Newb zeroing question

Discussion in 'AR-15 Discussion' started by jack80, Dec 28, 2012.

  1. jack80

    jack80 New Member

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    I'm trying to zero my Ruger SR556 and my back yard is sloped down about 15 degrees or so. That shouldn't have any effect at only 50 to 100 yards right?
     
  2. fsted2a

    fsted2a Active Member

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    First, are you zeroing iron sights or scope? If iron sights, you zero at about 25 yards, then set your windage knob forward. If you are zeroing a scope, start at 50 yards, then walk your way forward in 25 yard increments. Be a good idea to invest in a spotting scope to save walking back and forth every 3 round shot group, whether scope or iron sights are used. Learn to use the tics on the reticle as a bullet drop compensator to adjust for elevation and windage. The art of marksmanship involves making tweaks in your technique for environmental considerations not found in a sterile indoor range.
     

  3. jack80

    jack80 New Member

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    Thanks for the info. It's just my iron sights right now. I didn't know you were supposed to do it at 25 yards, I thought it was supposed to be 50. Shows how much I know haha
     
  4. racer_x

    racer_x New Member

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    Hornady ballistic chart

    223 55g vmax -1.5 muzzle, 1.4 100yrd, 0 200yrd, -7.0 300 yrd, -21.4 400 yrd, -45.9 500 yrd

    556 55g gmx 20" barrle -1.5 muzzle, 1.6 100yrd, 0 200yrd, -7.8 300yrd, -23.9 400yrd, -51.5 500yrd

    mayb that will help ya some I zerod mine at 75yrds
     
  5. ZeusEcho

    ZeusEcho Member Lifetime Supporter

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    I would sight irons and red dots (non magnified) at 50 yds. Most 223 and 556 will then also be close to zero at 200 yds.

    Magnified scope I would sight at 100 yds.

    I thought your original question though was more related to angle of the shot (15 degree decline) and how that would affect the bullet drop. It will have an affect but at 50-100yds its probably not significant.
     
  6. purehavoc

    purehavoc New Member

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    Maybe this will help, I like to use the 50/200 it keeps the drop alot closer together

    [​IMG]
     
    Last edited: Jan 3, 2013
  7. jack80

    jack80 New Member

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    Yeah that was the original question. I figured at such a short distance it wouldn't matter but just wanted to double check.
    Thanks for the info guys. As soon as I get home from the oil patch ill try it out
     
  8. fsted2a

    fsted2a Active Member

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    Army manual (TM 23-9) say do it at 25 meters, which equals about 30-35 yards. 50 yards should be good to go. If you do it that way, you will keep it on the paper. After that, it is more up to your marksmanship fundamentals (Breathe, Relax, Aim and Squeeze). Not knowing what your skill level was and basing your question off the title of the thread is how I based my esponse.
     
  9. 70cuda383

    70cuda383 New Member

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    Yea, at the end of the day, it's all on you and your personal preference. look at the ballistic chart above, and notice how your bullet flight path changes based on a 25, 50, 75 yard zero. as long as you know and understand what your bullet is doing in flight, it doesn't matter if you zero at 25, 50, or 75 or even 100.
     
  10. fsted2a

    fsted2a Active Member

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    Skill level has a lot to do with it too. If you are comfortable zero at 100 yards, go for it. If you have never picked up an AR before, 25 or even 15 is recommended. I personnaly know some guys who don't have a problem setting their weapon at mechanical zero and going to the range and qualifying expert without bothering to shoot a few rounds to zero.
     
  11. kbd512

    kbd512 Well-Known Member Lifetime Supporter

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    I see other posters have already given you lots of advice on ballistics data, but to answer the question as I read what you have posted, let's explain the difference between the bullet's drop and the line of sight to your target.

    If you were to draw an imaginary line from the sights of your rifle to whatever you're pointing at, you would have defined the line of sight. Bullet drop is the distance between your light of sight to whatever you aimed your rifle at and the actual flight path of the bullet, which is always a vertical measure and usually a negative number except for very close to the muzzle of the rifle.

    Your elevation above sea level and the ambient temperature (both affect air density) are going to have a lot more effect on the strike of the rounds on your target than a 15 degree depression at 100 yards.

    Between 0 and 100 yards or so for 5.56MM NATO ammunition, there's very little difference in bullet drop except at extreme firing angles.

    The question you posed is something to consider when shooting at extended distances and/or more extreme angles. Then there's lots of stuff to consider.

    Hopefully my explanation didn't serve to further confuse you.
     
  12. treehugger49

    treehugger49 New Member

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    25 meters = 27.34 yards, just for the record.
     
  13. fsted2a

    fsted2a Active Member

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    I'll buy that. I think the reason the military zero's at 25 meters is that there are a lot of folks coming through that never fired even one round of anything prior to joining, and 50 meters on a 8 1/2 x 11 paper is pushing it for some at first.
     
  14. 2tone0311

    2tone0311 New Member

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    The reason the military zeros at 25 meters is because ballistically speaking the rounds point of aim and point of impact ad the same same at both 25 meters and 300 m which is the "normal" range of fire fights in combat.
     
  15. fsted2a

    fsted2a Active Member

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    At least it was when the doctrine was written, which was during the cold war. From what recent engagements I have seen the AAR's on, the range is much closer in recent times. But the zero is still a good range for most troops.
     
  16. Solon

    Solon New Member

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    I'm still wet behind the ears with scopes and AR-15s, but if I read the chart right, the poa/poi is the same at the far end at 375y/343m. Of course it would be easier to follow the chart if Havoc would change his avatar. Please...just for the chart posts...:D
    Are the ballistics for .223Rem substantially the same as .556 military. I'm going to be scope zeroing myself this weekend.
     
  17. 70cuda383

    70cuda383 New Member

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    There was a ballistics chart posted? Where? I didn't see anything:confused: