Shooting on Angles (again)

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Dave King, Aug 10, 2001.

  1. Dave King

    Dave King Well-Known Member

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    May 3, 2001
    I was reading on Sniper Country and came across a post from a fella I know. His question was about shooting on angles and that got me thinking about the process. Here's a reply/query I posted there, maybe we can discuss this here!!


    (We're generally discussing 308 Win class rifles on that site so the data is for the 308 and 2700 fps.)


    Needed...Rocket Scientist

    The post about shooting at angles opened a small can of worms for me.

    I know about the Slope Doper and the MilDot Master and cosines but...

    I was going to answer the questions posted by Ray and Kevin (Andy's Dad) when I came upon a quandry.

    How do I adjust my 100 yard zero to accomodate the angle component?

    Here's how I got confused.

    200 yards at a 60 degree slope, cosine of 60 is .5, 200 times .5 equals 100, so use the 100 yard setting. Seems simple enough so far.

    My 100 yard zero is based on a zero angle shot, my scope is mounted 1.5 inches above the bore and the drop for the first 100 yards of travel of the bullet is 2.309 MOA. I add these two together to get 3.742 MOA of apparent drop at 100 yards for my zero angle zero.

    In this example we're shooting at 60 degrees (cosine .5) so the 2.309 MOA of drop experienced by my round in the first 100 yards of travel should become 1.155 MOA (50 yards of gravity). This 1.155 MOA changes my 100 yard zero and now I'm placing my rounds 1.2 inches high on my 100 yard zero and I'll hit high on my 200 yard 60 degree shot by about 2.4 inches.

    The quick answer is to try a 100 yard zero session at 60 degrees, but I don't have a cliff or tower handy so I'll wait for the Rocket Scientist fellas to help sort this out.