At what range should you zero your scope?

By B.B. Pelletier

Where to zero a scope is a question that always starts a friendly conversation among airgunners. I’ll tell what your options are and leave the final choice to you.

Pellets start to fall the minute they leave the muzzle
The moment a pellet (or bullet) leaves the muzzle, it begins falling toward the ground. It falls at the same rate it would if you dropped it from the height of the bore – assuming the bore is parallel to the ground! And that’s where the scope adjustment comes in.

Because a scope looks straight out and because it is mounted above the bore, it can only be made to intersect the trajectory of the pellet if it points down through the ballistic path the pellet takes. And, that is how scopes are sighted-in.

They are adjusted to look straight through the downward arcing trajectory of the pellet at a point close to the muzzle. When the pellet arrives at the spot where the downward-looking scope is pointing, the crosshairs will be exactly where the pellet is and the scope will be zeroed at that distance.

Beyond this point, the scope will actually be looking UNDER THE PELLET’S FLIGHT for a certain distance after the first point of intersection. Then the falling pellet will cross back through the scope’s line of sight once more, intersecting the pellet a second time and creating a second zero point.

How we correct the picture!
Nobody likes to think about their pellet falling, so we elevate the barrel so the pellet is actually going slightly up when it leaves the gun. Now, the whole thing makes more sense.

The pellet SEEMS to be rising when, in fact, it is only doing so because the barrel is tilted slightly up at the muzzle. The downward-looking scope intersects the pellet at some distance downrange, then the pellet SEEMS TO RISE above the straight line of the scope and intersect a second time further downrange.

What’s a good distance to sight-in a scope?
Now that we understand how it works, we need to find the right distance to sight-in. You now understand that the scope will actually be zeroed for TWO DISTANCES instead of one.

For a pellet gun that shoots around 800 f.p.s., I like to sight in at 20 yards for the near distance. The second distance will be around 30 yards, and the pellet will not rise by as much as one pellet diameter at the in-between distances (between 20 and 30 yards). If you sight in at 15 yards with the same gun, the pellet will be back to the intersection of the crosshairs around 40 yards, and it will rise more than an inch in between.

For a gun that shoots 950 f.p.s., I would still sight-in at 20 yards as the near distance but the far distance is now 37 yards or so. For both guns (800 and 950), the pellet will be about one inch below the aim point at 10 yards and will rise to the crosshairs as it approaches 20 yards. At the muzzle, the pellet will be as far below the crosshairs as the bore is below the optical path of the scope, which could be as much as three inches or more!

What if I only want ONE sight-in distance?
It IS POSSIBLE to sight a scope to intersect the pellet only once, but why would you want to? You align the scope to graze the pellet’s trajectory, and after that it’s all down hill!

69 thoughts on “At what range should you zero your scope?

  1. My suggestion for a clickless (or almost holdover) life is to assume a 30Troyer (distance in yards divided by the kill zone in inches) kill zone. This works out to be 1″ at 30 yards, 1/2″ at 15 and 2″ at 60… If you zero at about 3/8″ high at 25 yards (assuming that is the highest point for your pellet) you will be in the kill zone from about 15 to 40 yards. Closer than 15 or farther than 40, aim for the top of the kill zone.

    This assumes you are shooting field target with holes, of course. If shooting game, you really won’t be shooting much at the long distances (and wind will have a much larger effect than pellet drop). For short distances, you are probably fine up to about 12 yards but just aim about 1/4″ high if you have the time to setup the shot.


  2. Joe,

    Thanks for your input. You have a good plan as long as the kill zone (or traget) is of a known size. But it really goes farther than that.

    What Brad Troyer has done is reduce to an easy process or formula the gut instinct a rifleman who knows his gun has for how much aimover to apply. That’s a wonderful way to shoot a gun!

    Our readers should study your comments and try to appy them to their own shooting.

    Thanks,

    B.B.


  3. first question. Does barrel length play a part in this intersection of scope and pellet path?

    second question. When I got my rifle to shoot a target 10 feet away it shot to high at 25 feet. Is there a gun that shoot from 5 feet to 25 feet more accurately. and another that shoot more from 25 feet and above?

    third would a shorter barrel gun be more effective for closer targets.


  4. Barrel LENGTH doesn’t matter. What matters is velocity, and, depending on the powerplant, barrel length affects velocity. Pneumatics and springers go faster with longer barrels. Springers go a LITTLE slower with longer barrels.

    If your gun is sighted to hit dead-on at 10 feet, yes, it will rise at 25 feet. That’s what I was saying in the posting. No gun shoots more accurately at 5 to 25 feet, but if you want a flatter trajectory at that distance, you need a gun that shoots slower.

    A shorter barrel will usually be slower, for the reasons mentioned above. I don’t know if that answers your question or not. It sounds to me like you want a good bug-buster airgun, so watch tomorrow’s post.

    Thanks,

    B.B.




  5. I don’t get it, why don’t you simply sight it in so that the scope is pointed parallel to the bore, but a few centimeters above? In this case you could target shoot, or hunt at all distances, but consider the fact that the scope is a few centimeters above the bore.


  6. Sounds like time to post some links to good ballistics software.

    Chairgun is an excellent choice — it used to be free but the current price is very reasonable and the program is worth every Pound (the author is a Brit and uses the monies for charitable purposes).

    As originally posted, the instant the pellet leaves the barrel it starts to fall and slow down. Hence, it is impossible to have a gun that hits the same spot at any distance without adjusting for this curve (trajectory). Higher sighting (scopes, red dots, etc.) make it worse, not better.

    You can learn to holdover or “click” (use the elevation knob on a scope) but if you shoot at distances from 5 yards to 50 yards, you must learn your gun’s ballistics!

    Best,

    Joe




  7. I like them after they’re on the gun, but they are twice as hard to set up.

    Maybe I’ll do a post about them.

    B.B.


  8. I have to help a friend sight in his chinese air rifle b21 in 22 caliber it was tuned and chrono shows 740 fps 17 ft lbs of energy

    this is with a 14.3 gr pellet

    at 100 feet it still puts a hole in can the same as it does at 30 feet.

    what do you recommend as the two sight points?

    we will be using adjustable rings

    thanks


  9. I would zero at 20 yards for the near point and see how the far point works out. I’m guessing it will be 27-29 yards.

    B.B.



  10. I just bought a GAMO 220 with scope and I read that I should sight in at 20 yards and 40 yards but how do I do that?
    Bob Taylor


  11. Bob,

    The two distances are really from the same sight-in. If you do 20, you also get 40.

    Your scope looks downward through the trajectory of your pellet. The pellet begins falling to earth the moment it leaves the barrel. The downward curved path it follows is called the trajectory.

    A straight sight line that intersects the trajectory at 20 yards, will then drop below the pellet until it has gone 35 to 40 yards, when it will fall down to the sight line again. That’s where the two distances come from.

    B.B.


  12. BB
    Thank you. So if I understand this process, I shoot the rifle at a target, and adjust the scope, until I can consistently hit the bull’s eye at 20 yards. I then get 40 yards too. What happens if I want to shoot at something that is 50 yards away? Do I just estimate the range and guess for longer shots? My scope is a BSAS4x32 and does not appear to be adjustable except by the two adjusting rings under the caps.(in the middle of the scope) I have never used a scope before so I am really in the dark here.
    Thanks for your help
    Bob


  13. Bob,

    With your kind of scope you estimate and aim over. all shots will be lower than you aim point.

    By the way, the second distance may not be 40 yards, but 35 or 37. that is something you’ll have to discover.

    Read the past posts on sighting in a scope. There are quite a few.

    B.B.




  14. Hey BB,

    I’ve been reading alot of the blogs and now have a good idea about the 2 point intersection deal. But what about a parallax adjustible scope. Does this just simply move the two intersection points equally. For ex. If your two intial points of int. are 20 and 37 yards (with the scope parallax at 20 yards) and you adjust the parallax to 30 yards will the two points of int. now be 30 yards and 47 yards. Hopefully this isnt answered in any other blogs or posts previously but i dont think i saw it. If it is just point me to the right blog/post.

    Much thanks, Kyle


  15. Kyle,

    Parallax correction has nothing to do with trajectory. It only correct parallax of the sight. The trajectory remains the same and the two intersection points stay where the are.

    B.B.


  16. having bought an rws 350 and scoping it with the 450 scope i’ve been in left field. Since it is winter-feb07-I’ve been reading as much as as I can about airguns between trips to the range–all of a sudden I can’t get enough-I’ve been bitten hard by the shooting bug! Thanks to your blog I can now properly site my rifle in and have a good idea at what to do when shooting out to 40-50-60 yards-thanks for a great site-sure takes the sting out of those cold days!



  17. B.B.

    First, should I use the winchester 500x for small pests? Second, where should my first point of zero be?

    Thanks a lot.



  18. Now I know what a 500X is.

    It is WAY TOO underpowered for hunting of any kind, unless you have a .22. Then it’s suitable for mice and very small birds out to 20 yards. As a .177, it’s too weak.

    B.B.


  19. B.B.

    Thanks a lot for the info on the 500x.
    Is there any affordable air rifles that shoot at 500fps or bellow that could be used for pest control/small game.

    Many Thanks


  20. 500X,

    Okay, you are either a Canadian or a European.

    Here is how to address the problem. Get a rifle that shootes the largest caliber you can find at or below 500 f.p.s. A .32 caliber rifle would be ideal. But that will cost a bundle.

    Have you considered a crossbow?

    B.B.


  21. B.B.

    Thanks a lot for the info. I was looking for an air rifle, do they make .32 air rifles? Or were you talking about a real fire arm.

    Thanks a lot.


  22. Yes, there are .32 caliber big bore air rifles, but they are being custom made. Last night I spoke to Dennis Quackienbush who makes big bores like this.

    Dennis says he doesn’t want to make airgns for Canada because of all the restrictions shipping to Canada, so you would have to find a Canadian maker. I’m sorry that I do not know of any big bore airgun makers in Canada.

    B.B.



  23. Seeing this exchange over this mystical 500fps limit for airguns in Canada/Europe, I am perplexed at the state of affairs their citizens must deal with.
    It would appear that common sense is not a part of the equation when it comes to that category of regulations there.
    It really is a pity that those regulations weren’t put in place so much to stop guns, as they were to discourage hunting.
    I sincerely wish you luck in your search for something that will fit your needs.

    -Scott


  24. Helo BB, This is my first foray into “big bore airguns” I am purchasing a rifle that is capable of 470 foot pounds with a 205 grain “bullet”, I have a few questions if i will be working with ranges up to 120 or so yards, what would be a good starting “zero point” so that I get the maximum amount of “leeway” such as the 20 yard inital zero point for a 850fps diablo pellet? The “bullet” I would like to shoot has a ballistic coefficient of .189 which is a bit more than your standard diablo pellet, the rifle in question can shoot the 230 grain “bullet” at around 950 fps. I say aproxiamte because the builder of the rifle at the present did not test a 230grain, but the gun will shoot a 205 grain conical at 1020fps, so by my calculation it should shoot the 230 grain at around 950-980 fps for a final energy of around 500 foot pounds or so. Any help would be appreciated thanks, BTW this blog has a lot of really good info. This blog is responsible for me getting back into airguns again thanks.


  25. hi i was wondering if anyone could help me. i have a gamo cfx and got it zeroed when i bought it. last week a took it apart for a major clean after a hunt (11 rabbits and a pheasent, would have been 12 but the little bugger seen it coming). after taking it apart i have tried to zero it myself but im struggling a bit. i was hoping for some input

    you can email me at spitfire.1500@hotmail.co.uk

    hope to hear from someone soon


  26. spitfire,

    You never have to clean an air rifle unless it looses accuracy.

    When you say you took it apart, did you take the action out of the stock or did you disassemble the action? If the latter, you need to send the gun and all extra parts to Gamo U.S.A. for reassembly. And then do ever disassemble it again.

    If you didn’t really disassemble the action, what did you disassemble and what seems to be your problem now?

    B.B.


  27. the mounts that attach to the sight then attach to the rifle where coming loose because the padding was falling apart. i took off the mounts then put tape round the sight so it would have a better grip.
    then when i put the sight back on hte zero was out by a long way.


  28. If the last comment was from spitfire and if you are referring to the disassembly issue with your Gamo CF-X, then I understand that you didn’t disassemble the rifle but simply remounted the scope. No problem there.

    Is that correct, and are you spitfire?

    I am holding numerous conversations on postings all over this blog, and when I have to answer something specifioc, I have to know who I’m talking to and what we are discussing.

    B.B.


  29. Ok..Im new to this air rifle thing, How do you get 2 distances from one scope? and how do i find out the fps of my gun? Ive just got a secondhand Gunpower Stealth. With a simmons deerfield 3x9x50 Scope. Also what is the best kind of range to zero in at? i will be using for vermin hunting mainly


  30. lego-man,

    Unfortunately this posting is the place I would have referred you to answer your question about two sight-in points.

    Friday’s blog will be devoted to answering your question. I will draw diagrams.

    You find out the velocity of your gun (measured in feet per second or meters per second) with a chronograph. Read this article to see how they work:

    http://www.pyramydair.com/site/articles/chrony/

    Your Gunpower Stealth airgun is probably 12 foot-pounds. It will shoot a .177 caliber 7.9-grain p[ellet at about 800 f.p.s. or a .22 caliber 14.3-grain Crosman Premier at about 585 f.p.s.

    Zero the rifle at 20 yards and the pellet will be on target out to about 25 yards. At all other ranges the pellet will shoot below the aim point.

    B.B.


  31. hello, everyone i feel like the stupidest person on earth.i have a crosman 77 elite/ .177 with raptor pellets they say im getting close to 1300 fps. any way my prob, is this. my friend tried to zero in my scope because i never did it before. and now i cant even hit the side of a mountain. any advise as to just getting this scope to a point were i can work with it. thank you for your time ken n.j





  32. The package tells me to sight the scope in at 50 yards. That’s too far. I think I’ve worked this out. I used the ChairGun2 software and I think I will sight it in at 20 yards which will also give me zero at 30 yards. Thanks.


  33. Being a teenage around 20 years ago when my father gave me a benjamin with a scope, I faced this zeroing problem with no one to help me that time. I knew that if I zero it at -let’s say- 20 yards, I’d have to aim higher for object closer than that and aim lower for longer target. But to determine how much lower or higher was not easy.
    So, I solved this myself (considering that I had no available sources that time to do it ‘right’ and I live in Indonesia) by zeroing the scope to INFINITY.
    Yes, this may sound ridiculous. But I want to share it, asking for opinion (especially from you BB), and asking if maybe there is another person who did the same as I did.
    Zeroing to infinity is like this: my scope is about 30mm higher than the airgun’s barrel (now a Sharp Innova), so I zeroed mine always 30mm lower than the crosshair, at any range! This way, I can easily shoot any target within range of my airgun (around 25 yards, I assume the bullet has its best flat trajectory).
    Well that’s said. I am enjoying rat hunting and ’til now I still do what I ‘invented’ some 20 years ago.
    Thanks, Jim.









  34. I am enjoying reading your blog.
    I am thinking of buying an air gun for pigeon and bat control around my home.
    1) My typical shot will be at 20 meters at an angle of 35 above horizontal. Would I expect my point of impact to be high with a scope that is zeroed for a 25 meter horizontal shot.
    2) Could you recommend a minimum muzzle energy that would deliver a fatal shot to a roosting pigeon (and / or bat) from that distance?
    Thanks


  35. Pinche,

    Here is how to deal with elevated shots. In your mind, drop a plumb bob from the target and see how far away the bob is when it is level with you. From your description I would guess you are making a 15 meter shot. So sight in for that range.

    A gun zeroed for 25 meters will be very low at 15 meters. Depending on the velocity maybe more than one inch/25mm.

    Energy for the kill is a lot less than people imagine, if the placement is good. A gun that starts out with 6 foot-pounds can kill a pigeon at 56 yards, as the Urban Hunters proved when they wrote for me in Airgun Illustrated. I don’t think bats need as much energy as pigeons.

    Accuracy is far more important than pellet shape. I always go with domed pellets because they are the most accurate of all.

    B.B.


  36. I just got a new 1000 fps air rifle and when I try to setup the scope it says to shoot at a target 100 metres away.Not sur, but 300 ft seems a bit far for tageting with an air gun. I try to scope in at about 100 ftand I can’t get the scope to go up any higher. Any suggestion? The manual sights work great (within one inch of centre) at this distance.



  37. …which makes me wonder, what scope did you get? And if it’s a cartridge gun scope, is it airgun rated?

    Also, what rifle did you get?


  38. I own a .177 cal air gun that shoots at 1000fps. I have sighted it in for 50yds. and made a ballistic chart for it. it has a leapers 3x9x50 scope on it with a mil-dot reticle in it. so as long as you have those two things you can range with the scopes reticle and reference to the ballistic chart to make your scope adjustment, and your dead on every shot. the formula for finding range using the mil-dot reticle is:
    height of target in yds x1000/height of target in mils= range in yds.

    For you guys that think it would take way too long to make the adjustments on my scope, it takes me about thirty seconds to make adjustments. and if you purchase a mil-dot master or a mil-dot table it takes half that time. Go to Mil-dot.com to learn more.


  39. B.B. Pelletier – Thanks so much for the simple explanation with numbers! I spent over an hour today looking up trajectories and doing a lot of crazy math trying to figure out my best crossing points. 20/40 sounds good. I have about 15/50 right now and am pretty happy with it. Just have to be careful at that pesky 30 yard mark where the pellet is 1.2” high. You are amazingly patient with these questions!
    Kudos!



  40. Michael,

    The PBA ammo is not accurate at any distance past 10 yards. Using the artillery hold, the maximum effective range is the distance at which you can group ten shots inside one inch. With premium JSB Exacts, that should be about 30-35 yards.

    Sight in at 20 yards and you will be within 1/2-inch out to 35 yards or so.

    B.B.


  41. what about the hight of your scope off the barrel,would it come into play also? a small 20mm scope on low rise rings would have a different optium setting than a 50mm scope on high rise rings. It seems trajectory intersections would change with center to center bore/scope plane differences


  42. Scope height does come into play, but it's only critical at short ranges. After 20 yards it pretty much doesn't matter, which is why I ignore it.

    Also, the 20mm scope objective is usually on an inferior optic, so the benefit gets cancelled by the brightness and sharpness of the better glass. But that only holds true when my assumptions are correct. There are vintage scopes with small objectives and good glass that do work much better.

    B.B.



  43. Raceman,

    Why is 20 yards off? Your rifle won't be flat-shooting at any range, but if you sight it at 20 yards it will be flatter at useful airgun distances than if sighted at 10 yards.

    B.B.


  44. I just bought my first air gun and reading this blog was extremely helpful. I understand now the physics behind the trajectory and scope. Good reading, thanks a lot!



  45. When I was a small boy, 55 years ago, my grandfather used to set up a black rubber ball hanging on a string at about 18 yards and tell me and my brother to keep it swinging… Used to aim at the string about an inch above the ball… no scopes back then. When out hunting rabbits his advice was to aim to skim the top of the Rabbits head. I got my fair share of kills with that advice. What was annoying was that my Uncle Cyril could do just as well using a catapult and marbles for shot… Love the science though.


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