A good riflescope is essential for many types of competition, and the vast majority of hunters have scoped rifles. Some F-Class and benchrest competitors are now using optics with up to 60X magnification. Over the past 30 years, scopes have continued to evolve with improved glass, more reticle types, vastly increased elevation travel, bigger main tubes, FFP and SFP options, and even built-in electronics.
When shopping for a riflescope, it’s useful to understand how scopes work — how the internal mechanisms control windage and elevation, how parallax controls work, and how magnification levels are controlled.
Basics of How Riflescopes Work
This Burris video (above) covers the key aspects of scope function: zoom magnification, windage control, elevation control, parallax control (front or side mount), and ocular lens focus. There are some tips on getting a new scope running smoothly — it’s wise to rotate the power control a few times as well as both windage and elevation knobs. The video below also explains how to set ocular focus controls optimally.
Scope Break-In Methods and Diagnosing Issues — Great Video
We recommend that all serious shooters watch this video start to finish. A very knowledgeable scope engineer, Leupold’s Mike Baccellieri, explains the fine details of scope operation — with very useful recommendations on how to ready a new scope for use (See 36:50 time-mark). With a new optic he advises to run the controls multiple times to full travel. Also, take your time to get the diopter control just right (See 26:40 time-mark).
The video also explains why, with a new scope or one that hasn’t been used much, it is sometimes effective to rotate the elevation PAST the desired setting then come back a click (See 35:40 time-mark). In addition, near the end of the video, the expert explains how you can use a mirror to determine if the scope mount (base and/or rings) is NOT aligned with the bore axis, forcing excess travel to get on target (See 42:00 time-mark). We have seen this caused by scope rails attached slightly off axis.
Large diameter turrets make windage and elevation markings easier to see, and the click “feel” may be more noticeable given the greater diametrical travel between clicks.
First Focal Plane (FFP) vs. Second Focal Plane (SFP)
The main visual difference between First Focal Plane (FFP) and Second Focal Plane (SFP) scopes is the appearance of the reticle (and its hash marks) at different magnification levels. With a FFP scope, the reticle increases in visible size (and line thickness) with increased magnification. This is so the angular hash marks remain constant (in Mils or MOA angular span) at all magnification levels. So, on a 10-30X FFP scope, a 0.1 Mil hash mark represents the SAME angular measurement at 10X, 20X, or 30X (or any magnification). The downside of the FFP system is that the reticle lines can appear very thick at high magnification. But for a PRS/NRL match, with targets at multiple distances, it is important that the hash marks represent the same angular measurement at all power settings.
On a Second Focal Plane (SFP) scope, by contrast, the reticle lines (and hash marks) appear visually (in thickness) the same at all magnification levels. This means the hash mark divisions will only be precise at one magnification level, as designed by the manufacturer. For example, you could have exact 1 MOA Hash marks at 10X. But zoom the scope to 20X and the same reticle hash mark would then cover 2 MOA. SFP scopes are popular with competition shooters who shoot at specific known distances. Not having thick reticle lines at 25X to 50X is an advantage when aiming at precise benchrest and F-Class targets.
ZEISS now makes excellent FFP Scopes with both MOA and Milrad options
Minute of Angle (MOA) vs. Milliradian (MILRAD or MIL)
This video also explains MOA vs. MRAD (Milliradian) controls. A Minute of Angle (MOA) is an angular measurement that represents 1.047″ at 100 yards. Modern MOA scopes are typically configured with 1/4 MOA or 1/8 MOA clicks. A Milliradian (MRAD) is another angular measurement defined as one-thousandth of a radian. Milrad scopes are commonly configured with 0.1 Milrad clicks. How much is a 0.1 mil at 100 yards? One mil equals 3.6 inches at 100 yards; therefore, 1/10th of that, 0.1 Mil, equals 0.36” – roughly a third of an inch – at 100 yards. That’s pretty close to the common quarter-inch (1/4 MOA) increment found on MOA riflescopes.
Sightron makes excellent high-magnification SFP zoom scopes favored by many competitors. These have proven quite reliable and offer very good performance for the price.
Scope Mounting Method and Alignment
When mounting a scope, you want to make sure the scope is aligned properly, so that vertical travel is precisely up and down, not offset. Begin by supporting the rifle with a good front and rear rest. Use a portable level to ensure the rifle is not tilting slightly left or right around the barrel bore axis. Then you want to align your scope’s vertical axis. For this, we recommend setting up a plumb bob — a weighted line that hangs straight down. This can be set up indoors or outdoors. Align your reticle’s vertical axis precisely with the plumb bob line, making sure not to move the rifle.
One caution — we have seen some riflescopes that are internally off-axis by up to 4 degrees. In this case, you can align the reticle’s vertical axis with the plumb bob line but then find that your turrets are slightly titled. That is a scope manufacturing fault that will result in some error when you input a large click value (e.g. 10+ MOA up or down).
When mounting your scope, another key factor to consider is the eye relief — the distance of the rear “ocular” lens to your eye. When mounting the scope, put your head in the position at which you normally shoot. NOTE: As your optimal head position may be quite a bit different when shooting prone vs. shooting from a bench, you may want to adjust the scope placement for different shooting positions. This Editor had to move his comp rifle scope about an inch rearward when local club matches changed from prone to bench.
Video collection suggested by Boyd Allen
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In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.
How many degrees of muzzle elevation do you think it would take to hit a barn at 3000 yards? Ten Degrees? Twenty Degrees? Actually the answer is much less — for a typical hunting cartridge, five to seven degrees of up-angle on the rifle is enough to create a trajectory that will have your bullet impacting at 3000 yards — that’s 1.7 miles away!
Five degrees isn’t much at all. Look at the diagram above. The angle actually displayed for the up-tilted rifle is a true 5.07 degrees (above horizontal). Using JBM Ballistics, we calculated 5.07° as the angle that would produce a 3000-yard impact with a 185gr .30-caliber bullet launched at 2850 fps MV. That would be a moderate “book load” for a .300 Win Mag deer rifle.
Here’s how we derived the angle value. Using Litz-derived BCs for a 185gr Berger Hunting VLD launched at 2850 fps, the drop at 3000 yards is 304.1 MOA (Minutes of Angle), assuming a 100-yard zero. This was calculated using a G7 BC with the JBM Ballistics Program. There are 60 MOA for each 1 degree of Angle. Thus, 304.1 MOA equals 5.068 degrees. So, that means that if you tilt up your muzzle just slightly over five degrees, your 185gr bullet (2850 fps MV) will impact 3000 yards down-range.
Figuring Trajectories with Different Bullets and MVs
If the bullet travels slower, or if you shoot a bullet with a lower BC, the angle elevation required for a 3000-yard impact goes up, but the principle is the same. Let’s say you have a 168gr HPBT MatchKing launched at 2750 fps MV from a .308 Winchester. (That’s a typical tactical load.) With a 100-yard zero, the total drop is 440.1 MOA, or 7.335 degrees. That’s more up-tilt than our example above, but seven degrees is still not that much, when you consider how a rifle might be handled during a negligent discharge.
Think about a hunter getting into position for a shot. If careless, he could easily touch off the trigger with a muzzle up-angle of 10 degrees or more. Even when shooting from the bench, there is the possibility of discharging a rifle before the gun is leveled, sending the shot over the berm and, potentially, thousands of yards down-range.
Hopefully this article has shown folks that a very small amount of barrel elevation can make a huge difference in your bullet’s trajectory, and where it eventually lands. Nobody wants to put holes in a distant neighbor’s house, or worse yet, have the shot cause injury. Let’s go back to our original example of a 185gr bullet with a MV of 2850 fps. According to JBM, this projectile will still be traveling 687 fps at 3000 yards, with 193.7 ft/lbs of retained energy at that distance. That’s more than enough energy to be deadly.
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Let’s say you’ve purchased a new scope, and the spec-sheet indicates it is calibrated for quarter-MOA clicks. One MOA is 1.047″ inches at 100 yards, so you figure that’s how far your point of impact (POI) will move with four clicks. Well, unfortunately, you may be wrong. You can’t necessarily rely on what the manufacturer says. Production tolerances being what they are, you should test your scope to determine how much movement it actually delivers with each click of the turret. It may move a quarter-MOA, or maybe a quarter-inch, or maybe something else entirely. (Likewise scopes advertised as having 1/8-MOA clicks may deliver more or less than 1 actual MOA for 8 clicks.)
Reader Lindy explains how to check your clicks: “First, make sure the rifle is not loaded. Take a 40″ or longer carpenter’s ruler, and put a very visible mark (such as the center of an orange Shoot’N’C dot), at 37.7 inches. (On mine, I placed two dots side by side every 5 inches, so I could quickly count the dots.) Mount the ruler vertically (zero at top) exactly 100 yards away, carefully measured.
Place the rifle in a good hold on sandbags or other rest. With your hundred-yard zero on the rifle, using max magnification, carefully aim your center crosshairs at the top of the ruler (zero end-point). Have an assistant crank on 36 (indicated) MOA (i.e. 144 clicks), being careful not to move the rifle. (You really do need a helper, it’s very difficult to keep the rifle motionless if you crank the knobs yourself.) With each click, the reticle will move a bit down toward the bottom of the ruler. Note where the center crosshairs rest when your helper is done clicking. If the scope is accurately calibrated, it should be right at that 37.7 inch mark. If not, record where 144 clicks puts you on the ruler, to figure out what your actual click value is. (Repeat this several times as necessary, to get a “rock-solid”, repeatable value.) You now know, for that scope, how much each click actually moves the reticle at 100 yards–and, of course, that will scale proportionally at longer distances. This optical method is better than shooting, because you don’t have the uncertainly associated with determining a group center.
Using this method, I discovered that my Leupold 6.5-20X50 M1 has click values that are calibrated in what I called ‘Shooter’s MOA’, rather than true MOA. That is to say, 4 clicks moved POI 1.000″, rather than 1.047″ (true MOA). That’s about a 5% error.
I’ve tested bunches of scopes, and lots have click values which are significantly off what the manufacturer has advertised. You can’t rely on printed specifications–each scope is different. Until you check your particular scope, you can’t be sure how much it really moves with each click.
I’ve found the true click value varies not only by manufacturer, but by model and individual unit. My Leupold 3.5-10 M3LR was dead on. So was my U.S.O. SN-3 with an H25 reticle, but other SN-3s have been off, and so is my Leupold 6.5-20X50M1. So, check ‘em all, is my policy.”
From the Expert: “…Very good and important article, especially from a ballistics point of view. If a ballistics program predicts 30 MOA of drop at 1000 yards for example, and you dial 30 MOA on your scope and hit high or low, it’s easy to begin questioning BCs, MVs, and everything else under the sun. In my experience, more than 50% of the time error in trajectory prediction at long range is actually scope adjustment error. For serious long range shooting, the test described in this article is a MUST!” — Bryan Litz, Applied Ballistics for Long-Range Shooting.
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Have you recently purchased a new scope? Then you should verify the actual click value of the turrets before you use the optic in competition (or on a long-range hunt). While a scope may have listed click values of 1/4-MOA, 1/8-MOA or 0.1 Mils, the reality may be slightly different. Many scopes have actual click values that are slightly higher or lower than the value claimed by the manufacturer. The small variance adds up when you click through a wide range of elevation.
In this video, Bryan Litz of Applied Ballistics shows how to verify your true click values using a “Tall Target Test”. The idea is to start at the bottom end of a vertical line, and then click up 30 MOA or so. Multiply the number of clicked MOA by 1.047 to get the claimed value in inches. For example, at 100 yards, 30 MOA is exactly 31.41 inches. Then measure the difference in your actual point of impact. If, for example, your point of impact is 33 inches, then you are getting more than the stated MOA with each click (assuming the target is positioned at exactly 100 yards).
How to Perform the Tall Target Test
The objective of the tall target test is to insure that your scope is giving you the proper amount of adjustment. For example, when you dial 30 MOA, are you really getting 30 MOA, or are you getting 28.5 or 31.2 MOA? The only way to be sure is to verify, don’t take it for granted! Knowing your scopes true click values insures that you can accurately apply a ballistic solution. In fact, many perceived inaccuracies of long range ballistics solutions are actually caused by the scopes not applying the intended adjustment. In order to verify your scope’s true movement and calculate a correction factor, follow the steps in the Tall Target Worksheet. This worksheet takes you thru the ‘calibration process’ including measuring true range to target and actual POI shift for a given scope adjustment. The goal is to calculate a correction factor that you can apply to a ballistic solution which accounts for the tracking error of your scope. For example, if you find your scope moves 7% more than it should, then you have to apply 7% less than the ballistic solution calls for to hit your target.
NOTE: When doing this test, don’t go for the maximum possible elevation. You don’t want to max out the elevation knob, running it to the top stop. Bryan Litz explains: “It’s good to avoid the extremes of adjustment when doing the tall target test.I don’t know how much different the clicks would be at the edges, but they’re not the same.”
Should You Perform a WIDE Target Test Too?
What about testing your windage clicks the same way, with a WIDE target test? Bryan Litz says that’s not really necessary: “The wide target test isn’t as important for a couple reasons. First, you typically don’t dial nearly as much wind as you do elevation. Second, your dialed windage is a guess to begin with; a moving average that’s different for every shot. Whereas you stand to gain a lot by nailing vertical down to the click, the same is not true of windage. If there’s a 5% error in your scope’s windage tracking, you’d never know it.”
Verifying Scope Level With Tall Target Test
Bryan says: “While setting up your Tall Target Test, you should also verify that your scope level is mounted and aligned properly. This is critical to insuring that you’ll have a long range horizontal zero when you dial on a bunch of elevation for long range shots. This is a requirement for all kinds of long range shooting. Without a properly-mounted scope level (verified on a Tall Target), you really can’t guarantee your horizontal zero at long range.”
NOTE: For ‘known-distance’ competition, this is the only mandatory part of the tall target test, since slight variations in elevation click-values are not that important once you’re centered “on target” at a known distance.
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A varmint shooter’s target is not conveniently placed at a fixed, known distance as it is for a benchrester. The varminter must repeatedly make corrections for bullet drop as he moves from closer targets to more distant targets and back again. Click HERE to read an interesting AccurateShooter Varrmint Forum discussion regarding the best method to adjust for elevation. Some shooters advocate using the scope’s elevation adjustments. Other varminters prefer to hold-over, perhaps with the assistance of vertical markers on their reticles. Still others combine both methods–holding off to a given yardage, then cranking elevation after that.
Majority View — Click Your Elevation Knob
“I zero at 100 yards — I mean really zero as in check the ballistics at 200 and 300 and adjust zero accordingly — and then set the scope zero. For each of my groundhog guns I have a click chart taped into the inside of the lid of the ammo box. Then use the knobs. That’s why they’re there. With a good scope they’re a whole lot more accurate than hold-over, with or without hash marks. This all assumes you have a good range finder and use it properly. If not, and you’re holding over you’re really just spraying and praying. Try twisting them knobs and you’ll most likely find that a 500- or 600- or 700-yard groundhog is a whole lot easier than some people think.” – Gunamonth
“I have my elevation knob calibrated in 100-yard increments out to 550. Range-find the critter, move elevation knob up…dead critter. The problem with hold-over is that it is so imprecise. It’s not repeatable because you are holding over for elevation and for wind also. Every time you change targets 50 yards, it seems as if you are starting over. As soon as I got completely away from the hold over method (I used to zero for 200), my hit ratios went way up.” — K. Candler
“When I first started p-dog shooting, I attempted to use the hold-over method with a 200-yard zero with my 6mm Rem. Any dog much past 325-350 yards was fairly safe. I started using a comeups table for all three of my p-dog rifles (.223 Rems and 6mm Rem). 450-yard hits with the .223s are fairly routine and a 650-yard dog better beware of the 6mm nowadays. An added benefit (one I didn’t think of beforehand) with the comeups table (elevation only), is that when the wind is blowing, it takes half of the variables out of the equation. I can concentrate on wind, and not have to worry about elevation. It makes things much more simple.” — Mike (Linefinder).
“I dial for elevation and hold for wind. Also use a mil-dot reticle to make the windage holds easier. For windage corrections, I watch for the bullet strike measure the distance it was “off” with the mil-dot reticle, then hold that much more the other way. Very fast once you get used to it.” — PepeLP
Minority View–Hold-Over is Better
“I try to not touch my knobs once I’m zeroed at 200 meters. Most of my varmint scopes have duplex reticles and I use the bottom post to put me on at 300 meters versus turning knobs. The reason I try to leave my knobs alone is that I have gone one complete revolution up or down [too far] many times and have missed the varmint. This has happened more than once and that is why I try not to change my knobs if at all possible.” — Chino69
“I have been using the hold over method and it works for me most of the time but the 450 yards and over shots get kinda hard. I moved to a 300 yard zero this year and it’s working well. I do want to get into the click-up method though; it seems to be more fool-proof.” — 500YardHog
Compromise View–Use Both Methods
“I use both [methods] as well — hold over out to 250, and click up past that.” — Jack (Wolf)
“I use the target knobs and crank-in elevation. I also use a rangefinder and know how far away they are before I crank in the clicks. I have a scope with drop dots from Premier Recticle and like it. No cranking [knobs] out to 600.” –Vmthtr
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Let’s say you’ve purchased a new scope, and the spec-sheet indicates it is calibrated for quarter-MOA clicks. One MOA is 1.047″ inches at 100 yards, so you figure that’s how far your point of impact (POI) will move with four clicks. Well, unfortunately, you may be wrong. You can’t necessarily rely on what the manufacturer says. Production tolerances being what they are, you should test your scope to determine how much movement it actually delivers with each click of the turret. It may move a quarter-MOA, or maybe a quarter-inch, or maybe something else entirely. (Likewise scopes advertised as having 1/8-MOA clicks may deliver more or less than 1 actual MOA for 8 clicks.)
Reader Lindy explains how to check your clicks: “First, make sure the rifle is not loaded. Take a 40″ or longer carpenter’s ruler, and put a very visible mark (such as the center of an orange Shoot’N’C dot), at 37.7 inches. (On mine, I placed two dots side by side every 5 inches, so I could quickly count the dots.) Mount the ruler vertically (zero at top) exactly 100 yards away, carefully measured.
The ability to read the wind is what separates good shooters from great shooters. If you want to learn wind-doping from one of the best, watch this video with 2010 National High Power Champion (and U.S. Army 2010 Soldier of the Year) Sherri Gallagher. Part of the USAMU’s Pro Tips Video Series, this video covers the basics of wind reading including: Determining wind direction and speed, Bracketing Wind, Reading Mirage, and Adjusting to cross-winds using both sight/scope adjustments and hold-off methods. Correctly determining wind angle is vital, Sheri explains, because a wind at a 90-degree angle has much more of an effect on bullet lateral movement than a headwind or tailwind. Wind speed, of course, is just as important as wind angle. To calculate wind speed, Sherri recommends “Wind Bracketing”: [This] is where you take the estimate of the highest possible condition and the lowest possible condition and [then] take the average of the two.”
It is also important to understand mirage. Sheri explains that “Mirage is the reflection of light through layers of air, based off the temperature of the ground. These layers … are blown by the wind, and can be monitored through a spotting scope to detect direction and speed. You can see what appears to be waves running across the range — this is mirage.” To best evaluate mirage, you need to set your spotting scope correctly. First get the target in sharp focus, then (on most scopes), Sheri advises that you turn your adjustment knob “a quarter-turn counter-clockwise. That will make the mirage your primary focus.”
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In this video, Bryan Litz of Applied Ballistics talks about Density Altitude and the effect of atmospheric conditions on bullet flight. Bryan explains why you must accurately account for Density Altitude when figuring long-range trajectories.
Bryan tells us: “One of the important elements in calculating a fire solution for long-range shooting is understanding the effect of atmospherics. Temperature, pressure, and humidity all affect the air density that the bullet’s flying through. You can combine all those effects into one number (value) called ‘Density Altitude’. That means that you just have one number to track instead of three. But, ultimately, what you are doing is that you are describing to your ballistics solver the characteristics of the atmosphere that your bullet’s flying through so that the software can make the necessary adjustments and account for it in its calculations for drop and wind drift.”
Bryan adds: “Once you get past 500 or 600 yards you really need to start paying careful attention to atmospherics and account for them in your ballistic solutions”. You can learn more about Density Altitude in Bryan’s book, Applied Ballistics for Long Range Shooting (Third Edition).
General Scientific Definition of Density Altitude
Density altitude is the altitude relative to the standard atmosphere conditions (ISA) at which the air density would be equal to the indicated air density at the place of observation. Density altitude can be calculated from atmospheric pressure and temperature (assuming dry air). Here is the formula:
Air is more dense at lower elevations primarily because of gravity: “As gravity pulls the air towards the ground, [lower] molecules are subject to the additional weight of all the molecules above. This additional weight means the air pressure is highest at sea level, and diminishes with increases in elevation”.*
Both an increase in temperature, decrease in atmospheric pressure, and, to a much lesser degree, increase in humidity will cause an increase in density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.
Leupold now offers easy online ordering for custom riflescope dials for your elevation turrets. A custom CDS dial lets you simply “dial the yardage” to have the correct elevation at distances near to far. For example, as shown below, if your target is at 550 yards, you simply dial 5.5 on the turret index. This is possible because the dial has been customized with the particular ballistics of your rifle and your load.
“Leupold engineers do all the hard work in the lab, making sure it’s easy and fast in the field,” said Rob Morrison, Leupold’s global marketing VP. “All the shooter has to do is provide us with ballistic information. From this simple data, a custom-calibrated dial is laser engraved for that specific load.”
Order Multiple Dials for Different Bullet Types
Leupolds’ custom CDS dials are tailored to the exact load used. With the ability to quickly change dials, it’s easy to set up several loads in a single rifle with a single riflescope. Transition from coyote loads to big game cartridges with a simple change of the dial. Or you can get different dials for different cartridges if you move your optic from one rifle to another. To order a CDS dial, call 1-800-LEUPOLD or visit Customshop.leupold.com/custom-dials and click on the appropriate dial for your riflescope.
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Have you recently purchased a new scope? Then you should verify the actual click value of the turrets before you use the optic in competition (or on a long-range hunt). While a scope may have listed click values of 1/4-MOA, 1/8-MOA or 0.1 Mils, the reality may be slightly different. Many scopes have actual click values that are slightly higher or lower than the value claimed by the manufacturer. The small variance adds up when you click through a wide range of elevation.
In this video, Bryan Litz of Applied Ballistics shows how to verify your true click values using a “Tall Target Test”. The idea is to start at the bottom end of a vertical line, and then click up 30 MOA or so. Multiply the number of clicked MOA by 1.047 to get the claimed value in inches. For example, at 100 yards, 30 MOA is exactly 31.41 inches. Then measure the difference in your actual point of impact. If, for example, your point of impact is 33 inches, then you are getting more than the stated MOA with each click (assuming the target is positioned at exactly 100 yards).
How to Perform the Tall Target Test
The objective of the tall target test is to insure that your scope is giving you the proper amount of adjustment. For example, when you dial 30 MOA, are you really getting 30 MOA, or are you getting 28.5 or 31.2 MOA? The only way to be sure is to verify, don’t take it for granted! Knowing your scopes true click values insures that you can accurately apply a ballistic solution. In fact, many perceived inaccuracies of long range ballistics solutions are actually caused by the scopes not applying the intended adjustment. In order to verify your scope’s true movement and calculate a correction factor, follow the steps in the Tall Target Worksheet. This worksheet takes you thru the ‘calibration process’ including measuring true range to target and actual POI shift for a given scope adjustment. The goal is to calculate a correction factor that you can apply to a ballistic solution which accounts for the tracking error of your scope. For example, if you find your scope moves 7% more than it should, then you have to apply 7% less than the ballistic solution calls for to hit your target.
NOTE: When doing this test, don’t go for the maximum possible elevation. You don’t want to max out the elevation knob, running it to the top stop. Bryan Litz explains: “It’s good to avoid the extremes of adjustment when doing the tall target test.I don’t know how much different the clicks would be at the edges, but they’re not the same.”
Should You Perform a WIDE Target Test Too?
What about testing your windage clicks the same way, with a WIDE target test? Bryan Litz says that’s not really necessary: “The wide target test isn’t as important for a couple reasons. First, you typically don’t dial nearly as much wind as you do elevation. Second, your dialed windage is a guess to begin with; a moving average that’s different for every shot. Whereas you stand to gain a lot by nailing vertical down to the click, the same is not true of windage. If there’s a 5% error in your scope’s windage tracking, you’d never know it.”
Verifying Scope Level With Tall Target Test
Bryan says: “While setting up your Tall Target Test, you should also verify that your scope level is mounted and aligned properly. This is critical to insuring that you’ll have a long range horizontal zero when you dial on a bunch of elevation for long range shots. This is a requirement for all kinds of long range shooting. Without a properly-mounted scope level (verified on a Tall Target), you really can’t guarantee your horizontal zero at long range.”
NOTE: For ‘known-distance’ competition, this is the only mandatory part of the tall target test, since slight variations in elevation click-values are not that important once you’re centered “on target” at a known distance.
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On its YouTube Channel, the USAMU offers “Pro Tips” videos providing expert instruction on rifle marksmanship. One helpful video covers up/down angle shooting. In the video, SFC Emil Praslick III, one of America’s best long-range shooting coaches, explains how to determine up/down angle, and how to compensate for the angle using scope clicks. Praslick explains how gravity always works as a constant relative to the flat-ground distance to the target (which is distinct from the actual straight-line distance to target.)
The flat-ground distance is the actual distance over which the bullet will be affected by gravity. Use this as the basis for your elevation corrections. As Praslick explains, “this [flat-ground] distance will get less and less as the angle to the target increases [either up or down].” Once you know the straight-line distance to the target AND the exact angle of your shot, simple math lets you calculate the flat-ground distance to the target. Basically, to determine your flat-ground distance to target, you multiply the cosine of the shot angle by the measured straight-line distance to the target.
Application to Long-Range Hunting Since the effects of angles increase with distance, Praslick explains that: “Unless the angle is extremely severe, [a hunter] really won’t notice these effects at ranges of 200 yards or less.” However, for long shots, hunters definitely need to compensate when taking angled shots. Praslick recommends that hunters print out a small chart with the cosines of common angles (20°, 25°, 30° etc.). In addition, hunters need an accurate ballistic table for their rifle and particular ammo. This should show the elevation corrections (in MOA or clicks), for 200 yards to the maximum range at which you may take a shot.
SFC Emil Praslick III is an instructor/coach with the USAMU. He also has served as a coach and “wind guru” with numerous U.S. Teams in international competition, including the U.S. Palma Team, which recently participated in the World Long-Range Fullbore Rifle Championship in Australia. Praslick has also coached the U.S. F-Open Class Team.
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New S1 and S5 Knurled Dials can be user-installed in place of older Leupold turret caps.
Leupold & Stevens makes good scopes, but the standard turrets with screw-on caps are inconvenient for some users. It’s too easy to misplace the caps. Also the standard turrets are not the easiest to grip, particularly with gloved hands. To improve the “gripability” of its scope turrets, Leupold now offers new S1 and S5 screw-on knurled dials that fit in place of the cap covers. These aluminum dials offer large, knurled surfaces that are easy to grip, even when wearing gloves. “These screw-on dials mean no more lost caps or the need for a coin to make adjustments in the field,” said Tim Lesser, Leupold’s Product Development Director. The S1 is for MOA scopes while the S5 is for MIL scopes.
The S1 and S5 dials simply replace Leupold’s screw-on turret caps, so the user can install these easily without tools. It is NOT necessary to send your scope(s) back to the factory. Just remove the caps on your windage and elevation turrets, and screw the knurled dials in their place. The S1/S5 dials automatically align with the adjustment slot and securely tighten down. These dials are interchangeable between different riflescopes in the field. MSRP is $50 per dial set (either S1 or S5).
The S1 dial is engraved in ¼-MOA increments while the S5 (for mil-based turrets) is marked in 0.1 MIL. Both come with a locking zero stop and can be equipped with the Custom Dial System® (CDS) through the Leupold Custom Shop. The Leupold S1 and S5 dials are compatible with most Leupold riflescopes with click adjustments, with the exception of the VX-1 series and older riflescopes with friction adjustments. For those with bullet-drop-compensating reticles, the S1 and S5 are completely compatible. The screw on dials are covered by Leupold’s full lifetime guarantee.
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In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.
Reader Lindy explains how to check your clicks: “First, make sure the rifle is not loaded. Take a 40″ or longer carpenter’s ruler, and put a very visible mark (such as the center of an orange Shoot’N’C dot), at 37.7 inches. (On mine, I placed two dots side by side every 5 inches, so I could quickly count the dots.) Mount the ruler vertically (zero at top) exactly 100 yards away, carefully measured.
Verifying Scope Level With Tall Target Test
A varmint shooter’s target is not conveniently placed at a fixed, known distance as it is for a benchrester. The varminter must repeatedly make corrections for bullet drop as he moves from closer targets to more distant targets and back again. 
Minority View–Hold-Over is Better
The ability to read the wind is what separates good shooters from great shooters. If you want to learn wind-doping from one of the best, watch this video with 2010 National High Power Champion (and U.S. Army 2010 Soldier of the Year) Sherri Gallagher. Part of the USAMU’s Pro Tips Video Series, this video covers the basics of wind reading including: Determining wind direction and speed, Bracketing Wind, Reading Mirage, and Adjusting to cross-winds using both sight/scope adjustments and hold-off methods. Correctly determining wind angle is vital, Sheri explains, because a wind at a 90-degree angle has much more of an effect on bullet lateral movement than a headwind or tailwind. Wind speed, of course, is just as important as wind angle. To calculate wind speed, Sherri recommends “Wind Bracketing”: [This] is where you take the estimate of the highest possible condition and the lowest possible condition and [then] take the average of the two.”
On its 
Since the effects of angles increase with distance, Praslick explains that: “Unless the angle is extremely severe, [a hunter] really won’t notice these effects at ranges of 200 yards or less.” However, for long shots, hunters definitely need to compensate when taking angled shots. Praslick recommends that hunters print out a small chart with the cosines of common angles (20°, 25°, 30° etc.). In addition, hunters need an accurate ballistic table for their rifle and particular ammo. This should show the elevation corrections (in MOA or clicks), for 200 yards to the maximum range at which you may take a shot.
