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The other day I shot an AR15 carbine with a red dot optic mounted a few inches above the flat top receiver. The owner of this gun shoots almost exclusively at indoor ranges, so he's sighted it in at something like 10 yards to be dead on.

We shot it outdoors, and found it was quite a bit high of 25 yards but it was off the paper & even off the backstop 8 feet above the point of aim at 100 yards!!

I think a 50 / 200 yard zero makes much more sense because you never know when you have to might make a quick shot at 35, 50, 75, 100 or 150 yards, and you should not have to remember how many *feet* low to aim.
 

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184B84F5-5E9E-43D7-BB09-6C06E2988F7E.jpeg

This table from gundata.org shows the trajectory for an AR rifle with a 50 grain Federal 223 load when the optic's center sits 2.8 inches above the bore,

and The weapon is zeroed to be perfectly dead-on at 10 yards.
That bullet is sent upward at such a sharp angle to cross the line of sight so early in its flight ...

...that it reaches a maximum trajectory of several feet high around the 400 yard mark, and it doesn't even fall back close to the point of aim within 500 yards!
 

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I think a 50 / 200 yard zero makes much more sense because you never know when you have to might make a quick shot at 35, 50, 75, 100 or 150 yards, and you should not have to remember how many *feet* low to aim.
Absolutely. I've tried them all over the years but for most of what you'll need that one fits the bill.
 

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The other day I shot an AR15 carbine with a red dot optic mounted a few inches above the flat top receiver. The owner of this gun shoots almost exclusively at indoor ranges, so he's sighted it in at something like 10 yards to be dead on.

We shot it outdoors, and found it was quite a bit high of 25 yards but it was off the paper & even off the backstop 8 feet above the point of aim at 100 yards!!
I'll assume his indoor range is longer than just 10 yards. Perhaps 25 yards long? That's what my indoor range is. Did he never shoot at 25 yards indoor and notice he was "slightly" high? He didn't have to go outside to figure that out. So did he re-zero the gun to a more realistic range?

My ARs use the 50/200 Santose Improved Battlesight Zero. Works well for me out to 300 yards.
 

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At 25 yards you need to zero 1.5 to 2 inches low on the center depending on the ammo. 10 yards you need to be even lower than that but I've never zeroed a rifle at 10 yards. Or even then took one out to see where it hit at longer ranges.
 

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At 25 yards you need to zero 1.5 to 2 inches low on the center depending on the ammo.
You are right on the money.
That works great for folks wanting to get zeroed on but don't have 50 yards to do it. XM855 should be 1.6 at 25. You know well where it's gonna be at 50 and 250 is just tingling. After that the "couldn't hit an elephant" comes into play for a ways on out.
 

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I think his reasoning for sighting at 10 yards was that that was the most likely distance that he would face a situation where he would need to take an aimed shot in self-defense.

10 yds. is enough distance to the target that it would make sense to use sights or optics, rather than just pointing.

Any closer, say at 3 yards or 5 yards, I think anybody could point a rifle instinctively without even using sights.

But most self-defense shootings take place at less than 10 yards anyway, so why would somebody intentionally zero their weapon for 25 or 50 or 100?

I believe that's his line of thinking.
 

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But most self-defense shootings take place at less than 10 yards anyway, so why would somebody intentionally zero their weapon for 25 or 50 or 100?

I believe that's his line of thinking.
So that they might actually be able to reasonably hit their target at longer range if necessary?
 

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Now he's re-zeroed to be
1" high at 25 yards,
3" high at 100.
still 3" high at 200.
 

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It all depends on the caliber. I have AR’s in .22, 9mm, .233/5.56, 300 Blk and I’m currently working on one in 6.5 Grendel. It also depends on what you’re using the guns for.
 

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I zero at 50m typically. No more than about 2" high at 100, and then zero again at 200. Easy enough to do hold overs beyond that.
 

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Mine is zeroed at 36 yrd


 
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