Elevation levels for sighting in a rifle

Discussion in 'Long Range Hunting & Shooting' started by hatfield954, Feb 16, 2011.

  1. hatfield954

    hatfield954 Well-Known Member

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    I hope this is the right place for this question. My brother in law and my father in law, both tell me this. When sighting in a rifle, does it matter if the elevation plane between the rifle and target are on a level plane? They have told me, that the target can be at a much higher or lower angle than the rifle and it will still sight in correctly. Meaning that I would not have to compensate for the difference, that I could still sight a rifle in straight. Like the angle difference means nothing and should still sight in straight. I don't believe that for one second. I believe you should sight in and shoot on as level of a plane as possible even though real time shots during hunting would be different. Who can tell me the truth on this one?
     
  2. robbobsam

    robbobsam Well-Known Member

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    I am probably not the most experienced guy to give this advice but I believe you should zero a rifle on a flat plane. If you zero it on a 45 degree angle and you load your zero on exbal as 100yds the figures generated would all be out as technically you wouldnt be 100yds away ballistically. I think you would have about a 50-60 yds zero.

    If I am wrong here guys please set me straight.

    If you dont intend to shoot at long range but would be happy with point and shoot at deer sized targets up to 200yds I am sure it would make very little difference.
     

  3. kcebcj

    kcebcj Well-Known Member

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    The closer to level the better but.......at a hundred yards a slight angle up or down will be almost undetectable for most and should not concern you. With that said angle does play an important role when shooting at distance. There is a lot of threads on this forum that can get you up to speed.
     
  4. Long Trang

    Long Trang Active Member

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    The interesting word you used was 'much'. Your brother and father in law told you "that the target can be at a much higher or lower angle than the rifle and it will still sight in correctly". As robbobsam and kcebcj said, a slight angle and short range distance shouldn't make much of a difference. However, a 'much higher or lower angle' and the farther the distance will certainly through off the shot.

    Essentially, if you zero your rifle at a steep angle and at 500+ yards, as long as you shoot near that same angle, your shots will be on. Once you use that zero for a flat trajectory at similar distance, your shots will be low.

    Your best option is to zero at a relatively level trajectory (up to 10 degrees up or down doesn't affect the trajectory) and then aim low if you need to take an angled shot. Once again, a short range and a slight angle will not throw off your shot enough to notice.

    Good luck
     
  5. hatfield954

    hatfield954 Well-Known Member

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    Thanks men, for your responses. I felt like I was more right than they were. As for the angle I have talked about, it was roughly 40 degrees at 100 yards, shooting at an uphill target.
     
  6. NWmissouriman

    NWmissouriman Well-Known Member

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    I'm reviving this thread because I came across it when looking for an answer to a question I have.

    Generally, I sight my rifles in from a bench with my target being roughly 4' high (or nearly level with my bench for the most part). I've got a new load for my long range rig and decided I might try something different. Due to the fact that I'll be shooting it off from a Harris bipod and from the prone position, I thought that I might zero it at 100 yards off of the bipod and from prone. My question is this, should I still leave my target height the same (4'ish) or should I move my target for zeroing prone down to say 1' (roughly the height of my scope from the ground)? Hopefully this makes sense and someone can give me some solid advice on which would be better.

    Thank you!

    Edit: I guess my question was kind of answered in the above posts, but what I really want to know is how much difference one will make over the other out to 1,000 yards? What would you guys do when zeroing?
     
    Last edited: Aug 7, 2014
  7. FearNoWind

    FearNoWind Well-Known Member

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    I agree that a slight difference in elevation over 100 - 200 yards shouldn't have a dramatic effect. But it's still relative. The greater the difference in elevation the greater the error factor. Rule of thumb, as I learned it, was as long as the degree of slope is less thatn 10% no correction should be necessary. So if your 100 yard target isn't more than 30 feet above or below below your shooting position you're good to go.
     
  8. NWmissouriman

    NWmissouriman Well-Known Member

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    That makes sense, but I'll ask anyways and you can correct me if I'm wrong. Barrel is 1' off the ground, Target is 4' off the ground, distance is 300': So 4'-1'=3', 3'/300'=.01, so my slope is 1% and no correction would be needed and it would be ok to sight in this way? Am I calculating this wrong? Or should I just move the dang target down to 1' or so off the ground, sight in and go on:D?
     
  9. FearNoWind

    FearNoWind Well-Known Member

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    Your target is 300 feet away and the difference between center bore and center of target is 3 feet. 3 feet is one percent of 300 feet. Go for it ........ you're waaaay inside the margin.
     
  10. NWmissouriman

    NWmissouriman Well-Known Member

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    :cool: Thanks for the input. I've been running this through my head for a few days now. It's easier to make a decision when someone else tells you that it's the right thing to do, haha.
     
  11. FearNoWind

    FearNoWind Well-Known Member

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    When walking on ice in unfamiliar territory it's usually a good idea to ask the locals if there's a lake under it. I'm kinda like you. I hate surprises. :D
     
  12. BrentM

    BrentM Well-Known Member

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    I have a cosine angle chart on my rifle that allows me to deduct x yards per 100 yards depending on slope percentage. In the event of a electronic gadget failure.

    5 = -1
    10 = -2
    15 = -4
    20 = -6
    25 = -9
    30 = -13
    35 = -18

    If you zero'd at 300 yards with a 10 degree slope you would subract 6 yards, your real zero would be 294 yards.

    As said before the slope at short distances generally is not that that big of a deal, so lets you say you zeroed at 100 yards with a 35 slope. You are zeroing at 82 yards. If you shot 1000 yards with 82 zero but used 100 as your zero the difference is .1 MOA. However, if you do that at 200 yards, your actual sight in distance is 164. The MOA change at 1000 is .5 moa.
     
  13. NWmissouriman

    NWmissouriman Well-Known Member

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    Very useful information! Thank you. I plan to zero @100 and set my zero stops. I use to zero around 250+/- depending on how high my bullet got in flight, but I think I'm going to change my approach. Zero @ 100, set my stop, and possibly just turn it up 1-2 moa before going out hunting. I really just wanted to make sure I wasn't shooting myself in the foot for long range purposes by sighting my rifle in off from a bipod and prone this go around while shooting at a slight uphill angle. I appreciate the replies!
     
  14. 4xforfun

    4xforfun Well-Known Member

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    You better re-think the first part of theis statement. If you zero at..say 500 yards and 45 degree angle, you will always be dead on at 500 yards and 45 degree angle. True enough.

    But, If you are dead on at 500 yards and 45 degrees and you have a shot at 1000 yards..at whatever angle, how are you going to deturman your holdover/dial ups? What is your process?

    Just askin,
    Tod