One obvious difference between G1 BCs and G7 BCs is that the numeric value of the G7 BC is lower than the numeric value of the G1 BC. For example, if a bullet has a G1 BC of .550, the G7 BC will be close to .282 (same bullet). Even though the G7 BC of .282 is a much more accurate representation of the bullet at all speeds, the numeric value of the G7 BC is lower. If you know anything about marketing, then it’s obvious why we’ve been stuck with G1 BCs for so long.
Since the G1 standard projectile is the highest drag standard, BCs referenced to that standard will be higher than BCs referenced to any other standard.
As we know, when it comes to marketing, the facts and quality of information is often compromised in order to present a more favorable advertisement. For many years, bullet makers have known¹ that the G1 standard is a poor standard for long range bullets but continue to use it. Why? One reason is because it’s believed that the first company to advertise G7 BCs will ‘confuse’ people, and the lower numeric value of the G7 BC will push people away from their product.
It’s easy to understand the fear of being the first to do something new. It will take time to explain and it may hurt sales at first. That’s OK. At Berger Bullets we are committed to the success of shooters. Mostly that means making the best bullets possible. That commitment also includes providing shooters with the most suitable and accurate information so they can use those bullets most effectively.
Berger’s commitment to the shooter is why we are making the leap to G7 referenced BCs. The change will take time to get used to, but in the end, shooters will be empowered to make better informed decisions about their equipment. In the end, shooters will be able to calculate more accurate trajectories. In the end, the other bullet companies will follow and provide G7 BCs for their long range bullets because it’s the right thing to do. In the end, this change will mean greater success for shooters.
Using the G7 BC: Calculating Trajectories
Most modern ballistics programs are being created with the ability to use BCs that are referenced to different standards (G1, G5, G7, etc). Calculating a trajectory with a G7 BC is as simple as selecting “G7 BC” in the program, and giving the program a G7 BC instead of a G1 BC. All the other inputs are handled the same.
There are many free ballistics programs that can calculate trajectories using G7 BCs including the well known free online calculator from JBM (http://www.eskimo.com/~jbm/cgi-bin/jbmtraj-5.0.cgi). The JBM program is extremely accurate when given accurate inputs. JBM’s page also has links to free ballistics programs that can be downloaded and run on your computer when not connected to the internet. One program that’s free for download and has the ability to use G7 BCs is AlBal (http://www.eskimo.com/~jbm/software/software.html).
Using the G7 BC: Comparing Bullets
One way that BC is used by shooters is to compare the relative performance of bullets. Comparing bullets by BC is only possible if the BCs are referenced to the same standard. For example, if you know the G1 BC of one bullet is .500, and the G7 BC for another bullet is .230, it’s impossible to tell which is better just from the BCs.
Since other bullet companies don’t yet advertise G7 BCs for their bullets, how is it possible to compare other brands' bullets to Berger’s G7 BC? Ideally, one tester would test the bullets from all the companies using the same method, and report the G7 BCs.
I have recently completed such a study and the test results including G7 BCs for over 175 bullets of all major brands are published in one book. The book is called: Applied Ballistics for Long Range Shooting and is available from Applied Ballistics, LLC (www.appliedballisticsllc.com/index_files/Book.htm). I began the testing and writing of this book several years before I became the Chief Ballistician for Berger Bullets. I used the same test procedure (repeatable within +/- 1%) to measure the G1 and G7 BCs for all brands of bullets so meaningful comparisons can be made between brands.
Science has a good track record as a method for reaching accurate conclusions. Ballistics is the science of shooting, and the use of the G1 standard has been a glaring error in the way that we shooters apply our science. For too long now, the unfortunate influences of marketing and advertising have kept us from being able to use our science to its fullest potential.
As part of our commitment to the success of shooters, Berger Bullets is bringing the application of small arms ballistics out of the marketing hype and G1 dark ages and offering accurate and properly referenced G7 BCs for our long range bullets.
All of the pieces are now in place for shooters to take full advantage of this more accurate kind of BC. Berger now provides G7 BCs for our bullets. The book: Applied Ballistics for Long Range Shooting provides G7 BCs for all other brands of bullets. Ballistics programs are available that can calculate trajectories using the G7 BCs. In conclusion; everything is now available for shooters to take immediate advantage of this new type of BC and do everything that was possible with the old G1 BCs, only better.
¹Sierra Bullets wrote an article: http://www.exteriorballistics.com/ebexplained/articles/the_ballistic_coefficient.pdf which acknowledges that G7 referenced BCs are more appropriate for modern long range bullets.
Bryan Litz majored in Aerospace Engineering at Penn State University and worked on air-to-air missile design for 6 years in the US Air Force before taking a job as Berger Bullets Chief Ballistician in November 2008. Bryan is now 29 years old, and has been an avid long range shooter since the age of 15. In particular, Bryan enjoys NRA Long Range Prone Fullbore/Palma competition and is the current National Palma Champion. Bryan is also a husband and proud father of 3.
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