Sighting in question -- Need help with distance Calculation

Discussion in 'Rifle Talk' started by mmessuri, Jul 13, 2005.

  1. mmessuri

    mmessuri Guest

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    I only have a limited amout of space (60 yds) for sighting in my rifle (this is on my own property) and I would like to have it set for a 200 yd zero. My question is at 60yds how high should I be on the bullseye? (some books that I have read mention that you should sight in your rifle at 3 inches high at 100 yds {this breaks down to .03 inches per 10 yds} ).

    The weapon that I am using is a Remingtion Model 7400 .270 (with a 3x9 scope) and the ammo is the 130 GR Power Point Winchester 270 ammo.

    I would also be interested in what the forumla is for the actual "how high" calculation is.

    Thanks.

    -- Michael --
     
  2. Papadoodles

    Papadoodles Super Member

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    re: Sighting in question -- Need help with distance Calculat

    If you put your 130 bullets exactly dead-on at 25 yards you will be good from the muzzle to about 220 yards without being more than 2.5 inches above line of sight.

    I'm sure someone here can point you to a trajectory software on-line where you can put in your figures and get exact measurements.
     

  3. wired

    wired Guest

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    re: Sighting in question -- Need help with distance Calculat

    Just posted something like this a few days ago. Should still be on here. Either way, about the best way to find out is to look at the ballistics chart for the ammo you're using. Go to the ammo manufacturer, and they'll have that information. Typically, it'll show info in 50-yard increments.

    PapaD is right on. With most flat-shooting calibers, if it's sighted in dead on at 25, it'll at least be on paper at approximately 200 (depends on the bullet, which is what the ballistics charts are for). The best way to do this is to use the 25-yard rule to get it close, and then find someplace you can shoot 200 rounds to do the final adjustments. You'll want to periodically check your zero at 200, as well, just to make sure. I was posting about it because the local indoor range is only 20 yards, not that the 5 yards that close is going to make a noticeable difference (especially since I'm going to be checking it out at 200 anyway).

    By the way, the actual "formula" would be either non-existant or very large if it were to be halfway accurate. There are a lot of factors. Barrel length, action type, rate of twist, type/weight of bullet, type/weight of powder, friction caliber.... and then it actually leaves the barrel. Then, you get to factor in humidity, atmospheric pressure, wind, temperature, wind resistance, etc. That's why there are so many ballistics charts, and even then, they can only give us approximate values. Ask a serious shooter in long-range (in the nature of 1000 yards) target and varmint work. They'd probably give you the best info.
     
  4. mmessuri

    mmessuri Guest

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    re: Sighting in question -- Need help with distance Calculat

    Thanks for all of the helpful info. After reading it all, I will be using the "dead on at 25 yds" method. As a side note I started to play with this program called Shoot! from http://www.ballistics-software.com/ that seems very informative on these matters (and simple to use).

    I am off to go shoot some paper so have a great week.

    -- Michael --
     
  5. Papadoodles

    Papadoodles Super Member

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    re: Sighting in question -- Need help with distance Calculat

    Good Luck!!
     
  6. wired

    wired Guest

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    re: Sighting in question -- Need help with distance Calculat

    I will recommend once more that you'll want to take it somewhere you can shoot 200 or so yards before you actually use it to hunt, just to verify.

    Good luck, and have fun shooting!!
     
  7. mmessuri

    mmessuri Guest

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    re: Sighting in question -- Need help with distance Calculat

    wired:

    >>I will recommend once more that you'll want to take it somewhere you can shoot 200

    I do have this in my plans for the future (before hunting season) just not right now.

    Thanks for all of your help.

    -- Michael --
     
  8. wired

    wired Guest

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    re: Sighting in question -- Need help with distance Calculat

    I figured you would go out and do it. I know a lot of guys that would call it good after getting it on paper at 25 yards, so I was playing it safe.