Does it matter what distance you zero at with a mil dot scope?

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zebra

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Sep 29, 2015
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I was going through my quarterly re-zeroing on all my air guns this week and due to some space limitations of where I was at the time, I zeroed one of my guns at 20 yards instead of the 35 or 40 I usually use.

After testing and making a mental note of the holdover / holdunder at various distances the following day, I couldn't find any disadvantage to what I'd done. 

The drop was a few mil dots lower at the extreme end of the guns distance capability but with it being an airgun, I was far from running out of dots at any distance I could be accurate at. If anything, I found the initial zeroing process a little easier at that distance. 

Does anyone have a view on this? Or some info on why it is better to zero further out etc?
 
"Slayerious"I agree with you, just zero it and print out the intercepts.
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What distance do you zero at?

It has me wondering if there is a minimum distance you can effectively zero at.

A quality air gun will put pellets in the same hole (if fired indoors from a stable position etc) but only up to a certain distance. Even with the best airguns, that distance is fairly short. 

At 50 yards, 1/2" groups being just possible is considered good but in reality, it means that the POI is slightly different for every shot so, how do you know where to set your zero? You can take an average of 5 or 10 shots but it still means there is no point where the poi is in the center of the crosshairs for every shot.

if you dial back the distance until your air gun can put every pellet in the same hole then you can set your zero and you know it's correct when the poi is in the center of the crosshairs for every shot. That might mean zeroing at 10 yards for some guns and 30 for better ones.

I was expecting the shorter zero to increase the margin of error at longer ranges but so far I haven't see that. I was using my Mutant Shorty and so far the holdovers have been consistent like they were before.

 
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I guess it depends on what you are shooting to some extent too. If you just need to hit the kill zone of a large animal, you might find that it is covered by the first three mil dots so you could just point and shoot. 

if you want more precision (as I need for small game hunting), you have to learn the holdovers / under for your scope/ rifle/ ammo combo.

I always though it would be good if someone made a scope with independently adjustable target dots. I.e. Instead of adjusting just one crosshair, you would have 4 or 5 dots that you could position yourself for distances of your choice. 

It's not like with powder burners where you set it up for one cartridge. There is a lot more variation with air guns. Being able to map your exact trajectory would make a scope easier to use than relying on mildest in a fixed position.
 
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For a target shooter it is best to zero at the range of the target, that should be obvious.

For a hunter there are two common approaches to zeroing. One is to zero at the range where you have one zero and always hold over. In your ballistics software you establish your zero range such that the pellet rises to line of sight and then drops back below it. Under those conditions you never have to hold under your target at any range. For most air rifles that zero will fall close to 25 meters.

The other is to zero at a range which gives you a near zero and a far zero. The trajectory of the pellet rises from the muzzle to line of sight and then continues to rise above line of sight to 1/2 of the diameter of the kill zone. At that point the trajectory again falls to line of sight and finally out of the kill zone. The point blanc range is the area where the pellet is within 1/2 the diameter of the kill zone relative to the line of sight. For most air rifles that will be an area about fifteen or twenty yards long on a target the size of a squirrel, larger for larger targets with larger kill zones.

Either way you can still use your mil dots for hold off.

I'll do a Charigun video on this topic in the next couple of days as it will be easier to explain it with the graphics that the software provides.

Also there is a range which is too close to zero your scope. As the range decreases there comes a point where the pellet is always below the line of sight. Zeroing at such short ranges would require a "hold off" to get a zero. There is a "sweet spot" for zeroing where the range is long enough to show up shooter errors and short enough to not be affected too much by weather and wind. Also you can zero at a shorter range and by the use of software compute and dial in a turret correction which will move your zero to a different range. This presumes you have a scope of sufficient quality (or you know your scope well enough) to correctly make that adjustment.
 
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For me it depends on the distances I will shoot. I use higher magnification for longer shots so I can be as pin point as possible. I make sure My zero will allow me to use the magnification I like at my furthest distance I will shoot and still have subtensions to use for my hold over. 

I use a pbr zero for all my shooting that doesnt include extreme ranges. 
 
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Yes, it does. I chronograph and then plot the sight-in distance using ChairGun. I like to keep the pellet in the 1/4" kill zone for the longest distance. Using the H&N Baracuda Green pellet with my AA TX200, that sight-in distance is 18 yards. At this distance I'm good to go from 15 yards thru 30 yards with no holdover/under to consider. If I don't have 18 yards available then I use the mil-dots rather than the crosshair to sight-in. I can use a holdover of 1 mil-dot at 12 yards or a holdover of 2 mil-dots at 9.5 yards. When the 18 yards sight-in distance becomes available I can use the crosshair and make sure that I'm on target. If I'm not on target, then something is wrong and I need to check the information that I input to ChairGun. 

 
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"gamyrick"Yes, it does. I chronograph and then plot the sight-in distance using ChairGun. I like to keep the pellet in the 1/4" kill zone for the longest distance. Using the H&N Baracuda Green pellet with my AA TX200, that sight-in distance is 18 yards. At this distance I'm good to go from 15 yards thru 30 yards with no holdover/under to consider. If I don't have 18 yards available then I use the mil-dots rather than the crosshair to sight-in. I can use a holdover of 1 mil-dot at 12 yards or a holdover of 2 mil-dots at 9.5 yards. When the 18 yards sight-in distance becomes available I can use the crosshair and make sure that I'm on target. If I'm not on target, then something is wrong and I need to check the information that I input to ChairGun. 


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I don't understand. I mean... I understand how you use Chairgun. I don't understand why you think it matters what distance you zero at (assuming you have enough mil dots to cover the range you shoot at). 

If I zero at 30 yards, for example, I know the poi will be X dots down at 10 yards and X dots down at 50 to 100 yards etc. I know the holdover / under will be different if I zero at a different distance but why should that matter (as long as I have mapped it out)?

Are you saying that you need to zero at a certain distance to be able to use chairgun as you want or are you saying there is a specific advantage or disadvantage to not zeroing at the distances you mentioned?

I usually don't mind if the POI is in the center of the crosshairs or 2 dots down as long as I know what it is for the distance I am shooting at. Even if the zero is not at the distance I most commonly shoot at I find the mildots to be an effective compensator. My point here was that I find it easier to zero a scope at shorter ranges but I haven't yet found a disadvantage. Most people seemed to zero at 30 or 50 yards so I was wondering what advantage there was.

 
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Zebra,

All my rifles have just one zero: the upper apex of the projectile. That zero is my sight in distance for that rifle. Everything is then holdover (if you are into that) or dialing back down the elevation turret if you are a dialer like me. This is the tape for my elevation turret on my AirWolf MCT (same as in my avatar) It is zero'd at 28 yards. My 177's are at 25 and 26 yards. I haven't done enough work with the RAW 30 to know its yet. Black is going up to the zero, red is coming back down from the zero and green are the click counts from the turret for Strelok Pro once I get past 68 yards. The purple is yardage one full dial down off the zero. When the turret is set on the zero, the scope pointer touches the bottom of the black number. That's how I can immediately tell by looking at the pointer and numbers if the turret is in the correct rotation. 

The scope is 1/8 MOA clicks, so you can see it's pretty flat from 18 yards (.2" low from crosshairs) to 41 yards (.5" low) so in a pinch point, hold over a touch and pull trigger. No mil dots needed for that.

So there is my secret receipe for zeroing a gun and setting up a its scope.



 
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"sharroff"Zebra,

All my rifles have just one zero: the upper apex of the projectile. That zero is my sight in distance for that rifle. Everything is then holdover (if you are into that) or dialing back down the elevation turret if you are a dialer like me. This is the tape for my elevation turret on my AirWolf MCT (same as in my avatar) It is zero'd at 28 yards. My 177's are at 25 and 26 yards. I haven't done enough work with the RAW 30 to know its yet. Black is going up to the zero, red is coming back down from the zero and green are the click counts from the turret for Strelok Pro once I get past 68 yards. The purple is yardage one full dial down off the zero. When the turret is set on the zero, the scope pointer touches the bottom of the black number. That's how I can immediately tell by looking at the pointer and numbers if the turret is in the correct rotation. 

The scope is 1/8 MOA clicks, so you can see it's pretty flat from 18 yards (.2" low from crosshairs) to 41 yards (.5" low) so in a pinch point, hold over a touch and pull trigger. No mil dots needed for that.

So there is my secret receipe for zeroing a gun and setting up a its scope.



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Does your rifle put every pellet in the same hole at 28 yards or 25 yards? I'm not sure mine do. My better guns are fairly close to one hole at 25-28 but there is still a small variation.

How do you deal with the variation in poi if they aren't one hole at the zero distance? Are you taking the average POI based on a 5 or 10 shot group or some other method?

I'm not sure I understand what the spreadsheet means. It looks like a Sudoku puzzle to me (and I'm not good at those). I memorize holder overs for a range of distances because I have a great memory but poor mental arithmetic. I'm also a hunter and not a target shooter so the speed at which I can aim and shoot is important. Squirrels don't wait for me to adjust turrets before I shoot them in the head which I think is a little rude of them.

Why do you care if there is a holdover vs a hold under? Is there an advantage to only using the mil dots below the crosshairs? They look the same to me. 

 
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Zebra,

Yes, my air rifles are all one hole shooters at 30 yards. Here is an old .177 target where I was doing pellet head size testing at 50 yards. With 4.50 or .451 sized pellets my field target guns shoot into like 1/4" (AZ Steyr) and 3/8" (AZ CR-X) at 50 yards. (the size of the red dots is 1/4). The Airwolf MCT .22 and RAW HM 1000x .30 stack pellets at 50 yards as well.



Those numbers above are the pellet head sizes from .446 to .453. See how open the .446 group is? So, to get one hole I need .450 or .451 pellets. If I shot from the tin (those are all from the same tin). I'd get 'fliers" and open groups.

If I did have a gun that had POI variation at that 30 yards, I'd be working on pellet sizing/weight/shape/brand testing -like the above - to get rid of the variation (if I were target shooting) Then I'd give away all the pellets that didn't shoot well (like I just did here last week) If I could not get rid of the variation, depending on the POI spread, I'd shoot groups to find the average POI and use that. The bigger the variatio the more pellets I'd use per group.

Lol, that is no suduko puzzle, and there is no math. That tape wraps around my elevation turret like in my avatar. Look at the far left bottom of the scope tape. That black 10 is 10 yards, then to the right, 11 yards, and so forth. The first red number on the far right is 29 yards right above the black 27 yard. So, turn the elevation turret so the pointer lines up with the scope tapes target yardage and the cross hairs will be exactly where the pellet will hit.

The mil dots over and under will look the same because they have to be in order to be effective tools for compensating for distance. The only advantage to having the scope zeroed at the apex for mil dots is everything is hold over and there is no hold under numbers to remember. And you'll also get yardage pairing that way. Looking at my tape, the hold over for 11 and 63 yards is the same as is 13 and 55, 16 and 46, 18 and 41, then all the numbers line up. One would only have to memorize ten or so combos to use hold over effectively from 11 to 63 yards on my gun.

And in my case from 18 to 41 yards I know that I wouldn't need much hold over at all. 1/4 low at 18, on at 28, and 1/2 low at 41 is about all I'd need for backyard type shooting.

The big advantage to doing it my way (dialing) is that it doesn't matter if my scope is set at 10X or 50X or somewhere in between. The cross hairs will still be exactly on target. With mildots and hold over, they are only accurate at the distance the scope was calibrated/sighted at. On a fixed power scope, no issue. On variable power, which most of us have, the mil dots are calibrated typically at the lowest power. That's why chair gun / strelok asks for the minimum magnification, calibration magnification, and current magnification.

Let's use a real example. If I were aiming at a squirrel 53 yards away, my gun with its current settings and scope set at 10x I would hold over by 1 mil dot and be exactly on target. If my scope were at 20x, I'd now need to hold 2 mil dots over to hit the same target. At 30x, it's now 3 mildots. At 40x 4 mil dots and at 50x 5 mil dots. So I'd not only have to know the table for pellet drop, I'd have to be doing the math to get the mil dot holding right based on my current scope magnification (or carry a phone with Strelock). I'd rather know the yardage, turn the turret, center the cross hairs, and hit the target regardless of my magnification. Mil dots also work well when you are consistently shoot a target of the same size and can use the mildots to get an approximate distance to the target (deer, man, etc). For example something that is 2 mil dots high at 50 yards is only going to be 1 mil dot high at 100 yards (given the same magnification again). I don't think you'd find many military snipers using that approach though; given enough time for their shot, they are turret twisters.
 
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"sharroff"Zebra,

Yes, my air rifles are all one hole shooters at 30 yards. Here is an old .177 target where I was doing pellet head size testing at 50 yards. With 4.50 or .451 sized pellets my field target guns shoot into like 1/4" (AZ Steyr) and 3/8" (AZ CR-X) at 50 yards. (the size of the red dots is 1/4). The Airwolf MCT .22 and RAW HM 1000x .30 stack pellets at 50 yards as well.



Those numbers above are the pellet head sizes from .446 to .453. See how open the .446 group is? So, to get one hole I need .450 or .451 pellets. If I shot from the tin (those are all from the same tin). I'd get 'fliers" and open groups.

If I did have a gun that had POI variation at that 30 yards, I'd be working on pellet sizing/weight/shape/brand testing -like the above - to get rid of the variation (if I were target shooting) Then I'd give away all the pellets that didn't shoot well (like I just did here last week) If I could not get rid of the variation, depending on the POI spread, I'd shoot groups to find the average POI and use that. The bigger the variatio the more pellets I'd use per group.

Lol, that is no suduko puzzle, and there is no math. That tape wraps around my elevation turret like in my avatar. Look at the far left bottom of the scope tape. That black 10 is 10 yards, then to the right, 11 yards, and so forth. The first red number on the far right is 29 yards right above the black 27 yard. So, turn the elevation turret so the pointer lines up with the scope tapes target yardage and the cross hairs will be exactly where the pellet will hit.

The mil dots over and under will look the same because they have to be in order to be effective tools for compensating for distance. The only advantage to having the scope zeroed at the apex for mil dots is everything is hold over and there is no hold under numbers to remember. And you'll also get yardage pairing that way. Looking at my tape, the hold over for 11 and 63 yards is the same as is 13 and 55, 16 and 46, 18 and 41, then all the numbers line up. One would only have to memorize ten or so combos to use hold over effectively from 11 to 63 yards on my gun.

And in my case from 18 to 41 yards I know that I wouldn't need much hold over at all. 1/4 low at 18, on at 28, and 1/2 low at 41 is about all I'd need for backyard type shooting.

The big advantage to doing it my way (dialing) is that it doesn't matter if my scope is set at 10X or 50X or somewhere in between. The cross hairs will still be exactly on target. With mildots and hold over, they are only accurate at the distance the scope was calibrated/sighted at. On a fixed power scope, no issue. On variable power, which most of us have, the mil dots are calibrated typically at the lowest power. That's why chair gun / strelok asks for the minimum magnification, calibration magnification, and current magnification.

Let's use a real example. If I were aiming at a squirrel 53 yards away, my gun with its current settings and scope set at 10x I would hold over by 1 mil dot and be exactly on target. If my scope were at 20x, I'd now need to hold 2 mil dots over to hit the same target. At 30x, it's now 3 mildots. At 40x 4 mil dots and at 50x 5 mil dots. So I'd not only have to know the table for pellet drop, I'd have to be doing the math to get the mil dot holding right based on my current scope magnification (or carry a phone with Strelock). I'd rather know the yardage, turn the turret, center the cross hairs, and hit the target regardless of my magnification. Mil dots also work well when you are consistently shoot a target of the same size and can use the mildots to get an approximate distance to the target (deer, man, etc). For example something that is 2 mil dots high at 50 yards is only going to be 1 mil dot high at 100 yards (given the same magnification again). I don't think you'd find many military snipers using that approach though; given enough time for their shot, they are turret twisters.
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When I asked if they were "one hole", I didn't actually mean "one hole". This is my fault for not being specific. What I actually meant by one hole was every pellet landing in exactly the same spot. The .45 group in the pic is a tight group and it is indeed "one hole" but still has a visible difference in the poi to create a ragged hole vs a hole where you could not tell if it was a one shot or ten shot group.

I get similar size groups from my Mutant. It's actually the only gun I have that arrived shooting like that out of the box. The experiment I did was to dial back the distance to zero at the point where there was no longer any visible variation in the poi. I.e. One pellet sized hole.

You seem like you have an effective and well thought through approach to zeroing your guns. If you have the time, I would be interested to see how you get on with repeating my experiment to see if it gives you the same results, better results or worse ones.
 
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Zebra,

At 30 yards, my pellets will go through the same one rough hole (little bigger than the pellet itself) from my benchrest. I've never put 10 pellets through 1 hole at 30 yards and not been able to tell it's not a single pellet. There is always that whisp of wind, thermal happening, downdraft, variation in pellet, unlucky flying bug that took at hit, etc that pushes each pellet a little up/down or left/right.

Re your experiment of sighting at 20 vs 40, with my gun you would get the same trajectory and result as long as the 20 was your first zero and 40 was your far zero. To check this, go back up in the post and look at my scope tape. The black 20 yard zero is right below the red 39 yard zero. Now I'd say that at 40 you have twice the distance to refine your dial in (maybe you'd add another click of up/down or right/left after you see where it lands at 40 that you might not have seen at 20. Same at going our to 80.

This might better help you visualize what the tape looks like and how it gets used on the gun. The turrent is dialed in for 17 yards (side wheel match) but it would also be on at its second zero at 43 yards.



 
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"sharroff"Zebra,

At 30 yards, my pellets will go through the same one rough hole (little bigger than the pellet itself) from my benchrest. I've never put 10 pellets through 1 hole at 30 yards and not been able to tell it's not a single pellet. There is always that whisp of wind, thermal happening, downdraft, variation in pellet, unlucky flying bug that took at hit, etc that pushes each pellet a little up/down or left/right.

Re your experiment of sighting at 20 vs 40, with my gun you would get the same trajectory and result as long as the 20 was your first zero and 40 was your far zero. To check this, go back up in the post and look at my scope tape. The black 20 yard zero is right below the red 39 yard zero. Now I'd say that at 40 you have twice the distance to refine your dial in (maybe you'd add another click of up/down or right/left after you see where it lands at 40 that you might not have seen at 20. Same at going our to 80.

This might better help you visualize what the tape looks like and how it gets used on the gun. The turrent is dialed in for 17 yards (side wheel match) but it would also be on at its second zero at 43 yards.



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What you are saying about 20 vs 40 yard zero is the question I have. i.e. Does the extra adjustment potential at 40 yards really help or does the natural variation in poi at that distance just have you chasing your tail trying to adjust for every random variation to your zero?

At 40 yards, shot 2 might land a fraction to the left or right of shot 1. It's still one hole but not exactly the same hole. If you adjust the zero to put the crosshairs exactly on the poi for the last shot then it will still vary again for the next shot etc. plus, the further out you go, the more influence there is from the wind.

My assumption was that zeroing at 40 yards would yield better results than 30 but now I am not so sure. With a gun like my Mutant (and I'm sure your accurate guns will be the same), if I zero properly at 20 or even 15 yards, the poi only seems to go up or down at different distances (without wind). 

The other point is that just because you zero at 20 yards or 15 yards, doesn't mean you'll miss any potential fine tuning opportunities further out because I usually test my zero at multiple distances regardless of where it was set. E.g. If I zero at 15 or 30 yards, I then take shots at 40, 50, 70 and 100 yards to map the the trajectory and check I am actually hitting what I am aiming at.
 
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My opinion is that yes the extra distance helps, especially for left and right correction. I don't mind a little variation, I just want to make sure I'm not more than a 1/8 MOA click off be cause that is my granularity in adjustment and I can fix that. I check my .177's from 1-55yards in 1 yard increments for FT, and I did the same on the .22 out to 68 yards. I'll probably do the .30 out to 100. I figure if one is going to practice, might as well do it at different yardages and update the scope too. It would be really tedious if I was shooting at a stationary target that I had to move each time, but I rigged a target platform on a remote control rock crawler. Move it a yard, check with range finder, shoot. Crawl another yard, repeat. It's quick work that way.



 
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Yep, that is a remote controlled rock crawler that I adapted to carry a target around in the the woods you see out that window. It's way easier that moving the target around manually (look to the left of the bottom left red dot and you will see my manually placeable target) and is great practice for figuring out distance, ranging the scope correctly and taking shots at random distances.
 
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"sharroff"Zebra,

All my rifles have just one zero: the upper apex of the projectile. That zero is my sight in distance for that rifle. Everything is then holdover (if you are into that) or dialing back down the elevation turret if you are a dialer like me. This is the tape for my elevation turret on my AirWolf MCT (same as in my avatar) It is zero'd at 28 yards. My 177's are at 25 and 26 yards. I haven't done enough work with the RAW 30 to know its yet. Black is going up to the zero, red is coming back down from the zero and green are the click counts from the turret for Strelok Pro once I get past 68 yards. The purple is yardage one full dial down off the zero. When the turret is set on the zero, the scope pointer touches the bottom of the black number. That's how I can immediately tell by looking at the pointer and numbers if the turret is in the correct rotation. 

The scope is 1/8 MOA clicks, so you can see it's pretty flat from 18 yards (.2" low from crosshairs) to 41 yards (.5" low) so in a pinch point, hold over a touch and pull trigger. No mil dots needed for that.

So there is my secret receipe for zeroing a gun and setting up a its scope.



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Sharroff, I like your process of setting zero at Apex. I get the black up and red down but not understanding how you use the green. I decipher the 60, 70 out to 110. But why doesn't the green 60 correspond to the red 60 point? Also what are the second set of black. Umber sunder the green? They aren't sequential?

Thanks
 
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