Riflescope primer (Added new info and drawing 6/16/2020)

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March 06, 2017, 10:28 AM
Riflescope primer (Added new info and drawing 6/16/2020)
Originally posted by sigfreund:
I believe a case can be made in some situations for mounting a scope as low and as close to the bore as possible.

I have a niche application where I like the sights to be as close to the bore as possible.

I favor my CZ 452 with iron sights for squirrel hunting. The sights sit lower in relation to the bore than any other arrangement that I am aware of. And the stock is designed to give a comfortable cheek weld with those iron sights.

If you have a scoped 22 rifle, zeroed at say 25, 33, or perhaps 50 yards, and a squirrel pops out on a tree 5 yards away, unless you remember to hold over, you are probably going to miss. Because the bullet hasn't had a chance to intersect the plane of the optic.

Oh course, Nikon is focusing more on longer range applications in this discussion. I like the higher sight plane of typical AR-15 optics for practical rifle use. I haven't delved into any kind of true long range shooting or competition, but I find this topic fascinating.

Buying a good quality optic will forever ruin you for cheap scopes. And you will find yourself gladly selling off a few guns to put better glass on the rifles that you really like shooting.
March 06, 2017, 10:51 AM
Originally posted by IndianaBoy:


Buying a good quality optic will forever ruin you for cheap scopes. And you will find yourself gladly selling off a few guns to put better glass on the rifles that you really like shooting.



1 Sam. 15:28
March 06, 2017, 11:02 AM
Originally posted by heathtx:
A very informative read, thank you NikonUser!

As to some of the other discussions about use/suitability/budget......

Sarcasm on......
Is the scope that came with my Rem 700 package enough to shoot 1,000 yards with? I got it for a steal, $575 at Dicks!
Sarcasm off......

Thank you for the kind words. Let me answer your sarcastic question. (Big grin on my face.)

I'm not sure what scope you have/had/will have/shoulda had on your Rem 700, but consider this. When I first started in F-TR over 10 years ago (11 to be exact,) I was coming off a longish spell of Service Rifle and I knew *a lot* about AR-15s and .223/5.56 match ammo. So I based my first F-TR rifle on an AR-15 with a 26 inch Krieger barrel, shooting 75 Amax and then 80JLKs. I did not want to spend loads of money on yet another rifle discipline, so I used a scope I had on hand at the beginning. This was a Nikon Tactical 2.5-10X44; a phenomenal scope in its own right, totally inadequate for 1000yard F-class targets with its low power and thick Mildot reticle.

So, I decided to try a Weaver T-36 a fixed power 36X40 with thin crosshairs & target dot. That scope was $380 or some such and I had to use a canted rail. But it worked just fine. It was good enough for me to make Sharpshooter at LR and HM at MR, and I won 3rd place at TSRA long range in 2000-something.

The scope had enough magnification to allow me to place my shots surgically and it was clear enough to identify these areas, after a fashion. However the scope was dark most of the time and really dark on cloudy days and early mornings in winter. In the summertime, the scope was overwhelmed by mirage. I remember shooting at 1000 yards and just watching in amazement as the aiming black on the target acted like a crazed amoeba on crack. As you might have guessed the glass was less than stellar, so mirage was amplified.

When I decided it was time to build a real F-TR rifle, I also selected another scope, this time the very popular (at that time) NF NXS 12-42X56. I never saw the crazed amoeba again, but I did see a nervous one every once in a while. When I decided it was time to upgrade the NXS with something that had ED glass, I selected the March-X 5-50X56 and this caused the amoeba to relax completely and the aiming black has never bounced again. I still want my spotting scope to show me the level of nervousness in the amoeba, not my riflescope.

So, as long as you can zero the scope at 1000 yards (using a canted rail if need be,) and the reticle retains its setting, and that the scope adjustments are reliable and true, there's no reason you can't shoot 1000 yards reliably. Whether you will do well in competition will also be influenced by other factors such as rifle, ammo, and yes, you the shooter.
March 08, 2017, 03:25 PM
The Spotting Scope.

The spotting scope is in many ways simpler than a riflescope and will produce a much better image to the eye, all things being equal. There are several reasons for that, let’s look at them.

A spotting scope’s objective (front lens) is not limited in size by having to sit on a rifle. That means it can be as big as you’re willing to carry and we all know now that bigger lenses let through more light than smaller lenses. Look for objectives in the 60 to 100mm range in diameter and compare that to riflescope objectives in the 30-50mm range. My two largest riflescopes have 56mm lenses and I have heard of a Zeiss Victory riflescope with a 72mm objective, for nighttime hunting, but I don’t think it’s available anymore.

The tube if the spotting scope is quite simple and doesn’t need to be restricted to small sizes line 1inch or 30mm, it can thus handle bigger lenses (more light going through them). The spotting scope uses a pair of Porro prisms to invert the image from the objective so that it looks right side up and proper to your eye. Between the objective lens and the first Porro prism, there is a focusing lens which is moved by the internal focusing wheel on the spotting scope (think side focus on a riflescope.) The image from the second Porro prism is what the eyepiece focuses on. If you have an angled spotting scope there is an additions Porro prism to get the image set to 45 degrees for the eyepiece.

Notice the absence of an inner tube and reticle and adjustment knobs and so on. A spotting scope is simpler, but can be more expensive than a riflescope because of the larger glass used. The eyepiece is where all the zooming takes place and the design of the eyepiece determines the eye relief available. For my Kowa, the fixed power eyepieces are cheaper than the zoom one.

Some spotting scopes have interchangeable eyepieces. I know mine does and that’s an important feature for me. In such cases, you MUST factor in the price of the spotting scope body AND an eyepiece in your buying decision. Eyepieces can be quite expensive, so treat them with respect and never touch the lenses or the prism in the scope body.

As with riflescope and camera lenses, coatings are critical to the performance of a spotting scope and remember, quality of the glass is important there also. If you spend a lot of time looking through a spotting scope, you will appreciate the better glass. But if all you need is to look at the shots on a paper target, then it’s different.

I have a filter on my spotting scope because I have had one scope take a nose dive, objective lens first, into rocks when the tripod tipped over. My heart stopped (well skipped a beat) when I saw that. When I picked up the Nikon Earth and Sky from the ground, there was not a scratch on the objective lens. Unbelievable. I’m not taking any more chances however, and my Kowa as a filter on it. I also have a circular polarized filter for it, but I don’t use that for shooting purposes, only for pictures. And that’s another thing; some spotting scopes have attachments that will let you connect a DSLR or other camera types. You may want to keep that in mind during your purchase selection process if you intend to use your spotting scope for more than just shooting. My Kowa makes a great telescope for looking at the Moon and other things. My DSLR attaches to it very nicely and that’s excellent also.

Let’s talk tripod for a minute. I use my spotting scope on the line with me when I shoot in competition. I also use my spotting scope to score and to sometimes take pictures or videos during a competition. Instead of having 2 or more spotting scopes or multiple tripods/mounts, I have a single tripod that can collapse all the way to the ground with its middle column pulled out and extended to the side. It’s a Manfrotto tripod made of carbon fiber and the head is made of magnesium, all in an effort to minimize weight. I’ve tried multiple heads and finally settled on a pistol grip style that makes it very easy to maneuver when lying prone alongside the rifle and yet stays exactly where you have it set when you release the grip. I can collapse the scope for prone in a few seconds or set it up for scoring from a sitting position or picture/video/motoring from a standing position in a jiffy.
March 09, 2017, 05:17 PM
Further thoughts on the Zoom range
I've had occasion to discuss further about zoom range for a riflescope and its effect on the image that comes to your eye and I thought I would update this thread with that.

As I said originally, the standard zoom range is 3X with lots of offerings in the 4X range. There are also 5X and 6X and my March-X has a 10X zoom. When you see such a range you have to ask yourself, why isn't it higher and why are manufacturers so slow to move to 4X or higher? Another question is why are higher zoom factors only available on pricey optics?

Those are great questions (I know, because I asked them.) Back to the internals. The objective lens creates a picture of the objective at the first focal point; the one in front of the erector cell. If you have an AO, you twist the objective to focus it, if you have a side-focus you twist the left-hand knob and that moves the focusing lens inside the scope between the objective and that first focal plane to focus. Now that first plane is the one that will be inspected by the rest of the riflescope. This image will have a certain diameter, which will be smaller than the objective lens and the main tube. We can calculate this field-of-view but essentially that's what have to work with. This image will go through the erector cell to invert it for proper appearance in the eyepiece and that image will be focused on the second focal plane in front of the zoom lenses. Now at this point, we only have the FOV to match the size of the inner tube and that's smaller than the FOV of the first focal plane. We are only getting a portion of the whole image coming into the riflescope.

This image is the one that will magnified by the zoom lenses. Now remember that the formula for the size of the eye relief is objective lens diameter in mm divided by the magnification. The reason it drops off with magnification is that we are only using a certain portion of the light let in by the objective lens. Less area to look at means less light. But there's another issue besides brightness, it's resolution. As the zoom increases we are looking at a smaller and smaller portion of the image projected by the objective lens. And this is where the quality of the glass comes in. If the image projected by the objective and inverted by the erector cell goes through lower quality glass, it will degrade and suffer. If you have a flat screen display on your computer, get close to it and then use a magnifying glass on the image. The panels with high resolution will take longer to show a bad picture compare to lower resolution displays. This is analogous to what happens with the glass lenses and the higher the zoom factor, the more this becomes a problem. So you must have excellent glass to be able to support 5, 6 and 10X zoom without degrading the image to the point you can detect it.

We said before bigger glass transmits more light, it also presents a bigger, higher resolution image. So if you are looking at higher zoom ratios, you have to factor in the better glass (and higher cost,) that's one of those pesky trade-offs.
March 14, 2017, 01:37 PM
Looking at the future of riflescopes

I thought I would deviate a little bit on this thread and talk about what the future may hold in sport optics, notably riflescopes and spotting scopes. The following are just guesses of mine gleaned from what is taking place in photography circles. I have no direct or indirect lines to any manufacturer or labs, these are my guesses.

We are going to see advancements in zoom ranges and reticles, and coatings and adjustment knobs and so on, but it will be incremental. I believe the next big step is going to be the addition of electronics in the scope, building on what the camera world has been doing for years now in DSLR and more recently in mirrorless cameras. We have already seen scopes with built-in laser rangefinders, but I think we are going to see something more dramatic soon.

A DSLR works virtually the same way a film SLR works except that instead of film, there is a CCD sensor grid that is exposed to the image when the shutter opens. This CCD (Charge-Coupled Device) is composed of Pixels (Picture Elements) arranged in rows and columns to form a raster image. This is just like your flat panel display, except much smaller and it detects light rather than emitting it. Currently in Photography, there are several standard sizes of these CCD sensors. The biggest common one is the full-frame 35mm sensor, the same size as the common 35mm film; 36mmX24mm. Going smaller from there you have the APS-C sizes for Nikon DX (24mmX16mm) with 6000 X 4000 pixels (24MP) and other smaller ones such as Four Thirds and 2/3” and so on, going smaller still. (I’m talking Nikon cameras here, because those are the ones I know best, but Canon is very similar, almost identical in many ways.)

Contrary to what you might think, the size of the sensor does not dictate the number of pixels. For example, the Full Frame sensors or FX cameras from Nikon have something like 20MPs, whereas the DX cameras have 24 or more MPs. There are also FX cameras with 36MPs, but the top of the line is still an FX at 20MPs. The size of the pixel plays a role in the quality of the picture especially when you get into higher ISO ratings, more on this later. However for normal daylight conditions, smaller pixels do fine until you get extreme.

The big difference between a camera and a riflescope is that in a camera, the lenses magnify the image onto the sensor or the film and think of the sensor as being in the first focal plane, with the picture inverted (upside down and left to right.) All the magnification of the image is done in front of the sensor. In a riflescope, most of the magnification is done after the first focal plane. The image in the eyepiece is generated by a magnifying lens looking at that picture in the first focal plane.

A byproduct of a smaller pixel and smaller sensor is what is commonly referred to as a crop factor or focal length multiplier. What this means is that the same size lens will be have a higher focal length for a smaller sensor. For example, on a 35mm film camera or a FF sensor, the standard lens, one that does not produce any magnification, in other words 1X, is about 50mm. For a DX camera, the standard lens is about 35mm. The number we usually work with for crop factor is 1.53 or so. So a 50mm lens on a DX sensor will be the equivalent of a 75 or 80mm lens on a 35mm film camera. So having the smaller sensor increases the magnification of a specific focal lens optic. In photography the problem arises when using wide-angle lenses but for us shooters, that issue does not exist, we want magnification.

Let’s talk resolution now. With the DX-size sensor we have an image that that is composed of 24 million pixels (6000X4000). This is what we have to work with behind the sensor, if you will. On my 55 inch 4K display (3840X2160 pixels), I can’t even project the JPEG image at its full size. The 43inch wide screen has a resolution of 89 PPI (Pixels Per Inch, and you have to get very close to start detecting the rows and columns. This allows me to zoom in on an area of the image quite drastically and still get an excellent image.

Let’s translate that to a riflescope. The first thing that would disappear is the erector set. We no longer need this assembly to swap reverse the image for viewing, everything would be done by the CPU. The optics would be separated now with two sets. The first one would be up front and act like a camera lens, working to bring a magnified image to the CCD sensor in the first focal plane. They will also be subject to the same limitations as camera lenses for the size of the sensor in use. So, don’t expect more than 4-10X depending on the sensor size. The bigger the sensor, the smaller the magnification in front of it. This is where we will focus the image, just like we do in a camera lens. We can even have autofocus.

Once the sensor gets the image, it will start presenting it to the eyepiece and this is where the magic will begin, because we can get things done to this image. Essentially what we will have is a small screen presented to our eye, with perhaps a lens (the second set of lenses) in front of our eye to adjust the diopter to accommodate different vision level. The zooming in and the reticle projection can all be done by the CPU and this would eliminate the need for the inner tube.

We can also have such features as VR (vibration reduction,) and correction to reduce or eliminate mirage. Earlier I mentioned ISO number, this is a measure of the sensitivity of the sensor (think film speed, AS25, ASA400, etc.) The higher the number, the more sensitive the sensor is and that’s adjustable in the camera. I am able to take pictures indoors without a flash and still get proper exposure. In an electronic riflescope, we would have the same capability, so the amount of light entering the scope can actually be boosted internally.

I also talked about Mirrorless cameras. This is a camera that does not have an optical viewfinder, the image presented for talking the picture is taken directly from the CCD sensor. This is essentially what this riflescope would be, a mirrorless camera fitted out in a riflescope and built to take recoil.

The limitations would be with the power consumption of such a device. It will need batteries but the technology has come a long way. It could be built to have the system go on standby if it does not detect an eye looking through it.

If it uses industry-standard sensors, the electronic riflescope of the future will not present a round image, it will be rectangular, like the sensor. Of course, the CPU can present any image it wants so it can still be round, but we will lose field of view. Also, adjustment range limitations will be huge compared to what we have now. Goodbye 20MOA ramps.

Once this format is reality, the possibilities are endless. We can record shots or scenes, we can have as many reticle types as we want, illuminated or other. We can have Bluetooth communication to other devices, endless I tell you.

As for price; the first ones will be pricey but as with cameras, these prices will rapidly come down. We will see continual improvements in CPU, sensor, software and features, it will be very different from what we see now.

For spotting scopes, this can get even better with FF sensors and onboard CPUs with more capabilities.

The days of lenses only are numbered.

This message has been edited. Last edited by: NikonUser,
March 14, 2017, 03:55 PM
Very interesting series, thank you very much. I really just started using a scope on a rifle about 10 years ago when I started prairie dog shooting. Wish this article (to explain the technical stuff to a novice) had been around then because I would not have a drawer full of old scopes like holsters looking for the right one. I shoot in South Dakota and the most serious problem for long range shots (500-1200yds) is the heat waves obscuring the targets on higher magnifications. Are there any filters/coatings that can be used to cut down on this problem other than just dialing down the magnification. I look forward to hearing more of your thoughts.

Freedom comes from the will of man. In America it is guaranteed by the 2nd Amendment
March 14, 2017, 04:52 PM
That's a very good question low8option. In fact, I have played around with some filters and what I have found is that with a yellow filter, I seem to detect more of the mirage (the heat waves that you mention, in competition circles we call it mirage, incorrectly.)

I have not tried with other colors or a polarizer but my thinking is that it's really just due to the fact I'm introducing about 1/3 to 1/2 more EV with the filter (darker will bring in more) and that has the effect of extending the Depth-Of-Field and bringing in even more mirage over a greater distance.

In my estimation, the best way to cut down the mirage in the riflescope is to get a larger objective and better glass. When I look through my March-X even at 40X, I do not detect the mirage anywhere near as well as I could with my NF NXS 12-42X56. My March-X has ED glass which I believe helps cut down the mirage.

I don't believe there is anything you can do to minimize mirage for a given scope, but there are ways to increase the mirage.

So look for bigger objective to reduce the depth of field and for better glass, especially something with ED glass. No guarantees here, just some observations.

As I explained here earlier and in other posts, I want to see the mirage in my spotting scope, (it's a high quality, but non-ED glass and I have a polarizer lens for it,) but I want to reduce or eliminate the mirage in my riflescope, (March-X 5-50X56 with ED glass.)
March 15, 2017, 10:01 AM
Well, it seems my vision of the future of riflescopes is a little too late. On another board, I was informed about this scope.

I don't feel too bad that I'm late to the game, but I seem to have called it pretty well. The sensor they use is about half the size of the DX sensor I talked about and that kind of limits the display and the zoom range, but it's a great start into the future. Now, I think I want one of these.

ETA: I believe this riflescope uses something like the CX sensor format AKA 1", used by Nikon and Sony. It goes up to 18MP which should produce quite a good image. I'm thinking the next limitation is the mini-display resolution.

This message has been edited. Last edited by: NikonUser,
March 15, 2017, 11:16 AM
Originally posted by NikonUser:
Well, it seems my vision of the future of riflescopes is a little too late.

Something else to feed with batteries.
When the pock o’ lips comes, there’s going to be a lot of sad folks is all I can say.

Thanks for that informative discussion about the future of electro-optical devices, NikonUser.

“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
— Bertrand Russell
March 15, 2017, 11:37 AM
That's why BUIS exist in the first place, but I get what you're saying. It's like the folks who buy lots of frozen foods prior to a hurricane.
March 21, 2017, 02:40 PM
I wanted to add some more empirical data in support of my hypothesis about ED glass and mirage.

This past weekend I shot a 600 yard match and the mirage was very pronounced. People were commenting about it, and a bunch of them dialed back on their scope magnification. I increased the magnification from my usual 40X to the full 50X available from my March-X 5-50X56. While shooting, I used my Kowa spotting scope TSN-82SV 80mm objective with the 27X eyepiece to read the conditions. This time the mirage was the leading indicator for all switches and I barely looked at the flags. I was on my Kowa all the time, watching the huge mirage river going to and fro. The mirage was so clear and evident in the Kowa; when I detected the condition I wanted or could figure out the hold, I would quickly transition to my rifle and at 50X, I could barely detect any mirage in that scope. This allowed me to place the shots very surgically and it was actually a lot of fun.

Now, the Kowa does not have ED glass, but its glass is still excellent. I do know that at 27X, I had a lot more depth of field and was probably picking up more mirage, but that's exactly what I want in a spotting scope. On the other hand, my March riflescope does have ED glass and cranking up to 50X further cut down the depth of field further cut down on the mirage. I was astounded at the difference looking in the two eyepieces.
March 30, 2017, 06:17 AM
Just read through the thread again. Great information. Thanks for taking the time to do it.
March 30, 2017, 03:46 PM
Originally posted by NikonUser:
Well, it seems my vision of the future of riflescopes is a little too late. On another board, I was informed about this scope.

That is a very attractive price for that level of technology. I have to wonder how durable it actually is. The fact that it runs on AA batteties is a huge plus.

But back to the subject matter. Who is still building scopes with heavy duty internals that allow reliably repeatable adjustments?

'I'm pretty fly for a white guy'.

March 31, 2017, 11:09 AM
Heavy duty, repeatable adjustments? Well, actually there's more to it than that.

When it comes to adjustments, the principle of operation here is a pair of screws one at 12 o'clock and another one at 3 o'clock. these screws push the inner tube down (12 o'clock screw) and to the left (3 o'clock screw.) At the 6 o'clock and 9 o'clock position, there is a spring of some type that pushes the inner tube to the top (6 o'clock spring) and to the right (9 o'clock spring).

The pitch of the screw will dictate how much the inner tube is displaced by each turn of the screw. In the old days, your adjustment was done using a quarter that would allow you to turn the screw one way or the other but it had no measurement, it was a continuous screw; no clicks. If you wanted the bullet to go up you needed to make the scope look down the objective, and since the image in the first real focal plane was inverted and upside down your inner tube had to go up. It still does, by the way. Of course, it was the same for the windage adjustment so if your bullet needed to go left, the inner tube had to left (inverted image, remember.)

The distances involved are incredibly small, as you can expect, so the pitch of the screw is very tight. At some point the scope manufacturers started producing adjustments that measurements that allowed you to actually measure the displacement of the bullet for a certain amount of screw turning. At this time, there are three popular angular displacement measures. By angular displacement, I mean that the displacement will be a value for an angle since everything is relative to the distance from the scope to the target; as the distance doubles, so will the physical displacement on the target for a specific angle.

The three popular measures are MOA (Minute Of Arc (or angle): 360 degrees in a circle, 60 minutes per degree or 21,600 MOA per circleWink Milliradian (defined as one thousandth of a radian, 6400 or 6000 Mil per circle, depending on type) and IPHY (Inch Per Hundred Yards) You could also add a fourth unit, call it the "anything goes," and that would apply to scopes that do not have measures of adjustment.

Each unit has their proponents but most everyone agrees that having units of measure that are the same for the reticle and the adjustment knobs is "a good thing (tm)."

Let's just take MOA, because that's the one with which I'm most familiar. The adjustment knobs for any of the units, come in essentially two flavors; so-called 'target knobs', and covered knobs. The former are usually bigger units with all manners of markings on them and some type of texture on the knob to make it easy to grasp with two fingers and twist. The other type is hidden under a cover and is usually much more simplistic. With this type you have to twist off the cover, do your adjustment and then put back the cover and never play with it again; these knobs are essentially used to zero the rifle at a certain distance with a certain load and then you lock that setting down and you hold off from there with the reticle or some other means.

The target knobs are meant to be twiddled and played with and those are the ones that are more interesting in this discussion. What we want from these knobs is repeatability, predictability and longevity.

Repeatability is the quality which enables you to trust that when you dial for one distance and then dial back to where you were, the scope's inner tube will be pointed where it was.

Predictability is the quality of the inner tube to move exactly the distance you expect it to move with a set number of units displacement, through its entire range. It's tied to repeatability, but it's not the same. I have seen scopes move back to the proper initial setting but when I wanted 2.75 MOA displacement, I was getting something else, not quite it.

The final one is longevity. This is the quality of the springs and knobs to function properly through large repeated changes, year after year. Some scopes start losing their repeatability and predictability after a time.

Those qualities are treasured by knob twisters like myself and a scope that lacks in any of there areas is soon replaced. As one would expect, these qualities are a function of price and indeed, I am not aware of any systemic failures with the top brands in that area. When the price is reduced, these qualities may suffer but there are exceptions to that rule. For instance, the Micro-Trac system of the Weaver scopes is astounding for that price.

I have Nightforces, March, Nikon and Leupold scopes as well as a pair of Weavers and they've all given me good service. I have a few lesser scopes and the less said about them the better.

If you want to check your scope for these qualities, I would suggest you perform a box test; Shoot a group at the initial setting, then move 4 units to the right and shoot another group, then move 4 units up and shoot another group and then 4 units left and shoot another group and finally move 4 unit down and shoot another group and that last group should be on top of the initial group. The other groups should be at the offset predicted by the displacements you have done to the scope, group by group.

One important feature for competition shooters is being able to zero at the distance required and then being able to dial to the other distances by counting the revs or the clicks or a combination of the two. Also, some scopes offer a zero stop feature which allows you to return to a known setting in case you get lost in the revolutions. Some scopes have a number of units per revolution that makes big changes easy; 10 units per ref or 5 unit per rev, while others are more goofy like 7 or 9 units per rev. Once you're used to your scope, that issue goes away.

This message has been edited. Last edited by: NikonUser,
March 31, 2017, 06:41 PM
Originally posted by NikonUser:
Milliradian (defined as one thousandth of a radian, 6400 or 6000 Mil per circle, depending on type)

Not to detract from the rest of your (as usual) excellent informative discussion, but although 6400 mils per circle is one common figure, 6000 mils per circle is not the second. The true and more or less exact value is that there are 6283.185 mils per circle (2000 × π) (if you have trouble with the displayed font, π is the value of pi, or 3.1416…). The 6400 figure is used by the US military and I believe NATO in general because it’s close enough to the actual value and it’s far easier to perform calculations with (or was before the development of electronic calculators). According to Wikipedia the Warsaw Pact countries did use the 6000 figure and Sweden uses 6300 for mils per circle.

As I understand it, current scope sights whose adjustments are in mils use the true (2000π) value. The International System of Units (metric system, or SI) speakers among us enjoy the advantage of the fact that a 1 mil angle subtends 1 meter at a distance of 1 kilometer, or 0.1 mil subtends 1 centimeter at 100 meters. If our ranges were laid out in meters and our targets were printed with centimeter grids, it would be very easy to use a scope with windage and elevation adjustments in 1/10 mil increments.

“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
— Bertrand Russell
March 31, 2017, 07:56 PM
I was hoping someone would pipe in on milliradian stuff because, while I know how it works and I have a Mildot master somewhere, I am not comfortable using it. And that's simply because I'm old and so deep into MOA stuff. I never use Mils. I think we read the same Wiki because that's where I got the 6000 figure. I just thought NATO would be used in this country and there are far more WP countries and equipment than whatever Sweden would have produced.

So thanks for the correction and further info.

And as I like to say, there are two types of countries in the world; those who use the metric system and those who have sent men to the Moon and returned them home.
April 01, 2017, 07:55 AM
Originally posted by SgtGold:
Who is still building scopes with heavy duty internals that allow reliably repeatable adjustments?

There are many options. Most of the higher end tactical-type scopes seem to track flawlessly year after year.

My time in tactical/steel matches isn't all that extensive, but I have seen the vertical tracking function of a number of scopes fail in competitions and training. IMO, this is the #1 reason scopes fail in such matches -- we are constantly dialing up and down elevations.

The brands that failed include Burris, Leupold, Nikon, Schmidt & Bender, Athlon, and US Optics. I've never seen a Vortex fail, however one such failure was reported on this site last year. I haven't seen or heard of a Nightforce's tracking fail. My own NF scopes have tracked flawlessly -- NXS (SFP, FFP, and Compact), ATACR, and SHV.

Are a few failures here and there indicative of a company's entire line of scopes? I don't know. I'll let others weigh in.
April 01, 2017, 08:09 AM
Originally posted by NikonUser:
there are far more WP countries

Not any more. Wink

You make a good point though, and until I read the same Wiki article I had never heard of the 6000 figure. As a point of trivia it would be interesting to know what is now used by the former Warsaw Pact countries that have since joined NATO (all, I believe, except Russia). Were they required to switch to the 6400 standard for commonality? I also wonder about other major countries like China or even Russia now.

“The fundamental cause of trouble in the world today is that the stupid are cocksure while the intelligent are full of doubt.”
— Bertrand Russell
April 01, 2017, 10:19 AM
Originally posted by fritz:

There are many options. Most of the higher end tactical-type scopes seem to track flawlessly year after year.

My time in tactical/steel matches isn't all that extensive, but I have seen the vertical tracking function of a number of scopes fail in competitions and training. IMO, this is the #1 reason scopes fail in such matches -- we are constantly dialing up and down elevations.

The brands that failed include Burris, Leupold, Nikon, Schmidt & Bender, Athlon, and US Optics. I've never seen a Vortex fail, however one such failure was reported on this site last year. I haven't seen or heard of a Nightforce's tracking fail. My own NF scopes have tracked flawlessly -- NXS (SFP, FFP, and Compact), ATACR, and SHV.

Are a few failures here and there indicative of a company's entire line of scopes? I don't know. I'll let others weigh in.

A few years back (5?) we had reports of 3 NF NXS12-42 failing in one weekend at TSRA mid-range. As fritz says, they all lost their elevation and I can see that at that time as lots of folks use the same rifle for LR and MR and stepping down for 1000 yards to 300 and then up to 500 and the 600, that's a lot of winding. I still bought my NXS the following month, but I was nervous for a while. It's never failed me, nor have any of my other higher priced scopes.

On the other hand, I have never heard of a Weaver T-series with Micro-Trac ever having issues with tracking and I abused the snot out of mine. It's too bad the glass on the Weaver is so poor. In summer time, the mirage is so bad you think the aiming black is an amoeba on crack and speed (or whatever drugs make people go crazy and erratic.) The NXS glass was much better and the mirage was much tamer and the March is just a dream shooting in mirage.