October 19th, 2014

How Altitude and Air Pressure Influence Ballistics

Suunto AltimeterOne of our readers asked “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, 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′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, 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 Kestral, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 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.

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

if you want to learn more about all aspects of External Ballistics, ExteriorBallistics.com provides a variety of useful resources. In particular, on that site, Section 3.1 of the Sierra Manual is reprinted, covering Effects of Altitude and Atmospheric Pressure on bullet flight.

Permalink Tech Tip 5 Comments »
October 2nd, 2014

World’s Most Expensive Scope? $12K Hensoldt 6-24x72mm SAM

When does a scope cost as much as a new Harley-Davidson? When it is a top-of-the-line 72mm Hensoldt (by Zeiss). The remarkable Hensoldt ZF 6-24x72mm SAM scope integrates ultra-bright apochromatic fluorite glass with a calculator module that provides ballistic info and weather data to the shooter. This 6-24x72mm SAM Hensoldt may be the most advanced riflescope on the planet. With a street price of $11,982.00, it is certainly one of the most expensive. Take a 360° tour with this cool video from Hensoldt Zeiss.

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Hensoldt ZF 6-24x72mm SAM
SAM stands for “Sniper Auxiliary Module”. An integrated ballistics calculator can be programmed for up to four different types of ammo. Sensors in the integrated ring mount measure weather parameters. These values, as well as scope data, are then directly projected into the visual field of the eyepiece. This provides selectable displays of elevation clicks, windage clicks, angle of fire, cant angle, temperature, and air pressure.

Hensoldt Zeiss

Hensoldt Zeiss

Hensoldt Zeiss

Permalink Gear Review, Optics 6 Comments »
October 1st, 2014

Long Range Shooting Made Easy (New Video)

Accuracy 1st Development Group, a training operation based in Texas, will soon release a new instructional video: Long Range Made Easy. This training video features Bryan Litz, author of Applied Ballistics for Long Range Shooting. Many of the shooters shown in the video use the new ABM ammo developed by Bryan’s Applied Ballistics lab for Berger Bullets. Check out the preview “trailer” for Long Range Made Easy.

Watch Trailer for “Long Range Made Easy”

Accuracy 1st Development Group

Accuracy 1st Development Group

Accuracy 1st Scope Levels
Accuracy 1st also sells some interesting products for precision rifle shooters. Check out this unique, curved-vial scope leveler ring. More precise and sensitive than other scope levels, the Accuracy 1st leveling device can detect 1° of cant. Displayed line increments represent 2.5° of cant.

Scope Level – Tan Matte Teflon
Including 30mm Reducer Ring
Scope Level – Black Anodized Aluminum
34 Ring Size
Scope Lever Ring Accuracy 1st Scope Lever Ring Accuracy 1st

You may wonder: “Why are these scope levels better than other similar products?” Accuracy 1st explains: “Our levels are of the highest quality and accuracy. Some scope level manufacturers use plastic housings, air bubbles and sub-par glass in their vials. In lieu of a straight bubble vial, Accuracy 1st utilizes a custom curved vial featuring medical-grade glass and a ceramic ball. The use of the ceramic ball eliminates the inherent flaws associated with air bubble levels, which at higher temperatures and pressure will compromise the bubble size causing level inaccuracies. Typically air bubble levels require 3° to 5° [tilt] to even register movement. By contrast, the Accuracy 1st custom level will read movement at a minimum of 1° and will extend measurements out to +/- 10°.”

Permalink - Videos, Shooting Skills 3 Comments »
September 26th, 2014

Norma’s “Ammo Academy” Provides Valuable Information

If you haven’t visited the Norma website recently, you should click over to www.norma.cc/en/ (the ‘en’ is for English version). There you will find Norma’s “Ammo Academy”, a technical resource that provides information on: Ballistics, Powder Storage, Barrel Wear, and Bullet Expansion. In addition, the Ammo Academy now links to Norma’s Reloading Data Center, where you’ll find loads for nearly 70 cartridge types including: .223 Rem, .22-250, 6mmBR Norma, 6XC, 260 Rem, 6.5-284, 6.5×55, 7mm-08, .270 Win, .284 Win, .308 Win, .30-06, 300 Win Mag, .338 Lapua Mag and dozens more.

Norma web site Ammo Academy

The Ammo Academy’s Ballistics section contains some fascinating technical facts:

stopwatch

  • After the trigger is pulled, it takes around 0.005 seconds before the firing pin reaches the primer.
  • From the firing of the primer it takes 0.0015-0.002 seconds until the bullet exits the muzzle.
  • When the bullet leaves the muzzle, the hot gases surround and overtake the bullet, continuing the acceleration for a few centimeters.
  • Because the barrel is always angled slightly upwards, the bullet’s flight starts about 3-5 cm below the line of sight.

Norma also offers some good advice about Powder and Cartridge Storage:

To maintain the product quality for as long as possible, you have to keep the powder in a suitable place under suitable conditions. Where possible, store the powder at a constant temperature, ideally between 12 and 15°C (54°F to 59°F), and a relative humidity of 40–50%. If the air is too dry, it will dry out the powder, which will cause the pressure to be higher, thus affecting performance. Also make sure that you close the powder container properly afterwards. Cartridges should be stored under the same ambient conditions to maintain their quality.

For more info on Norma products, CLICK HERE to access Norma’s Catalog Download Page.

Story Tip by EdLongrange. We welcome submissions from our readers.
Permalink Bullets, Brass, Ammo, Reloading No Comments »
August 9th, 2014

“Firearm Science” Video Shows the Process of Zeroing Rifle

Most of us can figure out how to zero our rifles at 100 yards. But do you know how to get a solid zero at long range — as far as 1000 yards? You need to know your ballistics, otherwise you may waste a lot of ammo “sprayin’ and prayin’”. You definitely need to know your exact muzzle velocity, within a few FPS. This is not as simple as it seems, because it is not uncommon for chronograph results to be off by 10 to 20 fps or more, just through calibration error. Accordingly, you may want to test with a pair of chronos and record the results from each (you may be surprised at the variances).

scope turret elevation nightforceVideo Illustrates Zeroing Process
The process of zeroing rifles for long range is covered in a new “Firearm Science” video from the NRA. This video features George Reinas, a popular competitor on the Top Shot TV Show. George demonstrates how to adjust his scope to compensate for bullet drop at long range. Our friend Dennis Santiago was involved in the making of this video, which was filmed at the Burbank Rifle & Revolver Club in Southern California. The video is narrated by the talented Jessie Duff, one of America’s best action shooters.

scope turret elevation nightforceWhen zeroing at long range, you should first consult a good ballistics program. Select your baseline zero distance (such as 100 yards), then plug in the MV along with salient environmental factors: Altitude, Air Pressure, Temperature, Humidity. After you enter bullet BC, your ballistics program will calculate the drop to the target, expressed in MOA or Mils. Some programs will actually list the number of clicks up from your current zero.

You can print out the data from your ballistics solver as a “drop chart” that can be attached to your rifle stock. If you shoot at various altitudes you may need multiple drop charts.

Permalink - Videos, Shooting Skills 6 Comments »
July 22nd, 2014

Zeiss Ballistics Calculator Mobile App for Android and iOS

Zeiss mobile ballistics appCarl Zeiss Sports Optics (Zeiss) has a new mobile Ballistics Calculator App for iOS (Apple) and target="_blank">Android devices. Modeled after the web-based Zeiss Ballistics Calulator, the new Mobile App is tailored to work precisely with Zeiss Ballistic reticles. Mike Jensen of Carl Zeiss Sports Optics explained: “We wanted those who use our proprietary ballistic reticles to have a ballistic tool that could be used virtually anywhere you have a signal for your device.”

The Zeiss Ballistic Calculator App allows users to pick their ballistic reticle from a drop-down menu. The user also has the ability to select factory or hand load data as well as environmental variables, and then the system will calculate and display the optimum magnification setting. With this system, distant yardages now coincide with the Zeiss ballistic reticle subtensions. The system allows the user to adjust standard settings for altitude and temperature, as well as other advanced settings, e.g. for muzzle velocity and sight height above bore.

Zeiss Ballistics Calculator App Features:

- One page screen application for fast data entry and easy to read results.

- Comprehensive and current database for factory and hand-loaded ammunition.

- Adjustable settings to customize unique shooting environments.

- Slide feature to visualize how magnification change alters point of impact.

Zeiss mobile ballistics app

The Zeiss Mobile Ballistic Calculator App can be downloaded at target="_blank">Google Play (Android App) and iTunes (iPhone App) for $4.99. Zeiss has noted that the App will soon be updated to include the Zeiss ASV ballistic turret system.

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June 26th, 2014

Modern Advancements in Long Range Shooting — By Bryan Litz

Litz Applied Ballistics Book Modern Advancements Long Range ShootingApplied Ballistics, LLC is offering an all-new book by Bryan Litz, the first in a series. The new 339-page, hard-cover book, Modern Advancements for Long Range Shooting, Volume I, documents the ongoing R & D being done at the Applied Ballistics laboratory, the “Area 51″ of the shooting world.

“This new series is heavily based in experimental ballistics, and takes a ‘Myth Busters’-type approach to many of the questions and problems faced by modern long range shooters,” stated Litz. Volume I of the series is scheduled for release in late July, 2014. The book will cost $39.95, but you can pre-order now for $35.95, a 10% savings.

Bryan adds: “Anyone interested in the underlying science behind shooting can benefit from this book. We address the important questions… How much does faster twist affect MV? How does stability affect BC from the muzzle and downrange? What chronographs are capable of high accuracy and precision? What characteristics should you look for in your long range rifle and optic set up? What new gadgets are being developed to enhance long range shooting?

New Book Features Extensive Live-Fire Test Results
Bryan tells us: “The book spotlights state-of-the-art technologies (and methodologies) in long range shooting. New equipment and old ideas are explored using experimental, live-fire testing. Extensive test results are reported in an easy-to-understand way. Among other things, our tests explore the effects of twist rate on muzzle velocity, BC (supersonic and transonic), precision, even spin rate decay for various rifling profiles as they are tested experimentally.

Chronographs and Optics Are Tested and Compared
Litz’s new book traces the evolution of modern rifle, bullet, and optic design. Results from chronograph comparison tests are presented, showing the strengths and weaknesses of available commercial chronographs. High-tech instrumentation such as laser rangefinders and wind measurement devices are explained in detail by contributing author Nick Vitalbo.

The New Book Puts Theory into Practice
We asked Bryan Litz how this new book differs from his previous treatises. Bryan replied: “My original Applied Ballistics for Long-Range Shooting book explains the fundamental elements of external ballistics. It’s the academic background which all future work relies on. The new book, Modern Advancements in Long Range Shooting, covers the ongoing development of equipment and ideas. We explore things like twist rate effects, modern rifle and optic design, and some of the high tech instruments which are being used to enhance the effectiveness of long range shooting.

Litz Applied Ballistics Book Modern Advancements Long Range Shooting

Permalink Bullets, Brass, Ammo, New Product 1 Comment »
June 13th, 2014

"How Do Bullets Fly?" — Great Online Resource

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.

Bullet External Ballistics

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 to download “How Do Bullets Fly” complete text. (1.2 MB .zip file)

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

Permalink - Articles, Bullets, Brass, Ammo 1 Comment »
June 9th, 2014

NEW eBook Version of Applied Ballistics for Long-Range Shooting

eBook Applied Ballistics long range shooting bryan litzBallistics books have gone digital. Bryan Litz’s Applied Ballistics For Long-Range Shooting (2nd Edition), the leading treatise on the subject, is now available in digital eBook format. This new eBook version contains all the text of the print version, all the charts, all the diagrams, and all the photos. You get all this in an easy-to-read, easy-to-search format that can be viewed on a variety of devices*. You can access the book on your home computer, on your laptop, on a tablet, on a smartphone, or on a lightweight, portable Kindle e-Reader. And yes, iPad users can use the Kindle app to read the book on an iPad.

CLICK for FREE Sample of Applied Ballistics
for Long-Range Shooting (2d Ed.) eBook

NOTE: After clicking this link to go to Amazon.com, click on the blue book image labeled “Look Inside”. This will launch a preview window. Alternatively, Kindle users can click the “Send Sample Now” button.

Advantages of the eBook Edition
The eBook release of Bryan Litz’s most popular and comprehensive ballistics book is a big deal, in our opinion. There are many advantages to the digital format. First you can quickly search for any term or reference, or click from table of content entries to desired chapters. Second, you can highlight text and bookmark pages for future review. Third, you can easily change the font size to enhance reading for older eyes. Fourth, you can zoom in the charts, diagrams, and photos for a better view. Last but not least, you can easily carry the entire text in the field on the same digital device that holds your ballistics solver software.

The new eBook version of Applied Ballistics for Long-Range Shooting (2d. Ed.) is available now on Amazon.com for $39.95.

Highlights of eBook Edition
The eBook version of Applied Ballistics for Long-Range Shooting (2d Ed.) is available now on Amazon.com. Since its release in 2011, the second edition (hardcopy) of Applied Ballistics for Long Range Shooting has sold over 10,000 copies. It’s the modern ‘go to’ book on the subject of ballistics for long range shooters. The Second Edition of the book includes two additional chapters covering extended long-range shooting and monolithic bullets.

200 Bullet Types Tested. In this eBook edition, Bryan Litz includes data from his own personal field tests with over 200 bullet types. Performance data (G1 and G7 BCs confirmed by live-fire testing) is presented along with 2-D drawings for hundreds of long range bullets.

Ballistic Program Included. eBook buyers can receive the Point Mass Ballistics Solver 2.0 for no extra charge. The software comes on a CD with the hardcopy. With the eBook, there are two ways to access the ballistics program. First, you can access the free AB online ballistics solver through embedded links in the eBook and run directly from your eReader. Alternatively, you can request the PM Solver program to be emailed to you for running on a PC.

“Our mission at Applied Ballistics is to be the complete and unbiased source of external ballistics information for long range shooters,” stated Bryan Litz, author and owner of Applied Ballistics, LLC. “We’re constantly testing new claims, products and ideas and dispensing the marketing hype which can make it difficult for shooters to master the challenging discipline of long range shooting. We developed the original hard copy of the book in order to provide shooters of all capabilities with this knowledge. The release of the eBook will not only provide readers with the same knowledge, but do so in a more accessible and mobile way.”

Sample Page from eBook
eBook Applied Ballistics long range shooting bryan litz

* Installation of FREE eReader software may be required for viewing on desktop computers, laptops, tablets, and smartphones. This only takes a minute or so.

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June 5th, 2014

Windmeter with Rotating Head Shows 90° Crosswind Values

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.

Caldwell crosswind wind meter

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:

Caldwell crosswind wind meter

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.

Caldwell crosswind wind meter

Permalink Gear Review, New Product 2 Comments »
May 12th, 2014

Print Handy Drop-Chart with FREE Hornady Ballistics Calculator

Hornady Ballistics CalculatorNeed a simple, easy-to-use drop chart for your rifle? Something you can tape right to the buttstock? Then check out Hornady’s handy Online Ballistics Calculator. This user-friendly calculator will compute your drops accurately, and output a handy “Cheat Sheet” you can print and attach to your rifle. Simply input G1 or G7 BC values, muzzle velocity, bullet weight, zero range and a few other variables. Click “Calculate” and you’re good to go. You can select the basic version, or an advanced version with more data fields for environmental variables (altitude, temperature, air pressure, and humidity). You can also get wind drift numbers by inputing wind speed and angle.

Hornady Ballistics Calculator

Conveniently, on the trajectory output, come-ups are listed in both MOA and Mils — so this will work with either MOA clicks or Mil-based clicks. There are more sophisticated ballistics solvers available on the web (such as the outstanding Applied Ballistics Online Calculator), but the Hornady Calculator is very simple and easy to use. If you just want a basic drop chart, you may want to check this out.

Hornady Ballistics Calculator

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April 13th, 2014

Field Skills: Reading the Wind When Hunting

On LongRangeHunting.com, you’ll find a good article by Shawn Carlock about wind reading. Shawn is a veteran law enforcement marksman and a past USPSA national precision rifle champion. Shawn offers good advice on how to estimate wind speeds and directions using a multitude of available indicators — not just your wind gauge: “Use anything at your disposal to accurately estimate the wind’s velocity. I keep and use a Kestrel for reading conditions….The Kestrel is very accurate but will only tell you what the conditions are where you are standing. I practice by looking at grass, brush, trees, dust, wind flags, mirage, rain, fog and anything else that will give me info on velocity and then estimate the speed.”

Shawn also explains how terrain features can cause vertical wind effects. A hunter on a hilltop must account for bullet rise if there is a headwind blowing up the slope. Many shooters consider wind in only one plane — the horizontal. In fact wind has vertical components, both up and down. If you have piloted a small aircraft you know how important vertical wind vectors can be. Match shooters will also experience vertical rise when there is a strong tailwind blowing over an up-sloping berm ahead of the target emplacements. Overall, Shawn concludes: “The more time you spend studying the wind and its effect over varying terrain the more successful you will be as a long-range shooter and hunter.”

Permalink - Articles, Hunting/Varminting, Shooting Skills 1 Comment »