“The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.” — William Arthur Ward
Readers often ask us: “Is there a decent, easy-to-comprehend book that can help my wind-reading?” Many of our Forum members have recommended The Wind Book for Rifle Shooters by Linda Miller and Keith Cunningham.
New Hardback Edition Releases February 19th
A NEW hardback edition of The Wind Book will released on February 19, 2019. This 152-page book, first published in 2007, is a very informative resource. But you don’t have to take our word for it. If you click this link, you can read book excerpts and decide for yourself. When the Amazon page opens, click the book cover (labeled “Look Inside”) and another screen will appear. This lets you preview the first few chapters, and see some illustrations. Along with the new hardback edition ($21.99) Amazon offers a Kindle (eBook) edition for $14.99.
Other books cover wind reading in a broader discussion of ballistics or long-range shooting, such as Applied Ballistics for Long-Range Shooting by Bryan Litz. But the Miller & Cunningham book is ALL about wind reading from cover to cover, and that is its strength. The book focuses on real world skills that can help you accurately gauge wind angle, wind velocity, and wind cycles.
All other factors being equal, it is your ability to read the wind that will make the most difference in your shooting accuracy. The better you understand the behavior of the wind, the better you will understand the behavior of your bullet. — Wind Book for Rifle Shooters
The Wind Book for Rifle Shooters covers techniques and tactics used by expert wind-readers. There are numerous charts and illustrations. The authors show you how to put together a simple wind-reading “toolbox” for calculating wind speed, direction, deflection and drift. Then they explain how to use these tools to read flags and mirage, record and interpret your observations, and time your shots to compensate for wind. Here are two reviews from actual book buyers:
I believe this is a must-have book if you are a long-range sport shooter. I compete in F-Class Open and when I first purchased this book and read it from cover to cover, it helped me understand wind reading and making accurate scope corrections. Buy this book, read it, put into practice what it tells you, you will not be disappointed. — P. Janzso
If you have one book for wind reading, this should be it. Whether you’re a novice or experienced wind shooter this book has something for you. It covers how to get wind speed and direction from flags, mirage, and natural phenomenon. In my opinion this is the best book for learning to read wind speed and direction. — Muddler
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In this article, three great champions reveal their wind-calling secrets in video interviews. We first published this “Three Champions” story a few years ago. If you are a competitive shooter, and you want to learn more about reading the wind, you should watch all three of these interviews. These guys are among the best shooters to ever shoulder a rifle, and they have much wisdom to share.
At the 2010 SHOT Show, we had the unique opportunity to corner three “superstars” of High Power shooting, and solicit their wind-reading secrets. In the three videos below (in alphabetical order), Carl Bernosky (10-Time Nat’l High Power Champion), David Tubb (11-time Nat’l High Power Champion and 7-time Nat’l Long-Range Champion), and John Whidden (5-Time Nat’l High Power Long-Range Champion) shared some of the wind-doping strategies that have carried them to victory in the nation’s most competitive shooting matches. This is GOLD folks… no matter what your discipline — be it short-range Benchrest or Long-Range High Power — watch these videos for valuable insights that can help you shoot more accurately, and post higher scores, in all wind conditions.
We were very fortunate to have these three extraordinarily gifted champions reveal their “winning ways”. These guys REALLY know their stuff. I thought to myself: “Wow, this is how a baseball fan might feel if he could assemble Babe Ruth, Hank Aaron, and Ted Williams in the same room, and have them each reveal their hitting secrets.” Editor’s Note: These interviews were conducted before all three men won their most recent National Championships so the introductions may list a lower number of titles won. For example, John Whidden won back-to-back LR Championships in 2016 and 2017/
Top photo courtesy Rifleman’s Journal.
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Riflescopes are mechanical contraptions. One of the sad realities about precision shooting is that, sooner or later, you will experience a scope failure. If you’re lucky it won’t happen in the middle of a National-level competition. And hopefully the failure will be dramatic and unmistakable so you won’t spend months trying to isolate the issue. Unfortunately, scope problems can be erratic or hard to diagnose. You may find yourself with unexplained flyers or a slight degradation of accuracy and you won’t know how to diagnose the problem. And when a 1/8th-MOA-click scope starts failing, it may be hard to recognize the fault immediately, because the POI change may be slight.
When An Expensive Scope Goes Bad
A few seasons back, this editor had a major-brand 8-25x50mm scope go bad. How did I know I had a problem? Well the first sign was a wild “drop-down” flyer at a 600-yard match. After shooting a two-target relay, I took a look at my targets. My first 5-shot group had five shots, fairly well centered, in about 2.2″. Pretty good. Everything was operating fine. Then I looked at the second target. My eye was drawn to four shots, all centered in the 10 Ring, measuring about 2.4″. But then I saw the fifth shot. It was a good 18″ low, straight down from the X. And I really mean straight down — if you drew a plumb line down from the center of the X, it would pass almost through the fifth shot.
Is My Scope Actually Malfunctioning or Is This Driver Error?
That was disconcerting, but since I had never had any trouble with this scope before, I assumed it was a load problem (too little powder?), or simple driver error (maybe I flinched or yanked the trigger?). Accordingly, I didn’t do anything about the scope, figuring the problem was me or the load.
Even expensive scopes can fail, or start to perform erratically — and that can happen without warning, or for no apparent reason. Here are some signs that you may be having scope issues.
1. Click count has changed signficantly from established zero at known range.
2. Noticeably different click “feel” as you rotate turrets, or turrets feel wobbly.
3. Inability to set Adjustable Objective or side focus to get sharp target image.
4. Shot Point of Impact is completely different than click value after elevation/windage change. For example, when you dial 2 MOA “up” but you observe a 6 MOA rise in POI.
Problems Reappear — Huge POI Swings Affirm This Scope is Toast
But, at the next range session, things went downhill fast. In three shots, I did manage to get on steel at 600, with my normal come-up for that distance. Everything seemed fine. So then I switched to paper. We had a buddy in the pits with a walkie-talkie and he radioed that he couldn’t see any bullet holes in the paper after five shots. My spotter said he thought the bullets were impacting in the dirt, just below the paper. OK, I thought, we’ll add 3 MOA up (12 clicks), and that should raise POI 18″ and I should be on paper, near center. That didn’t work — now the bullets were impacting in the berm ABOVE the target frame. The POI had changed over 48″ (8 MOA). (And no I didn’t click too far — I clicked slowly, counting each click out loud as I adjusted the elevation.) OK, to compensate now I took off 8 clicks which should be 2 MOA or 12″. No joy. The POI dropped about 24″ (4 MOA) and the POI also moved moved 18″ right, to the edge of the target.
For the next 20 shots, we kept “chasing center” trying to get the gun zeroed at 600 yards. We never did. After burning a lot of ammo, we gave up. Before stowing the gun for the trip home, I dialed back to my 100-yard zero, which is my normal practice (it’s 47 clicks down from 600-yard zero). I immediately noticed that the “feel” of the elevation knob didn’t seem right. Even though I was pretty much in the center of my elevation (I have a +20 MOA scope mount), the clicks felt really tight — as they do when you’re at the very limit of travel. There was a lot of resistance in the clicks and they didn’t seem to move the right amount. And it seemed that I’d have four or five clicks that were “bunched up” with a lot of resistance, and then the next click would have almost no resistance and seem to jump. It’s hard to describe, but it was like winding a spring that erratically moved from tight to very loose.
At this point I announced to my shooting buddies: “I think the scope has taken a dump.” I let one buddy work the elevation knob a bit. “That feels weird,” he said: “the clicks aren’t consistent… first it doesn’t want to move, then the clicks jump too easily.”
Convinced that I had a real problem, the scope was packed up and shipped to the manufacturer. So, was I hallucinating? Was my problem really just driver error? I’ve heard plenty of stories about guys who sent scopes in for repair, only to receive their optics back with a terse note saying: “Scope passed inspection and function test 100%. No repairs needed”. So, was my scope really FUBAR? You bet it was. When the scope came back from the factory, the Repair Record stated that nearly all the internal mechanicals had been replaced or fixed: “Replaced Adjustment Elevation; Replaced Adjustment Windage; Reworked Erector System; Reworked Selector; Reworked Parallax Control.”
How to Diagnose Scope Problems
When you see your groups open up, there’s a very good chance this is due to poor wind-reading, or other “driver error”. But my experience showed me that sometimes scopes do go bad. When your accuracy degrades without any other reasonable explanation, the cause of the problem may well be your optics. Here are some of the “symptoms” of scope troubles:
1. Large shot-to-shot variance in Point of Impact with known accurate loads.
2. Uneven tracking (either vertical or horizontal).
3. Change of Point of Impact does not correspond to click inputs.
4. Inability to zero in reasonable number of shots.
5. Unexpected changes in needed click values (compared to previous come-ups).
6. Visible shift in reticle from center of view.
7. Changed “feel” or resistance when clicking; or uneven click-to-click “feel”.
8. Inability to set parallax to achieve sharpness.
9. Turrets or other controls feel wobbly or loose.
10. Internal scope components rattle when gun is moved.
Source of Problem Unknown, but I Have a Theory
Although my scope came with a slightly canted reticle from the factory, it had otherwise functioned without a hitch for many years. I was able to go back and forth between 100-yard zero and 600-yard zero with perfect repeatability for over five years. I had confidence in that scope. Why did it fail when it did? My theory is side-loading on the turrets. I used to carry the gun in a thick soft case. I recently switched to an aluminum-sided hard case that has pretty dense egg-crate foam inside. I noticed it took some effort to close the case, though it was more than big enough, width-wise, to hold the gun. My thinking is that the foam wasn’t compressing enough, resulting in a side-load on the windage turret when the case was clamped shut. This is just my best guess; it may not be the real source of the problem. Remember, as I explained in the beginning of this story, sometimes scopes — just like any mechanical system — simply stop working for no apparent reason.
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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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This article first appeared in 2014. We are reprising it at the request of many readers who are fans of the .30-06 cartridge.
The “Old Warhorse” .30-06 Springfield cartridge is not dead. That’s the conclusion of Forum member Rick M., who has compared the 1000-yard performance of his .30-06 rifle with that of a rig chambered for the more modern, mid-sized 6.4×47 Lapua cartridge. In 12-16 mph full-value winds, the “inefficient and antiquated” .30-06 ruled. Rick reports:
“I was shooting my .30-06 this past Sunday afternoon from 1000 yards. The wind was hitting 12-16 mph with a steady 9 O’clock (full value) wind direction. My shooting buddy Jeff was shooting his 6.5×47 Lapua with 123gr Scenar bullets pushed by Varget. Jeff needed 13 MOA left windage to keep his 6.5x47L rounds inside the Palma 10 Ring. By contrast I only needed 11.5 MOA left windage with my .30-06. I was shooting my ’06 using the 185gr Berger VLD target bullet with H4350. I managed the same POI yet the .30-caliber bullet only needed 11.5 MOA windage. That’s significant. From this experience I’ve concluded that the Old Warhorse ain’t quite dead yet!”
Rick likes his “outdated” .30-06 rifle. He says it can deliver surprisingly good performance at long range:
“To many of the younger generation, the Old Warhorse .30-06 is ‘outdated’ but I can guarantee that the .30-06 Springfield is a VERY ACCURATE cartridge for 1000-yard shooting (and even out further if need be). With some of the advanced powders that we have today, the .30-06 will surprise many shooters with what it’s capable of doing in a good rifle with the right rate of twist. My rifle has a 1:10″ twist rate and I had it short-throated so that, as the throat erodes with time, I could just seat the bullets out further and keep right on shooting. My recent load is Berger 185gr Target VLDs pushed by IMR 4350. This is a very accurate load that moves this bullet along at 2825 fps.”
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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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For many riflemen, reading the wind is the toughest challenge in long-range shooting. Wind speeds and directions can change rapidly, mirage can be misleading, and terrain features can cause hard-to-predict effects. To become a competent wind reader, you need range-time and expert mentoring. In the latter department, Frank Galli, founder of Sniper’s Hide, has just released a new digital resource: Wind Reading Basics for the Tactical Shooter.
Wind Reading Basics is much more than an eBook — it has charts, instructions for ballistic calculators, and even embedded videos. Galli explains: “We break down the formulas, walk you through using a ballistic computer, and give you all the information in one place. From videos, to useful charts, we make it simple to get started. It’s all about having a plan, and we give you that plan.”
Galli’s Wind Reading Basics, priced at $11.99, can be downloaded from iTunes for iPads, iPhones and iOS compatible devices. Here are sample sections from the eBook (which includes videos):
In this NSSF Video, Ryan Cleckner, a former Sniper Instructor for the 1st Ranger Battalion, defines the term, “Minute of Angle” (MOA) and explains how you can adjust for windage and elevation using 1/4 or 1/8 MOA clicks on your scope. This allows you to sight-in precisely and compensate for bullet drop at various distances.
For starters, Ryan explains that, when talking about angular degrees, a “minute” is simply 1/60th. So a “Minute of Angle” is simply 1/60th of one degree of a central angle, measured either up and down (for elevation) or side to side (for windage). At 100 yards, 1 MOA equals 1.047″ on the target. This is often rounded to one inch for simplicity. Say, for example, you click up 1 MOA. That is roughly 1 inch at 100 yards, or roughly 4 inches at 400 yards, since the target area measured by 1 MOA increases in linear fashion with the distance.
Story sourced by Edlongrange.
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Readers often ask us: “Is there a decent, easy-to-comprehend book that can help my wind-reading?” Many of our Forum members have recommended The Wind Book for Rifle Shooters by Linda Miller and Keith Cunningham. This 146-page book, published in 2007, is a very informative resource. But you don’t have to take our word for it. If you click this link, you can read book excerpts and decide for yourself. When the Amazon page opens, click the book cover (labeled “Look Inside”) and another screen will appear. This lets you preview the first few chapters, and see some illustrations.
Other books cover wind reading in a broader discussion of ballistics or long-range shooting, such as Applied Ballistics for Long-Range Shooting by Bryan Litz. But the Miller & Cunningham book is ALL about wind reading from cover to cover, and that is its strength. The book focuses on real world skills that can help you accurately gauge wind angle, wind velocity, and wind cycles.
All other factors being equal, it is your ability to read the wind that will make the most difference in your shooting accuracy. The better you understand the behavior of the wind, the better you will understand the behavior of your bullet. — Wind Book for Rifle Shooters
The Wind Book for Rifle Shooters cover the techniques and tactics used by expert wind-readers. There are numerous charts and illustrations. The authors show you how to put together a simple wind-reading “toolbox” for calculating wind speed, direction, deflection and drift. Then they explain how to use these tools to read flags and mirage, record and interpret your observations, and time your shots to compensate for wind. Here are some reviews from actual book buyers:
I believe this is a must-have book if you are a long-range sport shooter. I compete in F-Class Open and when I first purchased this book and read it from cover to cover, it helped me understand wind reading and making accurate scope corrections. Buy this book, read it, put into practice what it tells you, you will not be disappointed. — P. Janzso
If you have one book for wind reading, this should be it. Whether you’re a novice or experienced wind shooter this book has something for you. It covers how to get wind speed and direction from flags, mirage, and natural phenomenon. In my opinion this is the best book for learning to read wind speed and direction. — Muddler
As far as I know this is the only book of its type. It’s very well written in a way that’s easy to understand for such a complex subject. The charts and graphs are extremely helpful. It’s a bit on the short side at about 146 pages but still packed with knowledge. — R. Johnson
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The new-for-2014 Caldwell Crosswind Professional Wind Meter does much more than measure wind velocity. Along with Current Wind Speed, this device will measure and display: Average Wind Speed, Max Wind Gust, Temperature, Station Pressure, Barometric Pressure, Altitude, Density Altitude and even Wind Chill factor. Select among mph, ft/min, km/h, m/s, or knots for the wind speed units.
The swiveling impeller head (set parallel to barrel) allows you to determine an interpolated 90° crosswind value to use in your ballistics calculations. This eliminates a lot of guesswork.
You might say, “Why do I need a rotating head, I can just turn the whole wind meter to align the impeller axis with the wind?” Yes you can, but then you merely get a raw speed value, and you have to guesstimate the wind angle, and then calculate your actual windage correction based on the vector.
The rotating impeller ring on the Caldwell simplifies the job of calculating windage. The swivel head is designed to show an effective 90-degree crosswind value, no matter what the actual wind direction. Here’s how it works. Hold the unit with the display screen facing you. Then rotate the impeller head until it aligns with the barrel axis (bullet line of flight). The plastic shell surrounding the impeller is specifically designed so that the blades will spin faster or slower depending on the true wind angle. This allows the unit to estimate the effective 90-degree crosswind value (for your ballistics program). Pretty clever eh? See diagram to understand how this works:
This unit comes complete with rotating anemometer head, protective holster case, and one CR2032 battery. The unit has an auto “Power-Off” feature to preserve battery life. There is also a “Data Hold” function plus an LCD Backlight. NOTE: When figuring effective 90° crosswind values, Caldwell recommends using Average Wind Speed mode rather than Current Wind Speed.
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Need a high-quality front rest at an affordable price? Here are some of the best deals we’ve seen in years. Bullets.com just announced a massive price cut on its Bald Eagle brand front rests. Both the regular rests and the deluxe rests with flex-shaft windage adjustments are on sale. (These windage-adjustable rests are great for F-Class shooting.) Windage-adjustable rests start at just $215.00, while the conventional rests are marked down to $179.95 (less than half the original price!) Choose from Cast Iron or Aluminum bases, triangle or slingshot (wishbone) footprints. These are high-quality rests, with CNC-machined parts. They have been used successfully by many top F-Class and benchrest shooters.
Bullets.com tells us: “These rests were originally designed by a Benchrest shooter and refined by a member of the U.S F-Class Open Rifle Team. The rests have been thoroughly tested and proven to be reliable and capable of quick and accurate adjustments during string shooting.”
Bald Eagle Shooting Rests with Windage System ON SALE
BE1004 – Triangle, Aluminum, Reg. $425.00 — SALE $215.00
BE1005 – Slingshot, Aluminum, Reg. $425.00 — SALE $215.00
BE1006 – Slingshot, Cast Iron, Reg. $475.00 — SALE $235.00
Bald Eagle Shooting Rests without Windage System ON SALE
BE1128 – Triangle, Aluminum, Reg. $375.00 — SALE $179.95
BE1130 – Slingshot, Cast Iron, Reg. $399.95 — SALE $179.95
BE1129 – Slingshot, Aluminum, Reg. $375.00 — SALE $179.95
Along with offering super deals on front rests, Bullets.com has also slashed prices on its front and rear sand bags. Front Bags are marked dow to $27.50, while Rear Bags are on sale from $52.50 – $64.50. Large-diameter F-Class rest feet are also on sale currently. Get more details at Bullets.com.
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Well, yes, that headline is a come-on. But there’s truth in the promise. The “miracle device” to which we refer is a simple wind indicator aka “windflag”. Remarkably, many shooters who spend $3000.00 or more on a precision rifle never bother to set up windflags, or even simple wood stakes with some ribbon to show the wind. Whether you’re a competitive shooter, a varminter, or someone who just likes to punch small groups, you should always take a set of windflags (or some kind of wind indicators) when you head to the range or the prairie dog fields. And yes, if you pay attention to your windflags, you can easily cut your group sizes in half. Here’s proof…
Miss a 5 mph Shift and Double Your Group Size
The table below records the effect of a 5 mph crosswind at 100, 200, and 300 yards. You may be thinking, “well, I’d never miss a 5 mph let-off.” Consider this — if a gentle 2.5 mph breeze switches from 3 o’clock (R to L) to 9 o’clock (L to R), you’ve just missed a 5 mph net change. What will that do to your group? Look at the table to find out.
Values from Point Blank Ballistics software for 500′ elevation and 70° temperature.
Imagine you have a 6mm rifle that shoots half-MOA consistently in no-wind conditions. What happens if you miss a 5 mph shift (the equivalent of a full reversal of a 2.5 mph crosswind)? Well, if you’re shooting a 68gr flatbase bullet, your shot is going to move about 0.49″ at 100 yards, nearly doubling your group size. With a 105gr VLD, the bullet moves 0.28″ … not as much to be sure, but still enough to ruin a nice small group. What about an AR15, shooting 55-grainers at 3300 fps? Well, if you miss that same 5 mph shift, your low-BC bullet moves 0.68″. That pushes a half-inch group well past an inch. If you had a half-MOA capable AR, now it’s shooting worse than 1 MOA. And, as you might expect, the wind effects at 200 and 300 yards are even more dramatic. If you miss a 5 mph, full-value wind change, your 300-yard group could easily expand by 2.5″ or more.
Forest of Windflags at World Benchrest Championships in France in 2011
If you’ve already invested in an accurate rifle with a good barrel, you are “throwing away” accuracy if you shoot without wind flags. You can spend a ton of money on fancy shooting accessories (such as expensive front rests and spotting scopes) but, dollar for dollar, nothing will potentially improve your shooting as much as a good set of windflags, used religiously.
The web-based JBM Ballistics Program is one of the most sophisticated and accurate ballistics calculators available — and it’s free. The latest version of the JBM Trajectory Calculator includes field-test-derived actual G7 BCs, as well as bullet drag data from Lapua’s Doppler radar testing. You can also change weather variables, and generate come-up tables for distances out to 3000 yards.
Whenever we have web access, the JBM program is our “go-to” resource for dependable ballistics calculations. In our experience, with most bullets, if you input all the correct variables for the JBM program, it should get you within 1/2 moa (2 clicks), at 600 yards.
New URLs for JBM Ballistics Calculators
With the release of the latest version of the JBM program, some URLs for the calculations pages have changed. You may want to update your bookmarks with the following web addresses:
Here’s something that can save you lots of time and aggravation on a varminting trip. This little $110 gizmo is great for varmint hunters and any one who needs to make a quick shot in shifty wind conditions. Instead of the traditional 1/4-MOA hash marks, the Kenton windage turret features markers corresponding to the wind drift your ammo will encounter at various distances (with 10 mph full value winds). You just dial the distance.
Custom-Calibrated Windage Knobs
Kenton Industries’ Tuned Windage Compensator (TWC) has built-in windage marks for 10 mph cross-winds at 100-1000 yards. How do they do that? Well the knobs are calibrated either for specific calibers/loads, or they can make custom knobs using your observed field data. The knobs can compensate for various wind speeds (2-20 mph) and angles (15°- 90°), by applying some simple conversion ratios. As a general rule, with a “full-value”, i.e. 90°, crosswind, the wind drift will go up or down in direct proportion to the change in windspeed. That means, for example, a 10 mph crosswind will push the bullet twice as much sideways as a 5 mph crosswind.
Two versions of Kenton’s TWC knobs are offered. The $109.95 TWC #1 features calculated ballistics for standardized factory ammo for the caliber and barrel length you specify. The $109.95 TWC #2 feature customized windage settings based on bullet BC, environmental conditions, elevation, and ballistic information you provide.
Custom Elevation Knobs
Kenton also makes a $109.95 elevation-compensating TTC knob, that can be customized to your rifle. With this elevation turret, yardages are marked in 50-yard increments, and you can literally just “dial in your distance”. However, to work effectively the TTC knob must be tailored to a particular load (velocity and bullet). Moreover, actual bullet drop will differ with changes in altitude, temperature, and shooting angle — so it’s not as simple as it sounds, and you may need multiple knobs if you shoot a variety of loads. Kenton offers it TTC #1 model calibrated for standardized factory ammo. The TTC #2 is calibrated out to the maximum effective range of your cartridge based on bullet type, muzzle velocity, altitude, and temperature. Select the type of yardage format to be used. The #2 is recommended for wildcatters or for those who want to adjust to specific conditions. Lastly, a TTC #3 elevation knob is offered that relies on the purchaser’s actual recorded drop data from the field. The TTC #3 elevation knob will be calibrated based on the click-value or MOA you provide for each 50-yard increment.
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Readers often ask us: “Is there a decent, easy-to-comprehend book that can help my wind-reading?” Many of our Forum members have recommended The Wind Book for Rifle Shooters by Linda Miller and Keith Cunningham.
For the next 20 shots, we kept “chasing center” trying to get the gun zeroed at 600 yards. We never did. After burning a lot of ammo, we gave up. Before stowing the gun for the trip home, I dialed back to my 100-yard zero, which is my normal practice (it’s 47 clicks down from 600-yard zero). I immediately noticed that the “feel” of the elevation knob didn’t seem right. Even though I was pretty much in the center of my elevation (I have a +20 MOA scope mount), the clicks felt really tight — as they do when you’re at the very limit of travel. There was a lot of resistance in the clicks and they didn’t seem to move the right amount. And it seemed that I’d have four or five clicks that were “bunched up” with a lot of resistance, and then the next click would have almost no resistance and seem to jump. It’s hard to describe, but it was like winding a spring that erratically moved from tight to very loose.
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.)
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.”
Well, yes, that headline is a come-on. But there’s truth in the promise. The “miracle device” to which we refer is a simple wind indicator aka “windflag”. Remarkably, many shooters who spend $3000.00 or more on a precision rifle never bother to set up windflags, or even simple wood stakes with some ribbon to show the wind. Whether you’re a competitive shooter, a varminter, or someone who just likes to punch small groups, you should always take a set of windflags (or some kind of wind indicators) when you head to the range or the prairie dog fields. And yes, if you pay attention to your windflags, you can easily cut your group sizes in half. Here’s proof…
The web-based 
Here’s something that can save you lots of time and aggravation on a varminting trip. This little $110 gizmo is great for varmint hunters and any one who needs to make a quick shot in shifty wind conditions. Instead of the traditional 1/4-MOA hash marks, the Kenton windage turret features markers corresponding to the wind drift your ammo will encounter at various distances (with 10 mph full value winds). You just dial the distance.
