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Thread: AR-15 Zeros and Trajectories

  1. #221
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    Nice. I will have to get some of those targets. I am not sure exactly where my 14.5" carbine is "zeroed" with the ammo I use, but I do know that I can aim at the center of a 3x5 card (between the hairline and upper lip) and have all rounds hit the card from 0-200 yards. I also know, from shooting, not programs, that if I aim at eye level on a fully exposed "average" guy (like me) all rounds will hit under the hairline and above the belt line between 0-350 yards. This gives me a warm fuzzy.

    The main thing is knowing.

  2. #222
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    Quote Originally Posted by Molon View Post
    From my original post of this thread . . .Choose your zeroing scheme based on the pertinent facts; not nonsense about “shooting through a cone.” When shooting at human targets, in the grand scheme of things there isn’t going to be any practical difference between a point of impact that has a negative deviation from the point of aim, (e.g. the bullet strikes 1.5” below the point of aim) and a point of impact that has an equal positive deviation from the point of aim (e.g. the bullet strikes 1.5” above the point of aim.) In other words, the absolute value of the point of impact from the point of aim (how far the point of impact deviates from the point of aim, regardless of whether it is a positive or negative deviation) is what we need to be concerned about.

    As you can see in the graph above, from the muzzle (0 yards) to approximately 62 yards, the 50-yard-zero has a slight advantage over the 100-yard-zero. Between the distances of 62 yards and 165 yards, the 100-yard-zero has the advantage. From the distance of 165 yards out to the 250 yards shown in the graph, the 50-yard-zero has a distinct advantage over the 100-yard-zero. Choose your zeroing scheme based on the pertinent facts....
    I know this is an older thread but in my case my AR is a defensive weapon from a civilian POV. I tend to think of it as the Swiss do, "in case we are ever invaded" (one way or another), so to speak. Yeah I like to go punch holes in paper and take Rifle classes once in a while but it's not too hard to keep a log on elevation for longer ranges, windage, temperature and different ammo. That's what we're supposed to do, Right?

    Anyway, my choice has become a 1-4 scope, zeroed to fifty meters. It is easier to zero with the lack of stellar accuracy of most of my practice ammo since the overall grouping is smaller. IMO it's optimal for my use. Most important is the zero of my defensive ammo.

    As a side note last year I spent several trips to the range in very cold and sometimes blustery conditions. Slow fire through one mag and then sit in the car for ten minutes until I could feel my fingers, then do it all over again for about 200 rounds. I did this to condition myself for extreme conditions. Funny though, I seemed to be the only person taking advantage of the weather.

    Since my rifle was keeping zero I didn't bother to zero it for a 0-50 yard class I took in the spring. Surprise, with the warmer weather I had to re-zero well over an inch at fifty yards. The main point is there are a lot of factors that effect accuracy, my ammo was below zero during my winter forays and around seventy for the class. It was from reading this thread a couple years ago that convinced me that fifty meters was ideal for my purposes. YMMV. Thank you.

  3. #223
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    Thanks for the original post! I followed the directions you so clearly gave on my old Colt removeable carry handle (6/3) for RIBZ, sighted a tight group at 25 and watched the magic as I clicked for the 50 and 100 yard zeroes. So handy.

    Sent from my Pixel using Tapatalk

  4. #224
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    Some great info here. Thanks for the education.

  5. #225
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    deleted
    Last edited by RetroRevolver77; 12-18-18 at 19:16.

  6. #226
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    Worth noting during these discussions is the correct use of both the ghost and peep apertures. Without going into the neuropsychological and perceptual weeds. When using your ghost ring, large aperture, you focus on the target and the post will center. When using the peep, small aperture, focus on the front sight and the post will center. In both cases do not pay attention to trying to center the post your visual cortex will do it for you provided you focus the target or the post as noted.

    Sent from my SM-G920V using Tapatalk

  7. #227
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    Quote Originally Posted by 7n6 View Post
    300 meter zero at 100 yards for a carbine is what about 5" high at that distance? I ask because almost all the AR zeros are based on 25 meter, 50 meters etc. While I used to have access to ranges that allowed rifles on the pistol ranges- that isn't the case anymore.
    Approx 4” depending the bullet/load, but it will not have reached its apex yet and that happens around 175yd at 5”.


    Andrew - Lancaster, CA
    NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / NRA-ILA contributor, USCCA member

  8. #228
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    Those with carbine or shorter length barrels with the Non F marked front sight may want to consider the .06 post from Windham Weaponry. They have a kit with the extended .04 and .06 along with standard post and the adjustment tool. The .06 is the ticket if you want to do the RIBZ zeroed at 100 yards 6/3 -6 (-7 with buffer) and detachable carry handle. Must have if want to shoot the 62 gainers due to their higher point of impact.

    Sent from my SM-T520 using Tapatalk

  9. #229
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    This is a really great thread and the tutorial is awesome. I would bet a lot of money, at least $5 that the 25 meter zero was chosen because it is easier to do both in practice and logistically and faster. Plus teaching a private to shoot sucks!

  10. #230
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    I'm not sure how I missed this thread earlier, but I found it today. The opening post is an absolutely great explanation of nearly everything about "zeroing" an AR.

    One fact that appears several times in the original post is especially important to evaluating or discussing ANY zero:
    "this is only with a very few particular combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore"
    we too often forget that this is true of every zero in every gun.

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