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November 22nd, 2022

Bullet Flight Video Reveals Shock Wave and Bullet Base Drag

Science Accuracy Academy bullet video Schlieren movie shock wave capture

Ever wondered what the air around a moving supersonic bullet really looks like? Check out this video from the Bryan Litz Ballistics Facebook page. This is a Schlieren video* of a 6mm 109gr Berger LRHT bullet at about 2800 fps as fired from Francis Colon’s PRS rifle at the Applied Ballistics Lab.


Bryan Litz notes: “You can clearly see the compression (shock) wave at the front of the bullet. A compression wave is formed when the air has to move faster than the speed of sound to get out of the way, which is certainly the case for this bullet which is moving about 2.5 times the speed of sound (Mach 2.5).

That shock wave is the ‘snap’ you hear when bullets fly past you if/when you’re downrange. Also, compressing the air into a shockwave takes energy, and that energy comes directly out of the forward velocity of your bullet and gets converted into heat and noise as the shock wave forms and dissipates.

The turbulent wake at the base of the bullet shows where/how base drag applies. The third and smallest component of drag for a supersonic bullet is skin friction drag, which is a viscous boundary layer effect, and is the least visible in this image. So as you head to the range or the hunting stand, think about the absolute violence your bullets are committing in the atmosphere, before they even reach the target!”

Subscribe to the Science of Accuracy Academy for more precision rifle and long range shooting content. LINK: TheScienceofAccuracy.com.

Science of Academy Contest
The Science of Accuracy Academy is currently running a contest for new subscribers. The winner receives a Vortex Fury HD 5000 Laser Rangefinder Binocular unit with Applied Ballistics functionality. Act soon — the deadline to enter is November 23, 2022 at 1:00 pm Eastern.

Science Accuracy Academy vortex rangefinder binoculars contest prize bryan litz


* Schlieren imaging makes air flow features visible. SEE Schlieren Photography Wikipedia page.

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November 21st, 2022

How Altitude and Barometric Pressure Affect Projectile Ballistics

altitude ballistics zeiss LRP S5 318-50 FFP scope
Photo shows the new ZEISS LRP S5 318-50 first focal plane (FFP) scope.

“A bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.”

Last month a good friend ventured to the high country of Colorado to pursue elk. He recently zeroed his rifle in California, at a range just a few hundred feet Above Mean Sea Level (AMSL). He wondered if the higher altitude in Colorado could alter his ballistics. The answer is a definite yes. However the good news is that free ballistics calculators can help you plot reliable drop charts for various shooting locations, high or low.

Suunto AltimeterThe question has been posed: “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, at higher altitudes, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ AMSL (Above Mean Sea Level) or less. I’ll need about 29-30 MOA to get from 100 yards to 1000 yards with a Berger 155gr VLD at 2960 fps. By contrast, in Raton, NM, located at 6600′ AMSL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect. It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet AMSL), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

To learn more about all aspects of Exterior Ballistics, Hornady has a useful discussion of External Ballistics including the effects of altitude and temperature. To dig deeper, Sierra Bullets has a comprehensive Exterior Ballistics Resource Page with multiple sections from the Sierra Manual (4th and 5th Editions), including:

Section 3.0: Exterior Ballistic Effects on Bullet Flight
Section 3.1: Effects of Altitude and Atmospheric Conditions
Section 3.2: Effects of Wind
Section 3.3: Effects of Shooting Uphill or Downhill

Example from Section 3.0: “When a bullet flies through the air, two types of forces act on the bullet to determine its path (trajectory) through the air. The first is gravitational force; the other is aerodynamics. Several kinds of aerodynamic forces act on a bullet: drag, lift, side forces, Magnus force, spin damping force, pitch damping force, and Magnus cross force. The most important of these aerodynamic forces is drag. All the others are very small in comparison when the bullet is spin-stabilized.”

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July 31st, 2022

“How Do Bullets Fly” — Great Online Resource with Smart Science

Bullet External Ballistics
“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag….

Ruprecht Nennstiel, a forensic ballistics expert from Wiesbaden, Germany, has authored a great resource about bullet behavior in flight. Nennstiel’s comprehensive article, How Do Bullets Fly, explains all the forces which affect bullet flight including gravity, wind, gyroscopic effects, aerodynamic drag, and lift. Nennstiel even explains the rather arcane Magnus Force and Coriolis Effect which come into play at long ranges. Nennstiel’s remarkable resource contains many useful illustrations plus new experimental observations of bullets fired from small arms, both at short and at long ranges.

Shadowgraph of .308 Winchester Bullet

Bullet External Ballistics

A convenient index is provided so you can study each particular force in sequence. Writing with clear, precise prose, Nennstiel explains each key factor that affects external ballistics. For starters, we all know that bullets spin when launched from a rifled barrel. But Nennstiel explains in greater detail how this spinning creates gyroscopic stability:

“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag, the plane, formed by the velocity vector ‘v’ and the longitudinal axis of the bullet. In the absence of spin, the yaw angle ‘δ’ would grow and the bullet would tumble.

If the bullet has sufficient spin, saying if it rotates fast enough about its axis of form, the gyroscopic effect takes place: the bullet’s longitudinal axis moves into the direction of the overturning moment, perpendicular to the plane of drag. This axis shift however alters the plane of drag, which then rotates about the velocity vector. This movement is called precession or slow mode oscillation.”

Raise Your Ballistic IQ
Though comprehensible to the average reader with some grounding in basic physics, Nennstiel’s work is really the equivalent of a Ph.D thesis in external ballistics. You could easily spend hours reading (and re-reading) all the primary material as well as the detailed FAQ section. But we think it’s worth plowing into How Do Bullets Fly from start to finish. We suggest you bookmark the page for future reference. You can also download the complete article for future reference and offline reading.

CLICK HERE for “How Do Bullets Fly” complete text.

(1.2 MB .zip file)

Photo and diagram © 2005-2009 Ruprecht Nennstiel, All Rights Reserved.

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July 14th, 2022

Long Range Shooting Tips from Ballistics Guru Bryan Litz

NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Berger SW Nationals Bryan LitzThe 2022 NRA Long Range National Matches and Palma Matches at Camp Atterbury, Indiana kick off soon. The NRA’s Long Range matches will run July 24-29, 2022. In addition, the CMP’s National Long Range Matches will run August 9-13, 2022 at Camp Perry in Ohio.

Today we share some smart tips from a past F-Class and Sling Champion who is both a great shooter AND a ballistics wizard. In 2015, Bryan Litz won the F-TR Mid-Range AND Long-Range National Championships hosted at Ben Avery. And at the 2014 Berger SW Nationals (SWN), Bryan took top honors among all sling shooters. If you only know Bryan Litz from his Applied Ballistics Books and DVDs, you may not realize that this guy is a also great marksman along with being an actual rocket scientist!

Given his impressive track record in both F-Class and Palma (Fullbore) out to 1000 yards, we asked Bryan if he had any advice for other long-range competitors.

First Bryan provided three tips concerning Ballistics, his special area of expertise. Next Bryan offered three more general tips about long-range competition — how to analyze your shooting, how to choose your ‘wind strategy’, and how to avoid the most costly mistakes, i.e. how to avoid the “train-wrecks”.

Bryan Litz won the 2015 F-TR Mid-Range and Long-Range Championships with this sleek rig:
NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Litz Ballistics Tips

Ballistics TIP ONE. If you’re having trouble getting your ballistic software to match actual drops, you need to look at a number of possible reasons. Here are some common issues that can cause problems.

Click Values Are Not Exact. Scopes and iron sights don’t always produce accurate adjustments. In other words, if your ballistics program predicts 30 MOA of drop, and you dial 30 MOA but hit low, it might be that your sight actually only moved 28 MOA (for example). To see if your sight is adjusting accurately, shoot a tall target at 100 yards and measure group separation when dialing your sight.

Barometric vs. Station Pressure. This is a commonly misunderstood input to ballistics programs. You can avoid this pitfall by remembering the following: station pressure is the actual measured pressure at your location, and you don’t need to tell the program your altitude when using station pressure. Barometric pressure is corrected for sea level. If you’re using barometric pressure, you also have to input your altitude.

Muzzle Velocity. Chronographs are not always as accurate as shooters think they are — your true MV may be off by 10-20 fps (or more). If your drop is different than predicted at long range, it might be because your muzzle velocity input is wrong.

Mixing Up BC (G1 vs. G7). Knowledgeable long range shooters know that the G7 standard is a more representative standard for modern LR bullets. However, using G7 BCs isn’t just a matter of clicking the ‘G7′ option in the program. The numeric value of the BC is different for G1 and G7. For example, the G1 BC of the Berger 155.5 grain Fullbore bullet is .464 but the G7 BC is .237. If you were to enter .464 but click on G7, the results would be way off.

Ballistics TIP TWO. A properly installed level is absolutely essential for long range shooting. Without a good level reference, your long range wind zero will be off due to minor canting of the rifle from side to side. You can verify that your level is installed correctly on a 100-yard ‘tall target’. Draw a plumb line straight up the target and verify that your groups track straight up this line as you go up in elevation.

Ballistics TIP THREE. If your long range ballistic predictions aren’t tracking, always come back and verify your 100-yard zero. Sometimes a simple zero shift can be misconstrued as errors in long range ballistics predictions.

Bryan Litz Tips

Litz Competition Shooting Tips

Competition TIP ONE. Improving your scores in long range competition is a constant process of self-assessment. After each match, carefully analyze how you lost points and make a plan to improve. Beginning shooters will lose a lot of points to fundamental things like sight alignment and trigger control. Veteran shooters will lose far fewer points to a smaller list of mistakes. At every step along the way, always ask yourself why you’re losing points and address the issues. Sometimes the weak links that you need to work on aren’t your favorite thing to do, and success will take work in these areas as well.

CMP Long range camp Perry Nationals National Championships Bryan Litz

Competition TIP TWO. Select your wind shooting strategy carefully. For beginners and veterans, most points are typically lost to wind. Successful shooters put a lot of thought into their approach to wind shooting. Sometimes it’s best to shoot fast and minimize the changes you’ll have to navigate. Other times it’s best to wait out a condition which may take several minutes. Develop a comfortable rest position so you have an easier time waiting when you should be waiting.

Competition TIP THREE. Actively avoid major train wrecks. Sounds obvious but it happens a lot. Select equipment that is reliable, get comfortable with it and have back-ups for important things. Don’t load on the verge of max pressure, don’t go to an important match with a barrel that’s near shot out, physically check tightness of all important screws prior to shooting each string. Observe what train wrecks you and others experience, and put measures in place to avoid them.

NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Electronic High Power Targets for 2022 at Camp Atterbury
This year, for the first time, electronic targets will be used at Camp Atterbury during the NRA High Power National Championships. NRA Competitive Shooting Deputy Director Aaron Farmer posted: “We will have up to 40 targets using Silver Mountain electronic target systems. Competitors will be squadded on a target and then continue to shoot on the same target all week. The only thing that will change is the starting relay for the day. We will be running three relays. No pit duty!”

Photos by Steve Fiorenzo

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June 23rd, 2022

Dope for Your Scope — Print Handy Laminated Ballistics Card

laminated ballistics Card print-out

Tactical competitor Zak Smith stores his elevation and wind drift data on a handy laminated data card. To make one, first generate a come-up table, using one of the free online ballistics programs such as JBM Ballistics. You can also put the info in an Excel spreadsheet or MS Word table and print it out.

Above is a sample of a data card. For each distance, the card includes drop in inches, drop in MOA, drop in Mils. It also shows drift for a 10-mph cross wind, expressed in inches, MOA, and mils. Zak explained that “to save space… I printed data every 50 yards. For an actual data-card, I recommend printing data every 20 or 25 yards.” But Zak also advised that you’ll want to customize the card format to keep things simple: “The sample card has multiple sets of data to be more universal. But if you make your own data card, you can reduce the chance of a mistake by keeping it simple.”

Once you have the card you can fold it in half and then have it laminated at a local office store or Kinko’s. Keep this in your pocket, tape it to your stock, or tie the laminated card to your rifle. If you regularly shoot at both low and high elevations, you may want to create multiple cards (since your ballistics change with altitude). To learn more about ballistic tables and data cards, check out the excellent “Practical Long-Range Rifle Shooting–Part 1″ article on Zak’s website.

ballistics data scope coverScope-Cover Mounted Ballistics Table
Another option is to place your ballistics card on the back of the front flip-up scope cover. This set-up is used by Forum member Greg C. (aka “Rem40X”). With your ‘come-up’ table on the flip-up cover you can check your windage and elevation drops easily without having to move out of shooting position.

Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit. And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”

Links for JBM Ballistics Program

JBM Calculations Entry: JBMballistics.com/ballistics/calculators/calculators.shtml

JBM Advanced Trajectory Calculator: JBMballistics.com/cgi-bin/jbmtraj-5.1.cgi

JBM Simple Trajectory Calculator: JBMballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

JBM Trajectory Cards (Come-up Table): JBMballistics.com/cgi-bin/jbmcard-5.1.cgi

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April 14th, 2022

The Right Way to Find Wind Direction with a Kestrel Wind Meter

Kestrel Wind Meter Direction Vane Applied Ballistics

A Kestrel Wind Meter will record wind speed with its impeller wheel. However, to get the most accurate wind velocity reading, you need to have your Kestrel properly aligned with the wind direction. To find wind direction, first orient the Kestrel so that the impeller runs at minimal speed (or stops), and only then turn the BACK of the Kestrel into the wind direction. Do NOT simply rotate the Kestrel’s back panel looking for the highest wind speed reading — that’s not the correct method for finding wind direction. Rotate the side of the Kestrel into the wind first, aiming for minimal impeller movement. The correct procedure is explained below by the experts at Applied Ballistics.

How to Find the Wind Direction with a Kestrel Wind Meter

Here is the correct way to determine wind direction with a Kestrel wind meter when you have no environmental aids — no other tools than a Kestrel. (NOTE: To determine wind direction, a mounted Wind Vane is the most effective tool, but you can also look at flags, blowing grass, or even the lanyard on your Kestrel).

Step 1: Find the wind’s general direction.

Step 2: Rotate the Wind Meter 90 degrees, so that the wind is impacting the side (and not the back) of the wind meter, while still being able to see the impeller.

Step 3: Fine-tune the direction until the impeller drastically slows, or comes to a complete stop (a complete stop is preferred). If the impeller won’t come to a complete stop, find the direction which has the lowest impact on the impeller.

Step 4: Turn the BACK of the Kestrel towards the direction from which the wind is blowing. Then press the capture button, and record your wind speed.

Do NOT simply point the Kestrel’s back into the wind until you get the highest wind speed — that’s not the correct method.

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February 13th, 2022

G1 vs. G7 Ballistic Coefficients — What You Need to Know

G1 G7 BC drag models

Over the past 12 months, this article was one of the TOP 20 most-read Daily Bulletin features. We’re reprising it today for those who may have missed it the first time. The above diagram comes from a TiborasurasRex YouTube Video comparing G1 and G7 BC models. CLICK HERE to watch the video.

The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.

Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”

The simple answer is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.

G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.

G1 G7 Ballistic coefficients

Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, believes the G7 standard is preferrable for long-range, low-drag bullets: “Part of the reason there is so much ‘slop’ in advertised BCs is because they’re referenced to the G1 standard which is very speed sensitive. The G7 standard is more appropriate for long range bullets. Here’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:

G1 BCs, averaged between 1500 fps and 3000 fps:
Berger 180 VLD: 0.659 lb/in²
JLK 180: 0.645 lb/in²

The reason the BC for the JLK is less is mostly because the meplat was significantly larger on the particular lot that I tested (0.075″ vs 0.059″; see attached drawings).

For bullets like these, it’s much better to use the G7 standard. The following BCs are referenced to the G7 standard, and are constant for all speeds.

G7 BCs:
Berger 180 VLD: 0.337 lb/in²
JLK 180: 0.330 lb/in²

Many modern ballistics programs, including the free online JBM Ballistics Program, are able to use BCs referenced to G7 standards. When available, these BCs are more appropriate for long range bullets, according to Bryan.

[Editor’s NOTE: BCs are normally reported simply as an 0.XXX number. The lb/in² tag applies to all BCs, but is commonly left off for simplicity.]

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December 23rd, 2021

Amazing Applied Ballistics Rimfire Ammo Test — 50 Types Tested

.22 LR Rimfire Ammunition testing Bryan Litz Applied Ballistics Eley
Photo shows Bryan Litz (on right) and tester Mitchell Fitzpatrick. Bryan said: “Only 2,445 rounds to go! We’re testing over 50 ammo types in five different twist barrels… science can be exhausting!”

Do you know the actual BC (Ballistic Coefficient) of your rimfire ammunition? Well Applied Ballistics has the data, thanks to a comprehensive, marathon ammo testing session. Some years back, in an effort to determine the “real world” BCs of various rimfire ammo types, Bryan Litz and his team at Applied Ballistics did an extraordinary, in-depth shooting test. Litz and company tested over fifty types of .22 LR ammo, using five different twist-rate barrels. This was one of the most comprehensive and through rimfire ammo tests ever done.

.22 LR Rimfire Ammunition testing Bryan Litz Applied Ballistics Eley

.22 LR Rimfire Ammunition testingBryan tolds us: “We tested many types of .22 rimfire ammo for the 2nd Edition of the Ballistic Performance of Rifle Bullets book. We used a pair of Oehler chronographs to measure velocity at the muzzle (MV) and velocity at 100 yards.” With these numbers (average and SD) Bryan can calculate G1 BCs for all the 50+ types of rimfire ammo. What’s more, because every sample is shot through five different barrels (each with a different twist rate) Bryan can also determine how velocity is affected by twist rate.

The tests are primarily to determine velocities for BC calculations — this was not an accuracy test. Bryan explains: “Our tests are not really looking at accuracy, mainly because that’s so subjective to different rifles. Our testing is primarily focused on measuring the BC of rimfire rounds from different twist-rate barrels. The MVs and BCs from the different twist test barrels was then published by Applied Ballistics in print books. Bryan Litz told us: “The .22 LR Rimfire data was originally published in Ballistic Performance of Rifle Bullets, 2nd Edition, which is now out of print. The 3rd Edition of that book doesn’t have rimfire data. The rimfire testing results and data were re-published in Modern Advancements in Long Range Shooting – Volume II (along with many other topics).

Bringing Science to the Rimfire World
Bryan’s goal with this project was to increase the rimfire knowledge base: “We hope to give the world of .22 LR rimfire a good dose of science. How is the BC of .22 rimfire ammo affected by barrel twist? Do subsonic rounds have more consistent BCs than supersonic or transonic rounds? What brands have the highest BCs? What brands have the most consistent MVs?”

.22 LR Rimfire Ammunition testing Bryan Litz Applied Ballistics Eley
Data from two Oehler chronographs is recorded in a computer. Ammo samples were tested in five (5) different barrels (of varying twist rates). Give credit to Dane Hobbs who supplied a test rifle, multiple barrels, and most of the ammo types for the test.

.22 LR at 300 Yards?
Bryan also conducted some longer range rimfire tests. His interesting findings have appeared in the Modern Advancements in Long Range Shooting book series. Bryan notes: “While .22 rimfire isn’t typically considered ‘long range’, we were able to consistently hit a two-MOA steel target at 300 yards with the trajectory predicted by AB software and the measured BC of some standard .22 LR rimfire ammo. The info we’re generating may make it possible to push the range of target engagement for a round that’s not seen much advancement in many decades.”

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October 24th, 2021

Sunday Gunday: Wind-Reading with Keith Glasscock

Keith Glasscock winning wind youtube channel f-Class f-Open wind reading

Keith Glasscock is one of America’s very finest F-Class shooters. This talented trigger-puller took second in F-Open division at the F-Class National Championships three years in a row. A smart engineer with aviation knowledge, Keith is a master wind reader, who has served as the wind coach for top F-Class teams. In fact Keith is in Arizona right now coaching a team at Ben Avery.

Keith shares his wind-reading expertise on his popular YouTube Channel — Winning in the Wind. This channel provides intelligent advice on multiple topics including reloading, load development, shooting strategies, and yes, reading the wind.

Keith has the credentials to back up the advice he offers in his video lessons. A High Master, Keith finished second overall at the 2021 NRA F-Class Long Range Championship in F-Open division. He also finished second at the 2020 Nationals, and he took second place at the 2019 Nationals. His consistency is unrivaled, which means he definitely knows the secrets of long-range wind calling and loading ultra-accurate ammo.

Today we feature two of Keith’s latest YouTube videos, both focused on wind reading.

Wind Direction vs. Wind Speed — Which is More Important

Most shooters find wind reading somewhat intimidating. That is understandable. The wind can change constantly during a match, with variations in both wind velocity and angles. Sometimes you think you have a cycle figured out, but then there can be an unexpected lull. Or you may start a string in what you think is a stable condition, but then a surprise shift changes everything. In addition, wind flows can be influenced by terrain features, such as berms, which have varying effects depending on wind angle (e.g. a tailwind hitting a berm will act differently than a 90-deg crosswind). That is why a good wind reader needs to identify both the wind speed AND the wind angle. In this video, Keith explains when to focus primarily on direction and when to pay most attention to velocity. With headwinds and tailwinds, Keith notes, you should monitor angle changes carefully. With crosswinds, speed is the key variable to watch.

KEY Points to Remember
— Small changes in wind direction changes alter POI drastically at long range
— During head or tailwinds, focus on wind direction
— During crosswinds, focus more on wind speed
— The wind is cyclic — always be aware of the pattern

Keith Glasscock wind reading video winnning spotting scope flag angle kestrel

Determining Wind Direction with Precision

Keith Glasscock winning wind youtube channel f-Class f-Open ES SD loading

Many shooters try to read the wind merely using whatever wind flags might be aloft on the range. Flags are important of course, but there are other vital factors that a wise wind-watcher will monitor. You want to watch mirage, and the movement of grass and trees. In looking for angle changes, Keith says the spotting scope is a very important tool. His tripod is equipped with angle markings on the rotating tripod head. This allows him to ascertain wind angles with great precision.

In the video below, Keith shows how to use a spotting scope to read the wind. He explains how he uses his spotting scope in his role as a wind coach. But a spotting scope can also be used effectively by competitors shooting prone or from a bench. Many top shooters use their spotting scopes to watch mirage during their relays. Keith notes that smart competitors can also use their spotters BETWEEN relays to scout natural wind indicators (moving grass, trees etc.), check for boils, watch mirage, and estimate wind velocity cycles.

KEY Points to Remember
— Wind flags leave a lot to be desired in precision wind direction reading
— Precision wind direction can be obtained with a spotting scope
— There is a boil both directly upwind and directly downwind
— Angle indicator on your tripod helps with angular precision in wind readings
— Scouting with a spotting scope before your turn to shoot can be fruitful

Keith Glasscock winning wind youtube channel f-Class f-Open ES SD loading

Questions and Answers with Keith Glasscock

Keith Glasscock winning wind youtube channel f-Class f-Open wind reading

Q. How did you get started as a wind coach, and what were the most important stages in your progress in wind-reading?

Keith: I started coaching this team in 2017. I was looking for a team to shoot on, but they needed a wind coach. I’ve been a backseat driver ever since. I learned the most about reading the wind from shooting when the conditions are absolutely miserable – flags popping, wind switching, people missing the targets entirely, and there I was, having to make the big call. I learn from my own mistakes, and it shows. I still make mistakes, but try to limit them to ones I haven’t already made. In essence, I am in the most important stage now. Humbly looking at the wind knowing its power and mystery, while learning new things every day.

Q. What are the most common wind-reading mistakes you see people make at matches?

Keith: The most common, in a word, is UNDER-confidence. Most shooters can make that wind call with accuracy. But their fear prevents them from doing that, and prevents them from learning or taking advantage of smooth, solid conditions. The second common mistake is failure to anticipate changes. That comes from not gauging the wind pattern. It’s all about patterns in a sport where wind changes so small have such profound impacts on score.

Q. What’s more important — wind flags, or mirage (or maybe the unexpected horizontal that appears on the last shot recorded on target).

Keith: Both flags and mirage lie. The only thing that tells the truth is a bullet. Unfortunately, the wind can switch faster than you can shoot in most cases. I take a fluid approach. I look for what on the range right now tells me what the wind is doing.

Q. When are conditions so bad/unpredictable that it is necessary to just stop shooting and wait for things to get better?

Keith: This is situational, and comes down to what you are observing. I never like to shoot in the top of a gust condition, even when I know what the hold is. The drop off is what gets you that surprise 8.

Q: What type of wind meters do you recommend?

Keith: While Kestrels are inexpensive and quite serviceable, they are directional in nature. If I want absolute wind speed, an omnidirectional style unit is preferred.

Q. Are there ways to practice reading the wind (and judging wind speeds) when one is away from the range?

Keith: I really concentrate on seeing mirage any time I’m outside, without optics. I can, many times, see the boil of the mirage, and wind direction with the naked eye. My time in aviation has my eye tuned to see things like shear zones and venturis in the airflow. I take a moment, anytime the air is moving, to feel the air on my skin, see the trees and grass moving, and areas where the wind does funny things. Trees and grass tend to get too much credit as precision wind indicators. I use them as wind change indicators. It also gives me an opportunity to humble myself and realize how dependent I am on mirage and flags.

Keith Glasscock winning wind youtube channel f-Class f-Open ES SD loading

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October 19th, 2021

How Altitude Affects Bullet Ballistics (Drag and Drop)

altitude ballistics zeiss LRP S5 318-50 FFP scope
Photo shows the new ZEISS LRP S5 318-50 first focal plane (FFP) scope.

“A bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.”

It’s hunting season, and a good friend is heading to the high country of Colorado next week to pursue elk. He recently zeroed his rifle in California, at a range just a few hundred feet Above Mean Sea Level (AMSL). He wondered if the higher altitude in Colorado could alter his ballistics. The answer is a definite yes. However the good news is that free ballistics calculators can help you plot reliable drop charts for various shooting locations, high or low.

Suunto AltimeterThe question has been posed: “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, at higher altitudes, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ AMSL (Above Mean Sea Level) or less. I’ll need about 29-30 MOA to get from 100 yards to 1000 yards with a Berger 155gr VLD at 2960 fps. By contrast, in Raton, NM, located at 6600′ AMSL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect. It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet AMSL), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

To learn more about all aspects of Exterior Ballistics, Hornady has a useful discussion of External Ballistics including the effects of altitude and temperature. To dig deeper, Sierra Bullets has a comprehensive Exterior Ballistics Resource Page with multiple sections from the Sierra Manual (4th and 5th Editions), including:

Section 3.0: Exterior Ballistic Effects on Bullet Flight
Section 3.1: Effects of Altitude and Atmospheric Conditions
Section 3.2: Effects of Wind
Section 3.3: Effects of Shooting Uphill or Downhill

Example from Section 3.0: “When a bullet flies through the air, two types of forces act on the bullet to determine its path (trajectory) through the air. The first is gravitational force; the other is aerodynamics. Several kinds of aerodynamic forces act on a bullet: drag, lift, side forces, Magnus force, spin damping force, pitch damping force, and Magnus cross force. The most important of these aerodynamic forces is drag. All the others are very small in comparison when the bullet is spin-stabilized.”

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July 6th, 2021

Advice for Long-Range Shooters — Six Tips from Bryan Litz

NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Berger SW Nationals Bryan LitzThe 2021 NRA F-Class National Championships at Camp Atterbury, Indiana kick off soon. The Mid-Range F-Class Nationals run July 22-26, 2021, while the Long Range F-Class Nationals take place July 27-30, 2021. SEE Nat’l Matches INFO Handout.

For those headed to the Nationals, we are sharing some smart tips from a past F-Class Champion who is both a great shooter AND a ballistics wizard. In 2015, Bryan Litz won the F-TR Mid-Range AND Long-Range National Championships hosted at Ben Avery. And at the 2014 Berger SW Nationals (SWN), Bryan took top honors among all sling shooters. If you only know Bryan Litz from his Applied Ballistics Books and DVDs, you may not realize that this guy is a also great marksman along with being an actual rocket scientist!

Given his impressive track record in both F-Class and Palma (Fullbore) out to 1000 yards, we asked Bryan if he had any advice for other long-range competitors.

First Bryan provided three tips concerning Ballistics, his special area of expertise. Next Bryan offered three more general tips about long-range competition — how to analyze your shooting, how to choose your ‘wind strategy’, and how to avoid the most costly mistakes, i.e. how to avoid the “train-wrecks”.

Bryan Litz won the 2015 F-TR Mid-Range and Long-Range Championships with this sleek rig:
NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Litz Ballistics Tips

Ballistics TIP ONE. If you’re having trouble getting your ballistic software to match actual drops, you need to look at a number of possible reasons. Here are some common issues that can cause problems.

Click Values Are Not Exact. Scopes and iron sights don’t always produce accurate adjustments. In other words, if your ballistics program predicts 30 MOA of drop, and you dial 30 MOA but hit low, it might be that your sight actually only moved 28 MOA (for example). To see if your sight is adjusting accurately, shoot a tall target at 100 yards and measure group separation when dialing your sight.

Barometric vs. Station Pressure. This is a commonly misunderstood input to ballistics programs. You can avoid this pitfall by remembering the following: station pressure is the actual measured pressure at your location, and you don’t need to tell the program your altitude when using station pressure. Barometric pressure is corrected for sea level. If you’re using barometric pressure, you also have to input your altitude.

Muzzle Velocity. Chronographs are not always as accurate as shooters think they are — your true MV may be off by 10-20 fps (or more). If your drop is different than predicted at long range, it might be because your muzzle velocity input is wrong.

Mixing Up BC (G1 vs. G7). Knowledgeable long range shooters know that the G7 standard is a more representative standard for modern LR bullets. However, using G7 BCs isn’t just a matter of clicking the ‘G7′ option in the program. The numeric value of the BC is different for G1 and G7. For example, the G1 BC of the Berger 155.5 grain Fullbore bullet is .464 but the G7 BC is .237. If you were to enter .464 but click on G7, the results would be way off.

Ballistics TIP TWO. A properly installed level is absolutely essential for long range shooting. Without a good level reference, your long range wind zero will be off due to minor canting of the rifle from side to side. You can verify that your level is installed correctly on a 100-yard ‘tall target’. Draw a plumb line straight up the target and verify that your groups track straight up this line as you go up in elevation.

Ballistics TIP THREE. If your long range ballistic predictions aren’t tracking, always come back and verify your 100-yard zero. Sometimes a simple zero shift can be misconstrued as errors in long range ballistics predictions.

Berger Southwest SW SWN Nationals Ben Avery Bryan Litz
Bryan Litz Tips

Litz Competition Shooting Tips

Competition TIP ONE. Improving your scores in long range competition is a constant process of self-assessment. After each match, carefully analyze how you lost points and make a plan to improve. Beginning shooters will lose a lot of points to fundamental things like sight alignment and trigger control. Veteran shooters will lose far fewer points to a smaller list of mistakes. At every step along the way, always ask yourself why you’re losing points and address the issues. Sometimes the weak links that you need to work on aren’t your favorite thing to do, and success will take work in these areas as well.

Competition TIP TWO. Select your wind shooting strategy carefully. For beginners and veterans, most points are typically lost to wind. Successful shooters put a lot of thought into their approach to wind shooting. Sometimes it’s best to shoot fast and minimize the changes you’ll have to navigate. Other times it’s best to wait out a condition which may take several minutes. Develop a comfortable rest position so you have an easier time waiting when you should be waiting.

Competition TIP THREE. Actively avoid major train wrecks. Sounds obvious but it happens a lot. Select equipment that is reliable, get comfortable with it and have back-ups for important things. Don’t load on the verge of max pressure, don’t go to an important match with a barrel that’s near shot out, physically check tightness of all important screws prior to shooting each string. Observe what train wrecks you and others experience, and put measures in place to avoid them.

NRA F-Class F-TR F-Open Nationals National Championships Bryan Litz

Photos by Steve Fiorenzo

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June 22nd, 2021

Sectional Density of Bullets — What You Need to Know

Bullet projectile sectional density formula Sierra Bullets

by Sierra Bullets Ballistic Technician Paul Box
All of us who have been in reloading and shooting for any period of time have read how sectional density has been regarded as a bullet’s ability to penetrate. Back before high velocity came along and modern bullet design, the easiest way to get more “power” and penetration was by increasing the diameter and mass. After all, a bowling ball will hurt more than a golf ball, right?

Let’s take a closer look at sectional density.

The formula for calculating sectional density is pretty simple and straight forward. Take the bullet weight and divide by 7000. This number is then divided by the bullet diameter squared. Two bullets of equal weight and the same diameter will have equal sectional sectional density. No regard is given to the bullet construction. This is where the fly hits the soup in considering sectional density as far as penetration is concerned.

Section Density Formula: (Bullet Weight divided by 7000) divided by Bullet Diameter squared.

Bullet construction is the biggest factor in how it is able to penetrate. The best example I can think of here is to look at the Sierra .224 55 Gr. FMJBT GameKing #1355 compared to the 55 Gr. BlitzKing #1455. Both are .224 and weigh 55 grs. Both have a sectional density of .157. But there is a huge difference in their construction. The FMJ has a thick jacket and is designed to penetrate. The BlitzKing is designed for fast and rapid expansion with little concern for how deep they will penetrate.

The next time you’re choosing a bullet, look at the construction and less at the sectional density number. It’s all about the construction anyway. If you have any questions or would like to discuss sectional density or bullet penetration further, please give us a call at 800-223-8799 or shoot us an email at sierra@sierrabullets.com.

Sierra Bullets reloading tips

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June 2nd, 2021

Get FREE Lapua 6DOF Ballistics App for Android and iOS

Lapua ballistics app android apple free

Download the FREE Lapua Ballistics App

Lapua now offers a FREE Ballistics App. This was the first mobile ballistics App utilizing the 6DOF calculation model, making it one of most accurate ballistics Apps on the market. With this free mobile App you can calculate trajectories, range, bullet drop, turret adjustments and more.

Lapua Ballistics App 6DOF degrees of Freedom solver doppler radar bullet BC Apple iOS Android OS mobile smartphone iphone

Lapua’s sophisticated FREE Ballistics App has many great features — much more than you’d expect for a free App. If you do much shooting past 300 yards, or use a wide variety of bullets and/or cartridge types, definitely download the App and give it a try. For more details, read the Lapua Ballistics App User Manual. This handy PDF file explains how to set up the App and utilize all its powerful features.

CLICK HERE for FREE 29-page Lapua Ballistics App USER GUIDE

The Lapua Ballistics App is available for Android and iOS smart phones and mobile devices free of charge. For more info, visit www.lapua.com/resources/lapua-ballistics-app.

Features in the Lapua Ballistics Calculator

  • Utilizes 6DOF, the most accurate calculation method
  • Always available with latest Lapua cartridge / bullet information
  • Quick and easy to change inputs like distance, wind speed and angle
  • Several result outputs available, with numerical, reticle, table and graph views
  • Create and clone your own firearm / reticle combinations
  • Choose between metric and imperial values
  • Set Point Blank-range to different sight-in distances and impact windows
  • Set Aiming point to moving target
  • Add custom bullets (calculations based on BC G1 or G7 and Siacci method)
  • Features include Sight-in-POI, Coriolis, Max Range and Cant Angle calculation
  • Compare up to 3 Lapua cartridge/bullet performances to each other
  • Custom trajectory tables

Lapua ballistics app android apple free

After downloading the FREE Lapua Ballistics App for Android device or Apple iPhone/iPad, you’ll want to access the Lapua Ballistics App Guide which shows how to use all the features and options. In addition, Lapua offers a handy FAQ Page with User Tips and Answers to frequently Asked Questions.

Watch Video for Explanation of Lapua Ballistics App Features

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April 18th, 2021

Are You a Gun Wizard? Take the Shoot 101 Ballistics Quiz

Shoot 101 Ballistics Question Quiz BC trajectory

Shoot 101 Quiz
How much of an expert are you when it comes to firearms and ballistics? Test your knowledge with this interactive test. Vista Outdoor, parent of CCI, Federal, Bushnell, RCBS and other brands, has a media campaign called Shoot 101, which provides “how to” information about shooting, optics, and outdoor gear. There were a variety of interactive offerings that let you test your knowledge.

On the Shoot 101 website, you’ll find a Ballistics Quiz. The questions are pretty basic, but it’s still fun to see if you get all the answers correct.

You don’t need a lot of technical knowledge. Roughly a third of the questions are about projectile types and bullet construction. Note, on some platforms the layout doesn’t show all FOUR possible answers. So, for each question, be sure to scroll down to see all FOUR choices. REPEAT: Scroll down to see ALL answers!

CLICK HERE to Go to SHOOT 101 Ballistics QUIZ Page »

Sample Ballistics Question 1:

Shoot 101 Ballistics Question Quiz BC trajectory

Sample Ballistics Question 2:

Shoot 101 Ballistics Question Quiz BC trajectory

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April 13th, 2021

Tuesday Trivia: Can You Over-Stabilize a Bullet?

spinning bullet stabilizationOn the Applied Ballistics Facebook page a few seasons ago, Ballistician Bryan Litz posed a “Tuesday Trivia” question about ballistics. This being Tuesday we thought we’d bring back this interesting brain-teaser — a true/false question about bullet stabilization. On shooting forums you often find heated arguments about “over-stabilization”. Bryan wants readers to consider the issue of over-stabilization and answer a challenge question…

Is This Statement TRUE or FALSE?

“The problem with ‘over-stabilizing’ a bullet (by shooting it from an excessively fast twist rate) is that the bullet will fly ‘nose high’ on a long range shot. The nose-high orientation induces extra drag and reduces the effective BC of the bullet.”

True or False, and WHY?

Click the “Post Comment” link below to post your reply (and explain your reasoning).

Bullet Movement in Flight — More Complicated Than You May Think
Bullets do not follow a laser beam-like, perfectly straight line to the target, nor does the nose of the bullet always point exactly at the point of aim. Multiple forces are in effect that may cause the bullet to yaw (rotate side to side around its axis), tilt nose-up (pitch), or precess (like a spinning top) in flight. These effects (in exaggerated form) are shown below:

spinning bullet stabilization

Yaw refers to movement of the nose of the bullet away from the line of flight. Precession is a change in the orientation of the rotational axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle (nutation) is constant. In physics, there are two types of precession: torque-free and torque-induced. Nutation refers to small circular movement at the bullet tip.

Diagram from the University of Utah Health Sciences Library Firearm Ballistics Tutorial
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