Sighting for 100 yards when I only have 25

Discussion in 'Optics & Mounts' started by rfalls1891, Feb 17, 2014.

  1. rfalls1891

    rfalls1891 New Member

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    Just finished my first 300 Blackout build and mounted a Vortex Crossfire 2x7 on it. I was hoping someone could help me with a question I need answered before this weekend. If I only have the opportunity to sight my AR at 25 yards, how high above the POI do I have to sight the crosshairs on a paper target for it to be within less than inch between POA and POI at 100 yards? Any info anyone can provide would be greatly appreciated. :)
     

  2. c3shooter

    c3shooter Administrator Staff Member

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    Well, since you did not give us a HINT about what BULLET you are shooting, would suggest you start about 1 inch BELOW the aim point. The bullet is still rising to the line of sight on most AR type firearms. And I have seen 300 Blackout run from 120 to 240 gr bullets at different speeds.
     
  3. nitestalker

    nitestalker New Member

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  4. John_Deer

    John_Deer New Member

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    Depending on the height of your scope rings the gun is going to shoot at least a couple inches high at 100 yards if you sight in at 25 yards.

    You are not wasting your time sighting in at 25 yards. If you have the rifle sighted in at 25 yards it will only require a few shots to get the rifle dead on at 100 yards.
     
  5. c3shooter

    c3shooter Administrator Staff Member

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    Nitestalker- bullets begin to drop the instant they leave the barrel- IF the bore is level.

    However, as that article explains- almost every rifle will be tipped up to some degree. The bullets travel in an arc (a parabola) that passes upward thru the line of sight, and drops BACK to the line of sight at the target.

    Except for my phased plasma rifle in the 40 watt range. It shoots flat. :p
     
  6. nitestalker

    nitestalker New Member

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    That whole gravity thing is confusing .:D
     
  7. yazul42

    yazul42 Active Member Lifetime Supporter

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    c3,,, is that plasma rifle legal for elk and what would be the minimum wattage you would recommend?
     
  8. rfalls1891

    rfalls1891 New Member

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    Last edited: Feb 18, 2014
  9. nitestalker

    nitestalker New Member

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    Yes it is much better than the "I think and try this".:)
     
  10. seancslaughter

    seancslaughter New Member

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    No problem I was in the same situation with my 6.8 and that target got me to within a small adjustment to bullseye at 100


    Sent from my iPhone using Firearms Talk
     
  11. c3shooter

    c3shooter Administrator Staff Member

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    The whole theory of gravity thing came to me one morning as I stepped on a patch of ice at the top of the steps.

    The Phased plasma rifle is legal for elk, but not until 2038. If you carry one now, you need a TJL. (Temporal Journey License) 40 watt does well for Moose. Elk get 30, Mulies 20, Antelope 10. Use the wrong wattage, they will be tough and stringy, or crunchy.
     
  12. c3shooter

    c3shooter Administrator Staff Member

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    Rfalls- glad you got what you needed. We sometimes get a touch goofy here.
     
  13. Pasquanel

    Pasquanel Proud to be an American Supporter

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    In my 30-06, 150 gr. loaded on the hot side I sight poa at 25 yards (dead on) this puts me about dead on at 200/220 yards and about 1 1/2" high at 100.
    Just about perfect for my style of hunting in this part of the country. Some tweaking is/will be required.
     
  14. yazul42

    yazul42 Active Member Lifetime Supporter

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    At what government agency does one apply for a TJL?