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Rifle Scopes What Zero distance is best?

TimActual

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Full Member
Minuteman
Jul 21, 2013
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Riverside, CA
Howdy, I thought that some of you may have different perspectives on what distance is best to zero on that you may feel like sharing.

I will be shooting a Savage model 10 BA rifle with a Nightforce 8x32 56 scope.

That said, what factors does one consider to determine the distance for their zero?

Do you pick a specific distance for your zero and stick with it, or do some people change their zero distance from time to time based on some criteria? I wouldn't think so but perhaps I'm wrong about that.

Here's probably a ridiculous question, but what if your intention is say to shoot between 100 - 1,000 yards. Why not set your zero to somewhere in the middle like 500 yards?


Thank you kindly for your help,
T.
 
All mine are 100 yards. That way I am dialing up whether I am shooting in closer than 100 or farther out. Always dialing one way so much less possibility of getting lost on the dial. Also with a zero stop there will be no way to get lost.

A dedicated ELR rig would be the only place I would even consider a farther zero as it would be going out from that distance.
 
I don't get it: My rifle is zeroed at all distances.

OP, you bring up a very good point: If you are walking around, shooting between 100 and 1000, then dial your 500 zero.
 
That would be his 500 yard dope dialed on from where he is zeroed, as in knob is on zero. Dialing on dope or data from your zero point is not zeroing. It's just that, dialing on your dope/data. Graham stop trying to confuse him ;)
 
That would be his 500 yard dope dialed on from where he is zeroed, as in knob is on zero. Dialing on dope or data from your zero point is not zeroing. It's just that, dialing on your dope/data. Graham stop trying to confuse him ;)
LOL! First comes the confusion, then the realization.... That my 100 yard zero is simply dialing-off DOPE or data from my 500 yard zero point.
 
I'm with Rob01 100yds for me, but most of mine cross over as hunting rifles and I run a NPR1 reticle in a nightforce F1 so it makes for quick hold overs or I can dial if need be
 
I like 100yd zero with slow cartridges (308, 30-06, etc.) and 200 yd zero for anything faster.
 
I like 100yd zero with slow cartridges (308, 30-06, etc.) and 200 yd zero for anything faster.
No offense intended, but I like puppies, and kittens, and cookie-dough ice cream.

At what distance do you guys zero? That's a question more suited to an arf.com poll.

The OP's question: What is the BEST zero? Well, that answer is determined by the purpose of the zero.

So far absent from this discussion, and what I was trying to get at, is a discussion of a zero FOR WHAT PURPOSE.

If I am shooting a light rifle at 100 yards I zero at 100 yards.
If I am shooting comps with my very adjustable gear I zero at 100 yards, because I can.
If I am zeroing a .50 with a SB scope and Christmas-tree reticle, then I zero at 500 yards.
If I am flash-milling I zero based on the size of the target and the likely bracket distances.
If I can't dial, and need to snap-shoot 72" targets out to 840m with a .308, then I would consider a reverse-image zero.

My point was that the important thing is not the distance at which the rifle is 'zeroed', but the understanding of the concept relative to the intended use of the equipment.
 
The OP asked for perspectives so I'll throw mine in for what it's worth. I ran a 300 yd zero on a .308 used for practical rifle type competitions for a couple years. I liked it cause it made dialing elevation pretty quick, only a few mils and less than a rev (5 mil knob on MK4) for most ranges I encountered. But I have switched to a 100 yd zero for the following reasons; First, I made mistakes on up vs down. In the stress of the moment I could remember the numbers or do the math, but would make mistakes occasionally with direction. Those were frustrating mistakes I can tell you. Missing by 3 mils because you added 1.5 instead of subtracting is... frustrating. Second, I found that zeroing my rifle for the conditions of the day was both more difficult and more critical. With a good 100 yd zero, I've found that I can adjust my drop table for the days atmosphere with greater certainty and often without firing a shot. I don't have a smartphone and carry paper drop charts for different DAs. Also, I have zero stops now, and holding low on targets inside of 300 isn't cool for me. Just my .02

So, what do you intend to use the rifle for? Cartridge? Zero stops on the NXS?
 
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I agree with Rob, except (1) when your scope setup has limitations, such as not enough up elevation to get to long range with a 100-yard zero and/or the wrong base on your rifle, and (2) rimfire. With 22LR the bullet drops are much larger than with centerfire cartridges, and shooting closer than your 100-yard zero can require hold unders (like when the wabbit shows up 25 yards away). For 22LR I prefer a 50-yard zero, but a 100-yard zero for 17HMR. It's better to dial up or hold over than to hold under because it requires more thought and potentially more mistakes.
 
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Wow, here I checked in hoping to see a reply. Be careful what you ask for I guess. Thanks guys.

My scope is the Benchrest model with an NP-R2 reticle. 2moa elevation/5moa windage. 1/8 moa clicks for both. Caps. I wish it had zero stops but it doesn't.

I may change my mind later, but I plan on dialing for elevation and holding off for wind. The rifle I grew up with uses .223 and has a 4x scope where I just held off for everything.

My new rifle is in .308 cartridge. To start and perhaps forever I'll be using Fed gold match 168gr BTHP. I have been advised to select a cartridge and stick with it.

I see mentioned multiple times that with a 100 yard zero you only have to adjust in one direction, so it's easier to keep track and not get lost. I think that's sound advise. The main purpose of the rifle is for ELR shooting, but I would also like to "walk" out to that, if that makes any sense.

I'm new to this (obviously), so I may discover what I think I want is not where I'll end up. Friendly matches sound pretty fun. My "MO" with my old rifle was to visit the desert and see how far out I could hit rocks. That was my thing and I loved doing that, the farther out I hit the happier I got, but I now want to reach out further than my .223 would get me. For my budget the .308 seemed a good compromise.

Right now I'm trying to learn as much as I can. I realize that when learning something new and complex the most important thing you can do is to learn the fundamentals in order to give yourself a good foundation to build on.

My friends give me a hard time because I haven't even shot my new rifle yet. But I would rather know what I'm doing first, rather than just wasting a bunch of ammo.

I now need to go look up flash-milling and reverse-image zero. Thanks Graham as I'm now ready to quit the whole darn thing! :)
 
I don't get it: My rifle is zeroed at all distances.

^^^This

I believe there is a best zero and its 100 yards, unless you're talking about a dot sight or other difficult to zero optic. The rifle & optic are plain stupid and do not know what number is displayed on the turret.

If you zero at 100 yards, then dial in your 25, 50, 200, or WHATEVER dope (regardless of caliber)...your rifle is now "zeroed" at that distance and you can use the appropriate holds for shots away from that distance. The reticle is pretty stupid too...it could care less what's displayed on the turret. For example when its dialed for say 300 and you want to hold for a 500 yd shot. A 100 yard zero allows you to change your zero with a simple turn of the dial. (providing your optic allows such quick/easy elevation changes) Its almost a no-brainer
 
All my magnified optics are zeroed at 100 yards. All my red dots are zeroed at 50 yards.
 
Why do people consider dialing on dope zeroing? It's not. You can dial on a certain dope and then use holds from there but it's not zeroing at the range you dialed on. Your elevation knob is not on 0. Your zero is when your elevation knob is on 0 and you have POA/POI at whatever distance you have it set for. As I said my rifles are zeroed at 100 yards. My dial knob is on 0 and my POA and POI are the same at 100 yards. If I dial on my 500 yard dope and do hold overs then that is what it is. Not zeroing at 500 yards. I am not resetting my dial to zero at 500 yards.
 
Why do people consider dialing on dope zeroing? It's not. You can dial on a certain dope and then use holds from there but it's not zeroing at the range you dialed on.

It's more of a "metaphor" Rob... it's in the context of...from purely a mechanical standpoint.
 
But it's confusing for a new guy asking a question about zeroing distances. It's not a zero for the rifle. It's a way of doing holds. If you were told to put your rifle scope on it's zero at a match would you put on 500 yard data? No. You would dial your knob down to the 0 position where you rifle/scope is zeroed at. Whether it be 100 or 300 or 500 yards. That doesn't matter as the knob is at zero and that is the rifle's zero. Dialing data from that position is just that.

Just trying to answer the question for the OP in the simple terms he asked. Are there times when dialing on 300 or 500 yard data and then using holds is useful? Yup. I have used it many times at matches for multiple target drills using holds. But an actual zero distance is still 100 yards whether the scope is on my 500 yard data or anywhere else off the 0 position.
 
Why do people consider dialing on dope zeroing?

I don't know. It indicates a general sloppiness with language and by extension thought.


Thread officially hijacked! TimActual; good question, probably should go with 100yds, be safe, have fun, aim small.
 
It's more of a "metaphor" Rob... it's in the context of...from purely a mechanical standpoint.
You're right, it's in the context of what impact range the number "0" on your dial is set for, thus the term "zeroing". This ain't rocket science.
 
Why do people consider dialing on dope zeroing? It's not. You can dial on a certain dope and then use holds from there but it's not zeroing at the range you dialed on. Your elevation knob is not on 0. Your zero is when your elevation knob is on 0 and you have POA/POI at whatever distance you have it set for. As I said my rifles are zeroed at 100 yards. My dial knob is on 0 and my POA and POI are the same at 100 yards. If I dial on my 500 yard dope and do hold overs then that is what it is. Not zeroing at 500 yards. I am not resetting my dial to zero at 500 yards.
Is it a matter of definition or is it a matter of semantics? Is a 'zero' the point at which your POI and POA are the same at your crosshairs, or is it not a 'zero' until you slip the elevation knob to the numeral 'O'?
 
But it's confusing for a new guy asking a question about zeroing distances. It's not a zero for the rifle. It's a way of doing holds. If you were told to put your rifle scope on it's zero at a match would you put on 500 yard data? No. You would dial your knob down to the 0 position where you rifle/scope is zeroed at. Whether it be 100 or 300 or 500 yards. That doesn't matter as the knob is at zero and that is the rifle's zero. Dialing data from that position is just that.

Just trying to answer the question for the OP in the simple terms he asked. Are there times when dialing on 300 or 500 yard data and then using holds is useful? Yup. I have used it many times at matches for multiple target drills using holds. But an actual zero distance is still 100 yards whether the scope is on my 500 yard data or anywhere else off the 0 position.

I hear you bro but I was once a new guy and trying to understand the optic as a gearbox (which it essentially is) is what helped me understand the different zeroes and how they worked. Believe me I'm not arguing with you my friend...just adding a different perspective. The mechanical position of the gears will always be in the same spot for a given distance, regardless of what's displayed on the turret. You can grind the numbers off of it and paint your own numbers on and it won't matter. I'm simply saying that if you know your dope, and have a 100 yd zero (as defined by the masses) you can dial to any other "spot" lets call it, and not have to re-live the "zero" process and manipulate the turret display in relationship to the gears...simply because you want to shoot holds from another distance.
 
I'm out. Good luck OP.
 
Yes choover23, that is my biggest regret about my scope, not having the zero stop.

Regarding the discussion dope and zero. Personally I was not confused by that, I realized the distinction there. While granted it may not be best practice to use a common term to signify another meaning, I think that it's the context that matters and tells the difference. Basically from my perspective no harm done and I do really appreciate all of your help. I have learned not just where I'm going to zero my scope to, but some terms and nuances as well. If I'm in the field and hear someone talking about zeroing distances from their dope I will get that now. I think anyways. So even that to me was helpful. But reverse-image zero?... I actually think I understand that concept too!

I think all you guys are great and I'm feeling pretty lucky right now to have found this place, where from my perspective you all sound a lot like family.

Best regards, Tim
 
Depending on your application and what you need the rifle to do and how you are going to run it. That being said my variable power optics for my short and medium action calibers, I set my zero at 100 yards. For an AR Travis Haley did an interesting youtube for the .223 cal.

Find what works or you and your application.
 
Some of the posts here are confusing iron sight techniques (zero, true zero, battle sight zero) with the application to a scope with target/tactical turrets. "True zero" is your setting for a specific range under ideal weather conditions, "Zero" is your setting for a specific range and weather conditions (including windage), and "Battle Sight Zero (BZO)" is your setting for engaging targets out to max point blank range. These terms do not transfer well to scopes because when we say "zero" on scopes, we're referring to "zero mils/moa up" and literally the "0" marking indicator on the scope.

When you can dial your necessary sight setting for a specific range and conditions, it is best to have that setting at your closest nominal range to where you will only have to dial up for your shots. Hence why with most centerfire rifles, it's recommended to go with a 100yd/m "zero", then you reset your turrets to the "0" marking as a handy reference to where the baseline is. This is also why "zero stop" devices were introduced allowing the shooter to easily be able to identify their baseline starting point.

OP, if you try to set your scope for a middle ground zero setting, you're forced to dial both directions and it's easy to get confused, be a full revolution off, and put your shot nowhere near where you want it to be.
 
If you are walking around, shooting between 100 and 1000, then dial your 500 zero.

THIS ^^^

The midpoint of your typical ranges at which you shoot. If you typically shoot from 100 - 500 yards, set for 300.

However, most people shoot at the same range most all the time. In that case, set zero for that distance.
 
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Some of the posts here are confusing iron sight techniques (zero, true zero, battle sight zero) with the application to a scope with target/tactical turrets. "True zero" is your setting for a specific range under ideal weather conditions, "Zero" is your setting for a specific range and weather conditions (including windage), and "Battle Sight Zero (BZO)" is your setting for engaging targets out to max point blank range. These terms do not transfer well to scopes because when we say "zero" on scopes, we're referring to "zero mils/moa up" and literally the "0" marking indicator on the scope.
Maybe I'm missing something, but those terms transfer just fine to use with optics.

My point was, and still is, that it makes no sense to say that I am not zeroed with an optic unless and until I slip my elevation knob indicator to zero because: First, even when I do that the rifle may not be properly zeroed; and second, my elevation knob indicates at a '0' marking every five or ten revolutions - so if 'zeroed' means slipping the knob then I would be incapable of zeroing a rifle without having a scope equipped with a zero-stop.
 
I like 100m because there is little atmospheric affect on the trajectory of the rounds that I shoot. Then I true drop at many ranges to calibrate my trajectory algorithm. Wind is a tricky thing and if I zero at say 300m or 500m it's hard to say that my horizontal dispersion in due to optics adjustment or atmospheric conditions. I then adjust the elevation on my optic based on the estimated dispersion of targets.

For example I zero my 3gun carbine at 50m (this will give me the greatest chance of a hit at the ranges I expect to shoot and the target size I expect to shoot at) and check horizontal at 100m. I then check drop/elevation at several distances however I don't really concern myself with horizontal zero because it may just be wind blowing my 77gr around.
 
Zero = a single reference point that all other distance adjustments are relative to, cornerstone, point of beginning, first station, point of reference. Adjustment still has a range with a single starting point.

100 yard zero noted by the zero stop/zero mark on the turret is what I use to keep things consistent for bolt action rifles. If you create a drop plot, identify your acceptable "kill zone" size, it could be possible to calculate a more ballistically optimal zero with a given distance span but the pay off does not exist for me. 100 yards, call it good and most importantly go shoot it.
 
Graham,

I'm only trying to simplify the terminology and relate it to what the context is here. I worked the ranges at Parris Island for two years teaching recruits how to come up with zeros and true zeros for each yard line and weather condition, and yes we could use the same terminology here, but that's not what the OP was asking. You'll hear on an iron sight KD/HP firing line "What's your zero for the next stage", but in precision tactical shooting we typically hear "What's your setting for the next stage/target". He was asking in the terms of what distance he should use as his baseline on his scope.

I know your point and I can understand it, but new shooters may not. Yes, by definition a "Zero" is any sight setting that allows for POA/POI shots in a specific condition and range. I'm only trying to leave it into the context of the original question and how it is applied with our styles of equipment instead of splitting hairs over one definition of the term. There's more than one definition in this case.

I agree, just because you slip the knob back to the "0" setting, you still may not be zeroed, but you still use that baseline as your setting for developing your drop chart based on downrange performance and we still try to get it as close as possible for a 100yd setting as we can.

Yes, zero stops made it easy but let's be honest here, on scopes not equipped with those you have some form of marking for what rev your scope is on for baseline 100yd setting, don't you? I know I've busted the silver Sharpie out many times myself on the Leupolds and SWFA SS scopes we use at work. Then a setting on a 5mil/rev scope would be considered something like "3.4-1 up" or a flat out "8.4 mil", depending on the shooter and their own technique. It's still not passing the "Zero" every revolution because it's hitting the "0" mark.
 
On a side note...
You mentioned the rifle was for ELR, and your standard load was FGM 168's.
You might want to use FMG 175's if you can find them. They will be good for around 1K + or -. Not exactly ELR, but farther than what you'll get with 168's.

I like a 100 yrd zero because it's more practical. I can see the holes and there's less wind effect to compensate for!
 
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This is a pretty interesting topic for me, as I'm pretty much a math nerd about this.

I think to get the most accurate zero, you need to start with the scope itself. If its a mil dot based reticle, then get make a target that is exactly what your reticle is 'supposed' to be. What I mean by that is that to get the exact distances you expect to see, and to use the reticle for ranging a ukd target, then making sure that you know what 1mil looks like at 100m. The trick will be with second focal plane optics, as they on,y range at one magnification setting, and not two.

Once you have determined your exact range to the target, then you can get your zero.

Now, if you're shooting long range, then you need to make sure that you know what the bullet is doing at distance. If you're using a ballistic solver, then it's easy: make sure you have good data about the rifle, make sure you have good weather data, and then make sure you have good data about the ammo. Using a kestrel will help you get pretty accurate about the weather data. Right now, you shouldn't care about the wind too much, just get the elevation correct for your data. The farther out you can get this, the better.

I zero at a pre-determined distance. That I can figure out based on my reticle. Then I check that against a known target size. Both of these are mil-based because that's what reticle I have in my scope. Again, it's not about the adjustments in your scope, it's about the reticle in your scope.

Next I go to a farther distance, either 500 for a 223 or 750-800 for a 762. These distances have to be pretty accurate, but unless you have a known target size, then you will need a LRF to get it right. + / - 2meters won't hurt anything, but get it close.

Now, put all that data into your ballistic solver, and then it should spit out a answer for you.

Congratulations, you've just tried the first curve.


The short answer here is that it doesn't matter what distance you zero at, so long as you then get an accurate curve for what your particular rifle/ammo/environmentals package is doing.
 
This is a pretty interesting topic for me, as I'm pretty much a math nerd about this.

I think to get the most accurate zero, you need to start with the scope itself. If its a mil dot based reticle, then get make a target that is exactly what your reticle is 'supposed' to be. What I mean by that is that to get the exact distances you expect to see, and to use the reticle for ranging a ukd target, then making sure that you know what 1mil looks like at 100m. The trick will be with second focal plane optics, as they on,y range at one magnification setting, and not two.

Once you have determined your exact range to the target, then you can get your zero.

Now, if you're shooting long range, then you need to make sure that you know what the bullet is doing at distance. If you're using a ballistic solver, then it's easy: make sure you have good data about the rifle, make sure you have good weather data, and then make sure you have good data about the ammo. Using a kestrel will help you get pretty accurate about the weather data. Right now, you shouldn't care about the wind too much, just get the elevation correct for your data. The farther out you can get this, the better.

I zero at a pre-determined distance. That I can figure out based on my reticle. Then I check that against a known target size. Both of these are mil-based because that's what reticle I have in my scope. Again, it's not about the adjustments in your scope, it's about the reticle in your scope.

Next I go to a farther distance, either 500 for a 223 or 750-800 for a 762. These distances have to be pretty accurate, but unless you have a known target size, then you will need a LRF to get it right. + / - 2meters won't hurt anything, but get it close.

Now, put all that data into your ballistic solver, and then it should spit out a answer for you.

Congratulations, you've just tried the first curve.


The short answer here is that it doesn't matter what distance you zero at, so long as you then get an accurate curve for what your particular rifle/ammo/environmentals package is doing.

I don't see what any of what you said has to do with zeroing a gun.
 
Some of the posts here are confusing iron sight techniques (zero, true zero, battle sight zero) with the application to a scope with target/tactical turrets. "True zero" is your setting for a specific range under ideal weather conditions, "Zero" is your setting for a specific range and weather conditions (including windage), and "Battle Sight Zero (BZO)" is your setting for engaging targets out to max point blank range. These terms do not transfer well to scopes because when we say "zero" on scopes, we're referring to "zero mils/moa up" and literally the "0" marking indicator on the scope.

When you can dial your necessary sight setting for a specific range and conditions, it is best to have that setting at your closest nominal range to where you will only have to dial up for your shots. Hence why with most centerfire rifles, it's recommended to go with a 100yd/m "zero", then you reset your turrets to the "0" marking as a handy reference to where the baseline is. This is also why "zero stop" devices were introduced allowing the shooter to easily be able to identify their baseline starting point.

OP, if you try to set your scope for a middle ground zero setting, you're forced to dial both directions and it's easy to get confused, be a full revolution off, and put your shot nowhere near where you want it to be.

redmanss, thanks for your reply and the definitions (something I did not know and is great to know). In what you said you bring up a very good point which definitely affects my decision to choose 100 yards as my "zero" point.

The reason for that choice becomes clear now for a couple of reasons. My initial decision to choose 100 was based on not having to dial in two directions. Now I realize that my 100 yard choice also makes sense if I'm planning to shoot at multiple locations, in that if I chose to "true zero" my rifle further out than 100, I would be hitting more off my center point when conditions change, translating to more off the farther out I shoot.

Plus the practice of using true zero, if I understand that term correctly, doesn't lend itself to long distance shooting, (off a little at zero, off a lot the farther out you go). Additionally (now speaking of "zero"), if I were to decide on choosing a zero farther out then 100 yards, the task of re-zeroing to a new site would become more burdensome due to atmospheric conditions, which have less effect at close range.

Simplicity wins out here and is generally a good idea. Complexity breeds mistakes. At least until I hear some other compelling evidence to make me rethink my decision at this point... THE WINNER IS: 100 YARDS!
 
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I like 100m because there is little atmospheric affect on the trajectory of the rounds that I shoot. Then I true drop at many ranges to calibrate my trajectory algorithm. Wind is a tricky thing and if I zero at say 300m or 500m it's hard to say that my horizontal dispersion in due to optics adjustment or atmospheric conditions. I then adjust the elevation on my optic based on the estimated dispersion of targets.

For example I zero my 3gun carbine at 50m (this will give me the greatest chance of a hit at the ranges I expect to shoot and the target size I expect to shoot at) and check horizontal at 100m. I then check drop/elevation at several distances however I don't really concern myself with horizontal zero because it may just be wind blowing my 77gr around.

Thanks for that, a supporting opinion for my decision
 
I know what Rob meant: That the common understanding is that your 'zero' is the point on the elevation knob that you begin to dial elevation and record your data 'up' in order to shoot at a greater distance than the setting you have chosen to start from.

Defining it that way might make it easier for a novice to understand what he has already done, but it doesn't really do the concept of a 'zero' any kind of justice when it comes to understanding trajectory and how to use a gradiated reticle, because what is being described is more accurately an arbitrarily chosen reference setting on the optic.
 
On a side note...
You mentioned the rifle was for ELR, and your standard load was FGM 168's.
You might want to use FMG 175's if you can find them. They will be good for around 1K + or -. Not exactly ELR, but farther than what you'll get with 168's.

I like a 100 yrd zero because it's more practical. I can see the holes and there's less wind effect to compensate for!

Thanks for the suggestion Robert. When I said ELR, I meant that in context to my rifle/cartridge, where I want to push the limits. For sake of my understanding, if my setup isn't considered capable of ELF, what does constitute ELF? Sheesh, I hope I'm not opening up another can of worms with that question, lol.

Indeed I have read that 175gr will travel farther, and I bought a couple hundred of them to see how I like them. If absolute distance is my goal, would you recommend 175? What would the differential in distance between the two bullets be under say average conditions be? Doesn't have to be a scientific answer, I'm just interested in a ballpark idea of the difference between the two.

Also, would there be a loss of accuracy at shorter distances with the 175. Just from my reading it seems that 168gr is the standard.

Thank you.
 
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Simplicity wins out here and is generally a good idea. Complexity breeds mistakes. At least until I hear some other compelling evidence to make me rethink my decision at this point... THE WINNER IS: 100 YARDS!

I don't feel there is any compelling evidence to suggest anything else. You are not gaining any mechanical advantage to zeroing at any given distance over anoter, the internal travel of the optic remains the same with a 100 yd zero vs a 1K yd zero.
 
Here's why understanding the concept matters to everyone: Elevation is a factor; but it is not the only factor.

Example:

I keep track of two zeros for two different loads for my .308.
Do they print to different POIs at 100m? Yes.
Is there a discernible elevation difference at 100 between the two loads? No.
So I don't change the elevation 'zero' between them at 100m.
Why? Because the trajectory of the .308 between the two loads is probably within a bullet diameter at that distance.
But are my zeros different for the two loads? Yes: The second load prints .3 Mils left of the first one at that distance.
So my 100m zero is .3 Mils left for the second load.
Now, how far left does the second load print from the first one at 500m?
You guessed it: .3 Mils. The same amount as the difference at 100m.
 
I don't see what any of what you said has to do with zeroing a gun.

Keep the end result in mind. If you aren't worried about getting an exact zero distance from the get go, then that .1 mil you neglected here can be the difference between a hit and a miss at longer ranges.
 
THE WINNER IS: 100 YARDS!

Careful here. 100yards is actually 91.4 meters. 1000yards is actually 914 meters. The difference is small at 100, but is the difference between hit/miss at 1k.

If you're looking through a mil-based reticled scope, then it's best to keep it all metric.... Kinda like how we enjoy mil-based adjustments with mil-based reticles. No sense in following it up by switching to yards now, is there....

Just eliminate variables and make things simple. Keeping it all metric will assist in keeping it simple.
 
I don't feel there is any compelling evidence to suggest anything else. You are not gaining any mechanical advantage to zeroing at any given distance over anoter, the internal travel of the optic remains the same with a 100 yd zero vs a 1K yd zero.

When I first posted my question, the only reason that I could think of to the contrary for choosing a 100 yard zero, was that if you were to zero, either at, or more towards the middle of the maximum range you planned on shooting at, that you would be able to reduce the number of physical clicks that would be necessary to hit any target within that range.

I was looking for reasons that people didn't do that. Indeed I found those reasons.
 
Here's why understanding the concept matters to everyone: Elevation is a factor; but it is not the only factor.

Example:

I keep track of two zeros for two different loads for my .308.
Do they print to different POIs at 100m? Yes.
Is there a discernible elevation difference at 100 between the two loads? No.
So I don't change the elevation 'zero' between them at 100m.
Why? Because the trajectory of the .308 between the two loads is probably within a bullet diameter at that distance.
But are my zeros different for the two loads? Yes: The second load prints .3 Mils left of the first one at that distance.
So my 100m zero is .3 Mils left for the second load.
Now, how far left does the second load print from the first one at 500m?
You guessed it: .3 Mils. The same amount as the difference at 100m.

I see the reason in having separate zero data that you could use for different loads, as that would save you time. Noted, especially as I do have some 175gr I bought.