumb, but I think I figured out that the sight elevation is not min for minimum, but min for minutes of angle.

    Still not sure what it all means though.
     
  4. MCMXI

    MCMXI Member

    Joined:
    Jul 1, 2008
    Messages:
    7,218
    Location:
    NW Montana
    Sounds like they mean sight elevation above the bore, but then again, you mention another input option for that? I don't understand how the input for sight elevation can "be anything". If it's as you say, then the input should be MOA, mil, IPHY etc ... but that's not exactly anything.

    That's most likely Point Blank range. Usually you'll set the target height, say 10", and the maximum point blank range means that you can aim at the center of the target from some minimum distance (yards) to some maximum distance (yards) and the bullet will land somewhere between +/- 5" (relative to the point of aim). The smaller the target height, the shorter the point blank range.

    For your .270 Win, if you were shooting Black Hills Gold 130gr Barnes Triple Shock ammunition, your PB data for a 10" high target would be high at 166 yards, low at 353 yards with a zero at 301 yards. If you go back into your ballistics program, you can enter a zero of 301 yards and then see what the bullet impact elevation is for your particular sight-in distance. In this case, you'd be 4" high at 100 yards and 4.7" high at 200 yards so you could zero your rifle for 301 yards at a 100 or 200 yard range. However, if you're able to zero at 300 yards then that might be the best way to go.

    I zero most of my rifles for 200 yards and use bullet drop data as necessary.

    :)
     
    Last edited: Jul 11, 2009
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