December 16th, 2018

G1 vs. G7 Ballistic Coefficient Models — What You Need to Know

G1 G7 BC drag models

Over the past 12 months, this article was one of the TOP TEN 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 preferrable 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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September 7th, 2017

How to Use Lapua’s Advanced FREE Ballistics App

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

Lapua offers a sophisticated FREE Ballistics App for iOS and Android smartphones and mobile devices. This state-of-the-art 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, we recommend you download the App and give it a try. This article, written by a Lapua technician, explains how to use the App. This article is definitely worth reading — there are many important concepts and procedures discussed here that apply to all Ballistics calculators, not just the Lapua App. For more details, read the Lapua Ballistics App User Manual.

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/lapuaballisticsapp.

Lapua Ballistics App Basics — How to Get Started

Lapua bullets trajectory 6DOF Ballistics App Hunting G1 G7

Article by Matti Paananen
As smartphones and tablets are constantly developed, ballistic software and Apps are also improving, and with their help our ability to hit targets can improve significantly. This is a short introduction on why and how to use a ballistic calculator, namely the Lapua Ballistics App, and a few pointers that will help you use the App effectively.

CLICK HERE for FREE 28-page Lapua Ballistics App USER GUIDE

Ballistics software and Apps are designed to help shooters and hunters make calculations to hit distant targets or take down game in the field by offering ballistic solutions. Lapua Ballistics is the first App utilizing the 6DOF calculation model.

Toying around with ballistics apps is always fun, but effective use of ballistic software requires general understanding of how they work. The App gets information from the user and by using mathematical formulas it provides the solution that will give the user a solid starting point to hit the target.

However, it is also important to remember that the App can’t think — it only calculates a solution based on your parameters. You will not know the error until you have already fired the shot.

1. SET UP YOUR SCOPE RETICLE AND RIFLE
Scope manufactures use different units per click, so it’s important that you use the correct unit in the App. For example, in your scope, one click can be 0.1 mil, 1/4 MOA, [or 1/8 MOA depending on the model]. You can find this information in your scope manual and also usually from the scope turrets. Setting your scope reticle is very important, partly because if you use the wrong unit in the App, the ballistic solution will not match your scope. To set up your scope reticle in Lapua Ballistics, go to Manage Rifle / Cartridge Data –> Add Rifle Cartridge Data (or choose to edit a Rifle/Cartridge combo you’ve already set up) –> Reticle –>.

Lapua 6DOF Ballistics App Hunting G1 G7

Another thing to setup in Lapua Ballistics is your scope height, i.e. Line of Sight to Bore in the Manage Rifle / Cartridge Data window. This is the distance between the center of the scope and the center of the bore. The default height is 45mm but with tactical rifles, the height can be even 70mm. So check! The height is easy to measure with a ruler. Then there’s also the twist rate of your rifle to set up — look it up in the rifle manual, it can also be stamped on the rifle barrel. The rifle twist rate is needed to calculate spin drift and bullet stability. Spin drift should be taken into account with longer distances, and it can be enabled or disabled in Lapua Ballistics.

2. SET UP YOUR BULLET CHOICE
You can add your bullet of choice from the bullet library, where you find all Lapua bullets. It is also possible to add information manually. In this case, you will need bullet weight, the ballistic coefficient BC and muzzle velocity. The Ballistic coefficient can be given in G1 or G7 values. G7 is designed for low-drag bullets with a boat tail and G1 is used for more traditional flat base bullets. Lapua on the other hand uses Doppler radar-based data to calculate a more accurate ballistic trajectory for Lapua bullets by 6DOF model. Anyway, it is good to remember that the ballistic coefficient changes with velocity, so all changes in a flight path cannot be predicted.

The following thing you will need to set up is the bullet’s actual muzzle velocity. You can reverse engineer the number based on your drop or by using a chronograph. It is good to remember that more rounds you shoot, the better average velocity you will get.

Lapua Bullets 6DOF Ballistics App Hunting G1 G7

Because temperature affects muzzle velocity, it would be good to shoot velocities in different temperatures and write them down. Those notes can be used with Lapua Ballistics as it is possible to set up the powder temperature variation in the App.

3. SET UP WEATHER CONDITIONS
Lapua Ballistics has settings for temperature, air pressure, and humidity. All these affect the ballistic solution and the chance to hit the target. In a nutshell, temperature affects the powder’s burn speed and in that way the bullet velocity. Air pressure and humidity also affect bullet drag.

If you are shooting approximately on sea level, you do not need to change air pressure values, but if you are shooting or hunting in mountain areas or where there is lot of elevation difference, you might want to check the air pressure. On sea level, the atmospheric pressure is 1013 hPa. The higher you go, the less air pressure you will have and thus less bullet drag. Some like to use handheld weather and wind meters that have a function to get actual air pressure and humidity, however the Get Current Weather function in Lapua Ballistics will give you the air pressure reading from your local and most close weather station, provided that your app is allowed to use your location data.

Lapua Bullets 6DOF Ballistics App Hunting G1 G7

Temperature is an important variable. To understand how velocity change in different temperatures, only way is to shoot and keep notes. Some ballistic software and apps have values for muzzle velocity in different temperatures. The user needs to input muzzle velocity in different temperatures in order to software to calculate the effect. More velocities in different temperatures the user adds, the more accurate the calculation will be.

4. SET UP A BALLISTIC SOLUTION
After we have set up our own rifle / cartridge data, there are few things that need to be taken into account when shooting: the distance to the target, the wind and our shooting skills. Distance can be measured for example with a laser rangefinder and then put in. Wind can also be measured with a wind gauge but it is important to remember that the wind in the target area can be very different from that in the shooting position. Lapua Ballistics gives a ballistic solution based on stationary wind, so in the end, the shooter’s task is to estimate how much the wind factor will be.

It’s good to remember that Lapua Ballistics is a starting point and designed to assist the shooter. Software and apps have ways of helping us adjust the sight and predict the ballistic solution but they will not replace the shooter. We still have to pull the trigger and record our range data. By keeping good range notes and with the support of good ballistic software like Lapua Ballistics, we should be able hit in all environments.

Watch Video for Explanation of Lapua Ballistics App Features

Article Find by EdLongrange. We welcome reader submissions
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October 19th, 2016

Lapua Releases FREE Advanced 6DOF Ballistics Mobile APP

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

Lapua, maker of premium brass, bullets, and loaded ammo, has released a new, state-of-the-art Ballistics program that runs on smartphones and mobile devices. The all-new Lapua Ballistics Mobile App is the first mobile ballistics app utilizing the 6DOF calculation model. 6DOF refers to “Six Degrees of Freedom”, referring to the multiple variables the software calculates. As explained below, a 6DOF solver can account for 3 components of movement PLUS 3 components of rotation. Of course, as with other ballistics software, the Lapua Mobile App looks at Bullet BC, velocity, and cross-wind effects. This software can also account for subtle, extreme long range factors such as the Coriolis Effect.

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


CLICK HERE for FREE 28-page Ballistics App USER GUIDE

Notably, the new Lapua Ballistics App includes a library of up-to-date bullet profiles based on extensive field tests with Doppler Radar. Having an ultra-sophisticated 6DOF solver combined with Doppler Radar data makes the Lapua Mobile App one of the most accurate ballistics Apps on the market. Lapua Ballistics offers the latest, Doppler-proven Lapua cartridge and bullet data for you to combine with your firearm and local weather information. The App also includes the option to define custom bullets.

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

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/lapuaballisticsapp.

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

6DOF, the most accurate calculation method. Lapua cartridge / bullet information. Distance, wind speed and angle. outputs numerical, reticle, table and graph views, metric and imperial values. Set Point Blank-range to different sight-in distances and impact windows. Define custom bullets ( BC G1 or G7 and Siacci method), Pre-set max 4 powder temperature.Sight-in-POI, Coriolis calculation

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October 22nd, 2015

Berger Updates Bullet BC Data and Recommended Twist Rates

Berger BC Ballistics Coefficient Barrel Twist Rate  Updates

Berger has released two important informational updates for its line-up of bullets. First, the Ballistics Coefficients (BCs) have been updated for the vast majority of bullets Berger sells. In addition, G7 model BCs are being provided for most of the bullets. You will want to use the updated BC data, which is based on actual testing of recent production lots of bullets.

Second, Berger is now providing a dual twist-rate recommendation for most bullets. Berger is now lists a “minimum” barrel twist rate as well as an “optimal” twist rate. To get maximum long-range performance from your bullets, use a barrel with the “optimal” rate of twist.

CLICK HERE for the latest Berger Quick Reference Sheets with updated BCs and new Optimal Twist Rates. Eric Stecker, Berger President says: “We have tested every lot of bullets‬ produced in the last several years to bring you these updated numbers for all of our bullets.”

Ballistic Coeffificent (BC) Updates with G7 Data
Berger notes: “We have updated all of our Ballistic Coefficients to be even more accurate.
Prior to 2008, all of Berger Bullets’ BCs were calculated using a computer prediction. Early in 2009, we began measuring BCs with live-fire testing. As a result, Berger’s BCs were updated and G7 BCs were also made available. This represented a dramatic improvement in the accuracy of performance data at that time. Since 2009, the BCs assessed for Berger Bullets have not been updated. As part of our ongoing effort to provide shooters with the best information possible, Berger has been testing every lot of bullets produced for the last several years. The result is updated and highly accurate running averages of BCs for recent production lots.

Here are some of the Updated BC Values for popular Berger Target (Match) Bullets:

Description New G1 BC New G7 BC % Change
22 Cal 80gr VLD Target 0.455 0.233 +2%
22 Cal 90gr VLD Target 0.534 0.274 -3%
6mm 95gr VLD Target 0.467 0.240 -3%
6mm 105gr VLD Target 0.517 0.265 +5%
6mm 105gr Hybrid Target 0.536 0.275 -1%
6mm 115gr VLD Target 0.563 0.289 +3%
6.5mm 130gr VLD Target 0.562 0.288 +2%
6.5mm 140gr Hybrid Target 0.607 0.311 -2%
7mm 180gr VLD Target 0.683 0.350 +4%
7mm 180gr Hybrid Target 0.680 0.349 +1%
30 Cal 155gr Hybrid Target 0.478 0.245 -1%
30 Cal 185gr Hybrid Target 0.576 0.295 +1%
30 Cal 215gr Hybrid Target 0.691 0.354 -1%

CLICK HERE for Complete Table with all bullets on Berger Website

G7 Form Factor Addition
Berger also added the G7 form factor to the Ballistics Quick Reference Sheet. The analysis of form factors can be very useful when considering a bullet’s long range performance potential. Going by BC alone can be deceptive since BC includes the weight and caliber of the bullet. Form factor indicates how much drag the bullet has, which is a very important consideration for all bullets of all calibers.

NEW Dual Twist-Rate Recommendations
Recommended twist rates for bullets are commonly listed as a single value, such as 1:12” (one rotation in 12″ of barrel travel). This may be overly simplistic. There is a big gray area of marginal stability in which bullets can fly with good accuracy, but with a reduced (i.e. sub-optimal) Ballistic Coefficient. Recognizing this reality, Berger is now listing two twist rates for each bullet it makes. The first is the minimum twist needed for good accuracy, which Berger has always recommended. The second is the new optimal twist rate, which is the twist that will stabilize the bullet to a level which achieves its full performance (BC) potential. CLICK HERE For more information.

Berger BC Ballistics Coefficient Barrel Twist Rate  Updates

Permalink Bullets, Brass, Ammo, Tech Tip 6 Comments »
September 12th, 2015

Coefficient Conundrum: G1 vs. G7, Which BC Should You Use

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 to that 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 preferrable 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.]

Permalink Bullets, Brass, Ammo 3 Comments »
July 16th, 2015

Barnes Calculates Ballistics Using Doppler Radar Speed Data

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedom

How do you build better (more precise) ammo drop tables? With radar, that’s how. Barnes Bullets is using Doppler Radar to develop the drop tables for its new Precision Match line of factory ammunition. The Doppler radar allows Barnes to determine actual velocities at hundreds of points along a bullet’s flight path. This provides a more complete view of the ballistics “behavior” of the bullet, particularly at long range. Using Doppler radar, Barnes has learned that neither the G1 nor G7 BC models are perfect. Barnes essentially builds a custom drag curve for each bullet using Doppler radar findings.

Use of Doppler Radar to Generate Trajectory Solutions

by Barnes Bullets, LLC
Typical trajectory tables are generated by measuring only two values: muzzle velocity, and either time-of-flight to a downrange target, or a second downrange velocity. Depending on the test facility where this data is gathered, that downrange target or chronograph may only be 100 to 300 yards from the muzzle. These values are used to calculate the Ballistic Coefficient (BC value) of the bullet, and the BC value is then referenced to a standardized drag curve such as G1 or G7 to generate the trajectory table.

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedomThis approach works reasonably well for the distances encountered in most hunting and target shooting conditions, but breaks down rapidly for long range work. It’s really an archaic approach based on artillery firings conducted in the late 1800s and computational techniques developed before the advent of modern computers.

There is a better approach which has been utilized by modern militaries around the world for many years to generate very precise firing solutions. Due to the sizeable investment required, it has been slow to make its way into the commercial market. This modern approach is to use a Doppler radar system to gather thousands of data points as a bullet flies downrange. This radar data is used to generate a bullet specific drag curve, and then fed into a modern 6 Degree of Freedom (DOF) [ballistics software program] to generate precise firing solutions and greatly increase first-round hit probability. (The 6 DOF software accounts for x, y, and z position along with the bullet’s pitch, yaw, and roll rates.)

Barnes has invested heavily in this modern approach. Our Doppler radar system can track bullets out to 1500 meters, recording the velocity and time of flight of that bullet every few feet along the flight path. Consider the graph below showing a bullet specific drag curve referenced to the more common G1 and G7 curves:

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedom

Neither of the standard curves is a particularly good match to our test bullet. In the legacy approach to generating a downrange trajectory table, the BC value is in effect a multiplier or a fudge factor that’s used to shift the drag curve of the test bullet to try and approximate one of the standard curves. This leads to heated arguments as to which of the standardized drag curves is a better fit, or if multiple BC values should be used to better approximate the standard curve (e.g., use one BC value when the velocity is between Mach 1 and Mach 2, and a different BC value when the velocity is between Mach 2 and Mach 3.) Barnes’ approach to creating trajectory tables is to generate bullet-specific drag curves, and use that data directly in a modern, state-of-the-art, 6 DOF ballistics program called Prodas to generate the firing solution.

Story tip from EdLongrange. We welcome reader submissions.
Permalink Bullets, Brass, Ammo, Tech Tip 7 Comments »
May 9th, 2015

Litz Field-Tests BCs of Sierra Tipped MatchKings

Following Sierra’s introduction of Tipped MatchKing (TMK) bullets, Bryan Litz of Applied Ballistics LLC has received many requests to determine the Ballistic Coefficient (BC) of these bullets through testing. Below are Litz’s findings for four out of the six bullets he has able to acquire and test so far.

Sierra Tipped MatchKing TMK Bullets Applied Ballistics G1 and G7 BC Coefficient

As you can see from the above table, when Sierra’s G1 BC is averaged for all speed ranges (which is representative of long range shooting) the results closely match the Applied Ballistics’ measurements of the same bullets, averaged from 3000 to 1500 FPS. The G7 BC doesn’t suffer nearly the velocity sensitivity as G1 and should be used for modern long range bullets when possible. Bryan tells us: “When I get the .22 caliber 77gr, and the .308 caliber 168gr tested, I’ll update the table.”

How do these Tipped MatchKings compare to standard MatchKings? According to Bryan’s measurements, here are some comparisons:

  • The 69gr TMK BC is +8% compared to the 69gr SMK
  • The 125gr TMK BC is -5% compared to the 125gr SMK (Litz believes this SMK was ‘pointed’)
  • The 155gr TMK BC is identical to that of the 155gr SMK (#2156, which is also pointed)
  • The 175gr TMK BC is +10% compared to the 175gr SMK

Bryan provided this additional advice for users of Ballistics programs: “Sierra’s stated BCs are measured by live fire, and are typically pretty accurate if the velocity bands are properly observed (7mm being the exception). A common error is to look at the BC that Sierra gives for your MV and just use that. Doing so overestimates the performance of the bullets over long range, and will cause you to hit low compared to your trajectory predictions.”

Permalink Bullets, Brass, Ammo 7 Comments »
January 6th, 2014

New Applied Ballistics Site Has Ballistics Calculator and More…

Applied Ballistics LLC has launched a completely updated website with many new features including an archive of FREE articles plus a full-featured online ballistics calculator. If you are interested in precision shooting, you should visit the “new and improved” Applied Ballistics website. Browse through the new content and try out the advanced Ballistics Calculator.

bullet data files

NEW Online Ballistics Calculator
There are many free online ballistics calculators, but the new Applied Ballistics web utility goes far beyond other web-based options. Bryan Litz states: “No ballistic solution can be more accurate than its inputs”. Accordingly, Applied Ballistics offers the most reliable BC data available — a built-in library of measured G1 and G7 BCs for over 200 bullets. The Online Ballistics Calculator also allows you to “offload” your results for use in the field in two ways. First, you can save a file for transfer to an Applied Ballistics Kestrel. (This process is supported with a ‘save profile’ option from the output page.) Alternatively, you can send the ballistics profile to Accuracy First DG to have a whiz wheel created.

bullet data files

The Online Ballistics Calculator has many “advanced” features. For example, you can enter sight scale factors to account for scopes which don’t track perfectly true, and also zero offsets which allows you to compensate for imperfect zeros. In addition, this is the first online ballistics program to provide dynamic WEZ (Weapon Employment Zone) analysis. This WEZ feature gives users the ability to calculate hit percentage on targets at a variety of ranges (and in various environments).

Bullet Data Files
The new website provides a number of detailed bullet data files. These data files include geometric dimensions, drag/BC data at multiple velocities, and detailed stability maps. The information is based on direct measurements and live fire testing conducted by Applied Ballistics.

bullet data files

Digital Media
The new Applied Ballistics website features a “digital library” of authoritative articles in PDF and eReader (Kindle, Nook) formats. You can download these FREE articles by clicking on the “Recreational” and “Professional” tabs at the top of Applied Ballistics Home Page, and then selecting “Recreational Articles” or “Professional Articles” from the pull-down menus.

Sample Ballistics Article
Gyroscopic (Spin) Drift and Coriolis Effect
Most long range shooters are aware of the effects of gravity, air resistance (drag), and wind vectors on their bullets’ trajectory. Gravity, drag, and wind are the major forces acting on a bullet in flight, but they’re not the only forces. In this article, Bryan Litz explains some of the more subtle forces that influence a bullet’s flight.

Sample Professional Article
300 Winchester Magnum vs. 338 Lapua Magnum WEZ Analysis
The specific intent of this Weapon Employment Zone (WEZ) report is to compare the ballistic performance of the 300 Winchester Magnum to the 338 Lapua Magnum with several available ammunition types. Understanding how these weapons compare in terms of hit percentage is important in the context of modern military applications.

Special Projects
Applied Ballistics is involved in some advanced, special projects. The new website showcases some of these high end ballistics solutions. Bryan Litz notes: “We have an active ballistics laboratory, highly capable contractors and industry partners who all contribute to provide practical and accurate solutions for a range of recreational and professional applications.”

Permalink Bullets, Brass, Ammo, New Product 3 Comments »
January 7th, 2013

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

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 to that 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 preferrable 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.]

Permalink Bullets, Brass, Ammo, Reloading 20 Comments »
January 2nd, 2013

Berger Hybrid Bullets — What You Need to Know

2013 SHOT Show Las VegasSHOT Show 2013 kicks off in two weeks in Las Vegas. One of our top priorities is to talk with the bullet makers from Berger, Hornady, Lapua, and Nosler.

At SHOT Show 2012 we chatted with Berger Ballistician Bryan Litz about Berger’s popular line of Hybrid bullets. Berger now offers a wide range of Hybrids in multiple calibers and weights. In fact, for .30-Caliber shooters, Berger now offers six different Hybrid match bullets, with weights from 155 grains up to 230 grains. New .338 Cal Tactical Hybrids were released in 2012 and big .375 Cal, and .408 Cal Hybrids are in the works (read more below).

Bryan tells us: “The hybrid design is Berger’s solution to the age old problem of precision vs. ease of use. This design is making life easier for handloaders as well as providing opportunities for commercial ammo loaders who need to offer a high performance round that also shoots precisely in many rifles with various chamber/throat configurations.”

For those not familiar with Hybrid bullets, the Hybrid design blends two common bullet nose shapes on the front section of the bullet (from the tip to the start of the bearing surface). Most of the curved section of the bullet has a Secant (VLD-style) ogive for low drag. This then blends in a Tangent-style ogive curve further back, where the bullet first contacts the rifling. The Tangent section makes seating depth less critical to accuracy, so the Hybrid bullet can shoot well through a range of seating depths, even though it has a very high Ballistic Coefficient (BC).

In the video we asked Bryan for recommended seating depths for 7mm and .30-Caliber Hybrid bullets. Bryan advises that, as a starting point, Hybrid bullets be seated .015″ (fifteen thousandths) off the lands in most barrels. Watch the video for more tips how to optimize your loads with Hybrid bullets.

Berger Hybrid Bullet

Berger is Developing New Large-Caliber and Hunting Hybrids
In related news, Berger announced that it will be offering a series of .338-caliber Hybrids. First Berger is reintroducing the Gen 1 .338 Cal, 300gr Hybrid bullet in Berger’s Hunting line. Berger will also be making a 250gr Hybrid Hunting bullet using the same type of jacket as the original Gen 1 300gr Hybrid bullet. In addition, Berger has released a .338 Cal 250gr Match Hybrid OTM Tactical bullet, along with a 300gr Match Hybrid OTM Tactical projectile.

More big bullets are on the drawing board. Our source says “.375 Caliber and then .408 Caliber are the next new calibers to be made at Berger”. These are in the design phase, and Berger needs to build a new machine, so the .375s and .408s will not be available until 2013 at the earliest.

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December 7th, 2012

Berger Bullets Rolls Out Redesigned and Enhanced Website

Report by Jeff Williams, AccurateShooter Correspondent
If you’ve visited BergerBullets.com lately, you’ve noticed that Berger Bullets has completely over-hauled and updated its website. The new website has a very handsome, clean layout. It is also faster to load and much easier to navigate. We give Berger an “A” grade for the new website.

Berger bullets

Berger bulletsOn Berger’s home page you’ll find product descriptions, easy-to-use (smart-phone friendly) product buttons, pull-down menus for all four Berger bullet line-ups, recent news items, plus videos. Click “Links” to access a comprehensive list of reloading resources with a directory of shooting association websites. Click the Berger Bulletin tab to read current product status reports, technical articles, and shooting tips.

Redesigned Bullet Info Tables
The bullet product info pages are much easier to read now. Simple tables display all the bullets of a particular type (hunting, target, varmint, and tactical), organized by caliber and weight within calibers. You’ll find BOTH G1 model and G7 model Ballistics coefficients (BCs) for all the bullets in the tables, and recommended twist rates are listed.

Berger bullets

Berger Twist-Rate Stability Calculator
The new Berger website also offers a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This very cool tool tells you if your chosen bullet will really stabilize in your barrel. LIVE DEMO BELOW — Just enter values in the data boxes and click “Calculate SG”.

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February 20th, 2011

FREE Ballistics Program from Berger Bullets

Berger Ballistics ProgramThere’s a lot of buzz about ballistics programs for smartphones. Those are handy, to be sure, but most people still need a solid, full-featured program to run on their home computers. Berger Bullets offers a sophisticated ballistics programs for MS Windows computers that works really well, and lets you print out results. Up-to-Date G7 BCs for Berger projectiles are built-in to the program, and the price is right — FREE.

CLICK HERE to Download Berger Ballistics Program

The program is basic enough to be easy to use, but flexible enough to allow you to calculate custom ballistics for your rifle and load. The program accounts for all the basic external ballistic parameters including bullet BC and muzzle velocity, atmospherics, uphill/downhill shooting, etc. The output tabulates velocity, energy and time of flight as a function of range. Bullet path and wind deflection are displayed in your choice of inches, centimeters, MOA or MILS.

Instructions for Program
On the Berger Bullets Blog (1/26/2010), You’ll find a description of program features and a complete set of instructions. Here are instructions for the bullet variables: “The bullet inputs are straightforward. The BC can be entered in reference to either the G1 or G7 standard. You can find the G1 or G7 BC for your bullet either printed on the bullet box label, or on our products page. For accurate results, you should measure the muzzle velocity with a good chronograph. If you don’t have access to a chronograph, you can estimate the muzzle velocity based on your load data.”

Tips for Best Results
Bryan Litz includes tips on getting the most from the Berger Ballistics program. Some of Bryan’s suggestions will also help you when working with other ballistics software:

G1 vs. G7 BC: The accuracy of the ballistic solution is only as accurate as the inputs you give it. The advertised BCs for Berger bullets are established by actual field firing tests over long range and are very accurate. Using the properly referenced BC (G7 vs. G1) for the bullet you’re modeling is important. For any bullet with a boat tail, we recommend using the G7 BC.

Muzzle Velocity: Knowing your true muzzle velocity is important when calculating external ballistics. It’s best to measure your muzzle velocity directly with a chronograph.

Altitude and Atmosphere: If you want a truly accurate long-range trajectory prediction, you can’t ignore atmospheric effects. This is especially true the farther you get from standard conditions (sea level altitude, 59 degrees Fahrenheit, 0% humidity).

Scope Verification: It’s important to verify the most important link between the calculated ballistics and your point of impact: your scope. If the ballistics program calculates 30.0 MOA of drop for a particular shot, and you dial your scope to 30.0 MOA, are you sure it’s giving you exactly 30.0 MOA? In reality, many scopes have enough error in them to cause misses at long range. It’s important to verify the value of your scope clicks by firing groups at short range.

If you have further questions not answered on Berger’s Blog Page, email Bryan.Litz [at] bergerbullets.com. NOTE: If your computer won’t run the program, please download and install this Java update: http://www.java.com/en/download/index.jsp. This is a Windows PC program. You may have problems trying to run it on a MAC in emulation.

Story sourced by Edlongrange.
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August 30th, 2008

Bryan Litz — Marksman, Rocket Scientist, Ballistics Guru

One of the great things about our Shooters’ Forum is that many uniquely talented shooters share their knowledge and test findings. One of those experts is “bsl135″ aka Bryan Litz. Bryan is no ordinary “weekend warrior”. He graduated from Penn State with a degree in Aerospace Engineering. He then began a career as a missile design engineer at Wright-Patterson Air Force Base. He has written many ballistics programs and technical papers dealing with long-range flight dynamics of projectiles. Bryan is also a superb long-range shooter, holding an NRA High Master Classification. At this year’s NRA National Championships at Camp Perry, Bryan beat 258 other competitors to win the Palma Individual Trophy Match. Bryan shot a remarkable 450/26x, not dropping a single point.

Breaking News: Just today, Bryan won the Ohio State Midrange Championship, an iron sights event with 15 shots each at 300, 500, and 600 yards. Bryan shot a spectacular 450/39X. Again, Bryan didn’t drop a point and his X-count would make this a new National Record, pending certification. Congrats Bryan!

Bryan also has his own website with a number of authoritative articles. Topics include: Bullet Design, Meplat Trimming, Gyroscopic and Coreolis Drift, Palma Bullet Analysis, How Ballistics Programs Work, and Ballistic Coefficient Testing. CLICK HERE to visit BRYAN LITZ Website.

7mm Bullet BC Testing — Evaluating the Numbers
Bryan does a lot of testing for bullet-makers, evaluating the performance of various bullet types. One thing he has observed is that manufacturers’ published BCs may vary considerably even for two bullet designs that appear to be nearly identical. In our Forum, Bryan offered this interesting analysis of the 7mm Berger 180gr VLD and the similar 7mm JLK 180gr VLD:

“I’ve developed a repeatable procedure for test firing bullets to determine ballistic coefficient. If you get Precision Shooting Magazine, the March issue has one of my articles about test firing the Berger .30 cal 155gr VLD. Long story short, my test procedure uses acoustic sensors in 200-yard increments to measure time of flight out to 600 or 1000 yards. My BC measurements are repeatable to within +/- 2%, usually within +/- 1%.

I have tested several 7mm bullets. Of particular interest are the Berger 180gr and JLK 180gr bullets. If you look at these bullets side by side, it’s hard to tell a difference between them. I believe the JLK bullet dies were made from the same set of prints as the Berger VLD (Design by Bill Davis of Tioga Engineering). So … why would these bullets have different [published] BCs? They’re the same weight and the same basic shape [with very minor differences in OAL and bearing surface length]. This is just the kind of smoke and mirrors that makes shooters think there is something mysterious about BCs and exterior ballistics that’s beyond the realm of human understanding. I was pleased with the results of my testing of these two bullets: the BC is virtually the same, as expected. All is right with the world.”

Drag Models — G7 is better than G1 for long-range Bullets
Most ballistics programs use the default G1 drag model. Bryan 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 are the results of my testing for these two bullets:

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.”

[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.]

Effect of Bullet Pointing
Bryan has also tested the effect of pointing bullets. He’s determined that this does have a positive (if small) effect on ballistics. Bryan writes: “I have measured the Berger 180 VLD in both nominal and pointed meplat configurations. Pointing the meplat from 0.059″ to 0.039″ increases the G7 BC from 0.337 lb/in² to 0.344 lb/in². This results in less than 2″ difference in 1000-yard wind drift (10 mph 90°). The improvement is small, perhaps negligible for standard decimal prone targets with large scoring rings. The improvement is more significant for F-Class targets with smaller scoring rings. That being said, I do point my own Berger 180 VLDs that I shoot in prone competition. It’s fast, easy, doesn’t hurt anything, and every little bit helps.”

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