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AR15 iron sights mechanical zero Login/Join 
Now and Zen
Picture of clubleaf206
posted
When installing iron sights on a AR15 is this something that is important to do? Or is it enough to install the sight(s) and then boresight it/them before going to the range?


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"....imitate the action of the Tiger."
 
Posts: 12159 | Location: The untamed wilds of Kansas | Registered: August 25, 2001Reply With QuoteReport This Post
Yeah, that M14 video guy...
Picture of benny6
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Well, there's no real front sight windage zero adjustment like there is with the M14 and M1 Garand. The most important thing to do is dial in your windage and elevation at the range for a "BZO" or Battlesight Zero.

You can adjust your front sight height so that the elevation drum at the rear sight is calibrated for the indicated distance.

I do this to all my rifles. I actually have set screws on my AR15 front sight that allow me to adjust the cant of the front sight to that my windage is zeroed when my rear sight is set to zero.


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Posts: 5335 | Location: Auburndale, FL | Registered: February 13, 2001Reply With QuoteReport This Post
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Picture of sourdough44
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I may do a ‘poor man’s bore sight’, looking through the bore. Of course that’s gonna barely get you in the ballpark.

More importantly is to start with a larger target/cardboard at a closer range, 25-40 yards.

With those first shots, I’ll often use oddball ammo & adjust with single shots. As you tune, better ammo, longer ranges, a few shots to adjust.
 
Posts: 6098 | Location: WI | Registered: February 29, 2012Reply With QuoteReport This Post
Frangas non Flectes
Picture of P220 Smudge
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I don’t even bother with that and just zero when I get to the range, same basic routine as sourdough. With red dots and scopes, I try to bore sight first, but with irons, any extra fiddling before I can see where shots are landing feels like wasted time.


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Posts: 16988 | Location: Sonoran Desert | Registered: February 10, 2011Reply With QuoteReport This Post
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Picture of 4sigman
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No real reason to do this unless they look wildly off center when you install them. The myth that was perpetuated in the military forever was that if you recorded your zero adjustments from mechanical zero, that you could then apply those adjustments to any rifle and have it be zeroed for you. This just isn't true.
 
Posts: 272 | Location: Southern NH | Registered: April 01, 2006Reply With QuoteReport This Post
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IME, a crude boresighting has more potential to be beneficial on the first range outing, than a mechanical zeroing.

If the front sight is attached to the barrel, the barrel's alignment relative to the receiver, and how close to perfectly vertical the front sight is will come into play.

If the front sight is mounted to the handguard, the handguard's relationship to the barrel and upper receiver can be imperfect in a few different ways.
 
Posts: 1981 | Location: Northeast GA | Registered: February 15, 2021Reply With QuoteReport This Post
Now and Zen
Picture of clubleaf206
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It sounds to me, then, that this would be something of little or no benefit.

Another question. What does everyone think of the 50/200 yard zero?


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"....imitate the action of the Tiger."
 
Posts: 12159 | Location: The untamed wilds of Kansas | Registered: August 25, 2001Reply With QuoteReport This Post
Sigforum K9 handler
Picture of jljones
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quote:
Originally posted by clubleaf206:
What does everyone think of the 50/200 yard zero?


Picking a zero is a math game. You hear people debate 50/200, 100/300, 36/???? And so on constantly. I’m not hot nor cold about it. Look at the ballistics and figure how it best serves you. 50/200 allows the same chest point of aim effectively out to an average of 225 or so. Once you pick one, know and understand your holds. Very easy.

People seem to endlessly debate the virtues of various zeros and truthfully it doesn’t matter if you commit to knowing your zero and holds based on your rifle. The 50/200 is probably the most used by LE.




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Posts: 37008 | Location: Logical | Registered: September 12, 2004Reply With QuoteReport This Post
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Picture of 1KPerDay
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quote:
Originally posted by clubleaf206:
Another question. What does everyone think of the 50/200 yard zero?

I'm not really a rifleman; I mostly do 3-gun stuff and lumber around. But for me, at the distances I shoot, the 36-yard zero makes the most sense on my ARs with a dot.

https://youtu.be/jttB1kUXfJE?si=_I78R_Ggwo4UvO5a


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Posts: 3147 | Registered: February 27, 2013Reply With QuoteReport This Post
Prepared for the Worst, Providing the Best
Picture of 92fstech
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I don't bother with bore-sighting anymore. The boresighters I've used in the past were cheap and imprecise, and I ended up just walking it in anyway.

I like the 50 yard zero for my ARs, because it keeps things simple for my expected engagement range (plus my gun club rifle bay only goes out to 200) so I typically start there and 95% of the time it's already on paper. If it's not I'll move up to 25 to get it on paper, then go back to 50 to fine-tune. Like sourdough44 said, a nice big clean cardboard backer can help, too.

.223/5.56 ammo is cheap. Trial and error isn't a hardship. I might use a different approach (and a farther zero) with a scoped magnum hunting rifle.
 
Posts: 8187 | Location: In the Cornfields | Registered: May 25, 2006Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
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I had a trainee zero a new AR’s mechanical (“iron”) sights a few days ago and we used the procedure I’ve used for many years: A very easy to see target with precise aiming point on a large white backer with firing from a firm bench rest. Because the rifle was going to be zeroed at 50 yards, that’s where I placed the target, but I was prepared to move it closer if the first shots weren’t on paper.

The first shot was several inches high and a bit left. After a little dialing based on crude estimates (e.g., “Try six clicks down”) the bulk 223 stuff was hitting close to point of aim, and I switched to carry grade ammunition for final zeroing. The total time was maybe 15 minutes (okay, probably a bit more, but not much). No bore sighting or fiddling with the sights first.

In addition to using a large backer to easily spot hits, a good zeroing target suitable for the type of sight(s) makes things easiest. For irons, I like the large blue “V” of the Mountain Plains series:



(The above target is just an example, not the one in the recent zeroing session.)

In use, the sight picture looks like this. Although I prefer the Mountain Plains target for a couple of reasons, any contrasting color and a bottom point such as turning a piece of construction paper so one corner is down works as well.



I’ve ordered MP targets directly from the company because they seem to be hard to find otherwise:

https://www.precisionplustarge...vr_target_desc_8.htm

And I am another fan of a 50 yard zero. I have no intention of engaging fleeting targets in the mountains of Afghanistan, so that’s fine for my purposes.




6.4/93.6

“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
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Posts: 47275 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
semi-reformed sailor
Picture of MikeinNC
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quote:
Originally posted by clubleaf206:
It sounds to me, then, that this would be something of little or no benefit.

Another question. What does everyone think of the 50/200 yard zero?


If you are going to use iron sights, then you should zero the rifle like the sights are designed for. If they are USGI sights, you can use a 25M zero that will match the sights and the ballistics of the bullet it(the sights) were designed to. Or you can use a 300m zero. Which is what the M16 series was designed for.

If you are going to use a different bullet weight,(not 62grain or 55) then you can set them at whatever and realize the impact won’t line up with the hash marks on the elevation drum.



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Posts: 11182 | Location: Temple, Texas! | Registered: October 07, 2006Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
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There are countless types of “iron” sights made for AR-15 type rifles these days that don’t have markings to permit quick elevation shifts for different distances. That’s true of all such sights I’m familiar with, and I’d bet a nickel that it’s true of the vast majority of other commercial models as well.

What’s more, none of the rear sights I own even permit changing the elevation: That’s all—and only—done with the front sight. The GI type rear sight that’s intended for use with a specific zeroing range with a specific type of ammunition might be useful for anyone who anticipates engaging hostiles with the irons at 800 meters, but it’s unlikely to be of value for the rest of us.

I suspect that virtually all commercial sights are designed to allow the user to zero them at any distance they wish.

As they should be.




6.4/93.6

“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 47275 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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quote:
Originally posted by clubleaf206:
It sounds to me, then, that this would be something of little or no benefit.

Another question. What does everyone think of the 50/200 yard zero?


For red dots and optics where nothing obstructs the ability to hold over, I use a 50/200. But I would stress that it is important to fine tune that zero at an actual distance of 200 yards.

I have seen MANY people over the years turn up at their first competition with a red dot zeroed at 50, assuming that they were good to go. They promptly bombed on any targets beyond 100 yards, because there was enough error in their 50 yard zero that they were unable to discern and didn't bother to confirm on long range targets.


When I used to shoot limited division and before they allowed red dot sights, I used a 300 yard zero with iron sights. This requires you to hold under slightly on smaller targets at 100 yards, but it gives you longer minimum point blank range on silhouette size targets, out to 350 yards.

Holding over with irons is particularly difficult because you are obscuring the target with the front sight post. Dialing with an A2 style rear sight is too slow on a multi-target array of varying distances.

50/200 could work fine with iron sights if your maximum distance of engagement is going to be 250 yards or less.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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quote:
Originally posted by 92fstech:
I don't bother with bore-sighting anymore. The boresighters I've used in the past were cheap and imprecise, and I ended up just walking it in anyway.



I always considered bore sighting to be an exercise in futility. Best case scenario, it gets you on paper at 100 yards. Maybe.

Shooting one round at 50 yards on a large piece of cardboard accomplishes the exact same thing.

Some people bore sight and take that rifle hunting without ever firing an actual round to zero properly. Which is absolute lunacy.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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quote:
Originally posted by clubleaf206:
When installing iron sights on a AR15 is this something that is important to do? Or is it enough to install the sight(s) and then boresight it/them before going to the range?



Both would be a waste of time. Start at 25 yards. Zero the rifle. This should get you on paper at 300 yards. If you want to use a 300 yard zero, fine tune that zero at 300 yards.

If you want to use a 50/200 zero, after 25 yards, move to 50. Fine tune at 50. Then move to 200, and fine tune your zero again.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Now and Zen
Picture of clubleaf206
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Maybe I'm misunderstanding the concept of a 50/200 yard zero. A 50/200 yard zero allows you to have point-of-aim and point-of-impact at both 50 yards and 200 yards, correct? Then you aim about 1.5" low at 25 yards and 1.5' high at 100. And honestly, for the purpose I envision the rifle for I don't know that I need to go farther than 200 yards.


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"....imitate the action of the Tiger."
 
Posts: 12159 | Location: The untamed wilds of Kansas | Registered: August 25, 2001Reply With QuoteReport This Post
Music's over turn
out the lights
Picture of David W
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quote:
Originally posted by clubleaf206:
Maybe I'm misunderstanding the concept of a 50/200 yard zero. A 50/200 yard zero allows you to have point-of-aim and point-of-impact at both 50 yards and 200 yards, correct?


Yes



David W.

Rather fail with honor than succeed by fraud. -Sophocles
 
Posts: 3630 | Location: Winston Salem, N.C. | Registered: May 30, 2005Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
posted Hide Post
quote:
Originally posted by clubleaf206:
Maybe I'm misunderstanding the concept of a 50/200 yard zero. A 50/200 yard zero allows you to have point-of-aim and point-of-impact at both 50 yards and 200 yards, correct? Then you aim about 1.5" low at 25 yards and 1.5' high at 100. And honestly, for the purpose I envision the rifle for I don't know that I need to go farther than 200 yards.



That is it exactly. The reason that I emphasize the need to fine tune the zero at 200 is because within the natural dispersion of a group at 50, there is likely some error in the actual zero that is indiscernible from the natural dispersion of a rifle that doesn't shoot .1 MOA.


When you confirm your zero at longer distances, it helps to mitigate an unrealized error.

Invariably, when I step out to longer distances with a new rifle or a new load, I will wind up tweaking either windage, elevation, or both, from what my starting point was at 50 yards.

Don't trust a 50 yard zero to be exact at 200 yards. It's a recipe for failure if targets are small enough to expose slight errors in your zeroing process.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
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Your POA would be high at 25; low at 100. Per the image from David W.
 
Posts: 1981 | Location: Northeast GA | Registered: February 15, 2021Reply With QuoteReport This Post
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