SIGHTING A SCOPE IN

The #1 community for Gun Owners in Indiana

Member Benefits:

  • Fewer Ads!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • diver dan

    Sharpshooter
    Rating - 100%
    8   0   0
    Jan 21, 2013
    668
    43
    DeMotte
    I am not sure about this.If you sight in a gun at 25 yards, is it sighted in at 100 yards.I vaguelly remember something like this, but not sure.
     

    Mark 1911

    Grandmaster
    Rating - 100%
    12   0   0
    Jun 6, 2012
    10,931
    83
    Schererville, IN
    All depends upon the trajectory of the ammo you are using.

    Most ammo manufacturers publish trajectory curves for each product they sell. So if you are shooting Federal 30-06, blue box, 150 grain, power point boat tail for example, you should be able to find the product / catalog number on the box, go to their website and find the trajectory curves for that particular product.

    Sometimes they will even give more than one set of curves, sometimes a curve for 100 yard zero and another for a longer or shorter distance zero. Depending on the ammo, maybe they give a curve for 50 yards and another distance. Regardless, if you can find the curve, you will know the answer to your question. Sometimes they give the data in the form of a table instead of a curve, basically the same data. Sometimes they even print the table right on the box.

    From those curves, you can see where the curve crosses the zero mark. For a 100 yard zero, there will be another point closer in where it crosses the zero.

    Keep in mind the curves are estimates that can vary for your gun, barrel length, etc. But should get you pretty close.

    If you can tell me what ammo you're shooting, with the catalog number on the box, I can see what I can find for you.
     
    Last edited:

    LarryC

    Master
    Rating - 100%
    1   0   0
    Jun 18, 2012
    2,418
    63
    Frankfort
    I am not sure about this.If you sight in a gun at 25 yards, is it sighted in at 100 yards.I vaguelly remember something like this, but not sure.

    This is true ONLY with certain Ammo and sights / scope. For instance the standard M16A2, when zeroed at 25 meter is also zeroed at 300 meter.

    The ammo trajectory is one factor and the height of the sights / scope is the second. Using the same ammo, the distance from the center-line of the bore and the center-line of the sights determine the angle you are holding the rifle at when you sight in at 25 yard. The higher the angle (caused by the higher mounting of the sights / scope) will cause the bullet to reach a higher altitude before dropping - therefore increasing the distance that the bullet will travel before hitting a target at the same zero.

    IE: A very high mount may cause a bullet zeroed at 25 yards to travel 300 Yards before crossing the Zero line again on its way down.

    Obviously the flatter the bullet trajectory will also cause the same situation. IE: A flatter trajectory will cause the bullet to remain above the target for a longer distance. This trajectory (estimate) may be listed by the cartridge manufacture, but is also dependent on your firearm (barrel length, semi auto vs bolt action, bore diameter and condition, suppressor, gas porting etc.).

    It is obvious that this can all be calculated using trigonometry, but is far simpler and more accurate to just shoot the firearm with the ammo you use at various distances to determine what distances you will use to Zero your gun!
     
    Last edited:

    mlouisalbert

    Plinker
    Rating - 0%
    0   0   0
    Sep 15, 2012
    55
    8
    Elkhart
    I am not sure about this.If you sight in a gun at 25 yards, is it sighted in at 100 yards.I vaguelly remember something like this, but not sure.

    No it will not be. Now if you "zero" a rifle at 25 yards you should be able to hit the target at 100yards giving you the chance to zero there but they will not be the same zero.

    I use a bore sight like this one to help in the process but there are other ways to do it if you are wanting to burn up some more ammo...

    https://www.cabelas.com/product/sho...ser-chamber-boresighters/1195812.uts?slotId=0
     
    Top Bottom