ABM Ammo, a division of Berger Bullets, has introduced new, high performance .308 Winchester factory ammunition, loaded with the high-BC, 185gr Berger Juggernauts. The long-loaded “Match Ready” version of this ammo is designed for Palma (Full-bore) and F-TR shooters. A “Mission Ready” version, loaded shorter to mag length, is designed for tactical and military applications. These two new offerings should “raise the bar” for long-range performance with factory .308 Win ammo.
Offering a high Ballistic Coefficient (0.560 G1, 0.283 G7), the 185-grain .308-caliber Juggernaut bullet is designed to remain stable even in the transonic zone. This way it offers good performance at extended distances, contributing to higher hit percentages at longer ranges.
Berger Twist-Rate Stability Calculator
On the updated Berger Bullets website you’ll find 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”.
Berger Bullets has just announced a new 6.5 mm (.264 caliber) 130gr Hybrid projectile. Optimized for magazine-length seating (and AR10-friendly), the new 130gr bullets should be ideal for tactical comps and the PRS series. We expect this new bullet to work great when loaded in modern mid-size cartridges such as the 6.5×47 Lapua and 6.5 Creedmoor. Berger’s new 6.5mm 130gr Match AR Hybrid OTM Tactical bullet (could Berger come up with a longer name?) will soon be released to the public. Berger says this new 130-grainer is the first of many new bullet designs to be introduced in the next few years. Here is a run-down on the new bullet from its designer, Bryan Litz of Applied Ballistics.
NEW 130gr Hybrid — Behind the Design
by Bryan Litz, Berger Chief Ballistician
Intelligent bullet design and selection begins with an understanding of application constraints. For bullets that will be used in unlimited rifles, there are few constraints and performance can truly be maximized. However, many shooting applications have realistic constraints such as magazine feeding of loaded rounds. In constrained applications, you need to ask the question: “What’s the best bullet that will work within the constraints of my shooting application?”
The new Berger 6.5mm 130 grain AR Hybrid OTM Tactical bullet is specifically optimized for maximum performance in magazine-length ammo.
6.5mm cartridges are the second most common cartridges used by top shooters in many of the Precision Rifle Series (PRS) matches, with 6mm being the most common. These kinds of tactical matches all have stages that require repeating rifles — either AR-10 platforms or bolt guns — so magazine feeding is a must. Recognizing that Berger did not have an option that was truly optimized for this particular application, we went to work and the latest 6.5mm Hybrid is the result.
SUMMARY
The new Berger 6.5mm 130 grain AR Hybrid OTM Tactical bullet is specifically optimized for use in loaded ammo with COAL constraints for magazine feeding. This bullet maximizes overall performance through BC as well as achievable muzzle velocity in mid-capacity 6.5mm cartridges fed from AR-length magazines.
What makes this bullet optimal for magazine length ammo? To start with, the nose of the bullet is constrained in length so that when it’s loaded to mag length in 6.5mm cartridges such as the 6.5mm Creedmoor, 260 Remington and 6.5×47 Lapua, the nose of the bullet won’t be pushed below the case mouth. This can be an issue with some of the heavier 6.5mm bullets like the 140s. Furthermore, the hybrid ogive design is not sensitive to jump distance like some other designs such as the VLD.
Another consideration of length-constrained ammo is how much of the bullet is pushed down into the case. The inside of the case is for powder, and the more space you take up with bullet, the less powder you can fit in. Less powder means less total energy available, and muzzle velocity is depressed. A bullet weight of 130 grains is an optimal balance between external ballistic performance (BC) and internal case capacity considerations which translate into muzzle velocity. Further to this objective, the AR Hybrid has a minimal air gap in the front of the nose, which allows the bullet to have an even shorter OAL. When dealing with length-constrained designs, you need to pack as much bullet into as little length as possible< to optimize overall performance. Another advantage of making the bullet shorter is that stability, including transonic stability, is improved.
Although this design is length-constrained, the combination of a hybrid ogive and 7 degree Boat Tail produce a very respectable G7 form factor of 0.920 which is within 1% of the popular 6mm 105 grain Hybrid. See below for full live fire ballistic performance data.
The 6.5mm 130 grain AR Hybrid will be barely stable from a 1:9″ twist, and reaches full stability from a 1:8″ twist which is common for many 6.5mm rifles. Visit the Berger Bullets twist rate calculator to get more detailed stability information on your specific barrel twist, muzzle velocity and environment.
Cartridge Selection for Magazine Length Constraint — Advanced Analysis
The trend to smaller calibers in magazine-fed rifles is happening for a very good reason. For a .308 Winchester round, you only have 2.37 calibers of nose length available for the bullet to protrude from the case. Such a short nose will have relatively high drag for the caliber. By contrast, smaller calibers such as 6.5mm and 6mm have proportionally more length available for the nose to protrude from the case and still fit in the same COAL constraint. Proportionally longer noses mean lower drag. Proportionally longer bullets mean higher sectional density. Combine an elevated sectional density with lower drag, and you get higher BC bullets. For example, consider a 175 grain .30 caliber bullet commonly used in .308 Winchester M118LR-type ammo. These 175 grain bullets have G7 BCs in the neighborhood of .243 to .260. Neck the .308 down to 6.5mm (260 Remington) or 6mm (.243 Winchester) and now look at the BCs of the bullets available in these calibers which work within the same magazine length constraint. The 6.5mm 130 grain AR Hybrid has a G7 BC of 0.290, and the 6mm 105 grain Hybrid has a G7 BC of 0.278 — both of which are higher than the .30 cal 175 grain bullet BC. Furthermore, you get hundreds of feet per second more velocity with the necked-down cartridges as well.
All of the above translates into higher hit percentage. See the caliber comparison chart below* which is an excerpt taken from the book: Modern Advancements in Long Range Shooting which addresses this and many other topics in even more detail.
*The Weapon Employment Zone (WEZ) analysis shown above is for a 1000-yard shot on a standard IPSC silhouette in an uncertain environment having: +/- 2 mph wind, +/- 1 yard range, Muzzle Velocity SD of 10 fps, and a rifle shooting 1 MOA groups.
Ever wondered how a modern, jacketed bullet is made? Thanks to Berger Bullets, here’s a short video clip that shows how bullets are crafted. In this short sequence filmed at Berger’s factory, you can see machinery that forms the jacket, inserts the core, and then forms the final shape.
Walt Berger, a living legend in the benchrest world, was honored this past weekend at the Ben Avery Range outside Phoenix, AZ. At the start of the 2015 Cactus Classic Benchrest match, a “surprise” ceremony was held. Berger President Eric Stecker announced to the crowd that the 100/200-yard benchrest facility was being dedicated to Walt Berger, founder of Berger Bullets. Walt was genuinely surprised and moved by the special ceremony, which featured a color guard, and a fly-over. In the photo above, Walt is flanked by his grandson David Hamilton (left) and Eric Stecker (right).
As part of the range dedication ceremony, four vintage, WWII-era Warbirds flew over the range in diamond formation, streaming red, white, and blue smoke.
Shortly after the ceremony, the competitors got down to business…
More Spin, Less Drag
In this article, we look at how twist rate and stability affect the Ballistic Coefficient (BC) of a bullet. Again, this topic is covered in detail in the Modern Advancements book. Through our testing, we’ve learned that adequate spin-stabilization is important to achieving the best BC (and lowest drag). In other words, if you don’t spin your bullets fast enough (with sufficient twist rate), the BC of your bullets may be less than optimal. That means, in practical terms, that your bullets drop more quickly and deflect more in the wind (other factors being equal). Spin your bullets faster, and you can optimize your BC for best performance.
Any test that’s designed to study BC effects has to be carefully controlled in the sense that the variables are isolated. To this end, barrels were ordered from a single barrel smith, chambered and headspaced to the same rifle, with the only difference being the twist rate of the barrels. In this test, 3 pairs of barrels were used. In .224 caliber, 1:9” and 1:7” twist. In .243 caliber it was 1:10” and 1:8”, and in .30 caliber it was 1:12” and 1:10”. Other than the twist rates, each pair of barrels was identical in length, contour, and had similar round counts. Here is a barrel rack at the Applied Ballistics Lab:
Applied Ballistics used multiple barrels to study how twist rate affects BC.
“The Modern Advancements series is basically a journal of the ongoing R&D efforts of the Applied Ballistics Laboratory. The goal of the series is to share what we’re learning about ballistics so others can benefit.” –Bryan Litz
Barrel twist rate along with velocity, atmospherics, and bullet design all combine to result in a Gyroscopic Stability Factor (SG). It’s the SG that actually correlates to BC. The testing revealed that if you get SG above 1.5, the BC may improve slightly with faster twist (higher SG), but it’s very difficult to see. However, BC drops off very quickly for SGs below 1.5. This can be seen in the figure below from Modern Advancements in Long Range Shooting.
The chart shows that when the Gyroscopic Stability Factor (SG) is above 1.5, BC is mostly constant. But if SG falls below 1.5, BC drops off dramatically.
Note that the BC drops by about 3% for every 0.1 that SG falls below 1.5. The data supports a correlation coefficient of 0.87 for this relationship. That means the 3% per 0.1 unit of SG is an accurate trend, but isn’t necessarily exact for every scenario.
It’s a common assumption that if a shooter is seeing great groups and round holes, that he’s seeing the full potential BC of the bullets. These tests did not support that assumption. It’s quite common to shoot very tight groups and have round bullet holes while your BC is compromised by as much as 10% or more. This is probably the most practical and important take-away from this test.
To calculate the SG of your bullets in your rifle, visit the Berger Bullets online stability calculator. This FREE calculator will show you the SG of your bullets, as well as indicate if your BC will be compromised (and by how much) if the SG is below 1.5. With the stated twist rate of your barrel, if your selected bullet shows an SG of 1.5 (or less), the calculator will suggest alternate bullets that will fully stabilize in your rifle. This valuable online resource is based directly on live fire testing. You can use the SG Calculator for free on the web — you don’t need to download software.
Learn More About SG and BC This article is just a brief overview of the interrelated subjects of twist rate, Gyroscopic Stability, and BC. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests.
Other chapters in the book’s twist rate section include: · Stability and Drag – Supersonic
· Stability and Drag – Transonic
· Spin Rate Decay
· Effect of Twist rate on Precision
Other sections of the book include: Modern Rifles, Scopes, and Bullets as well as Advancements in Predictive Modeling. This book is sold through the Applied Ballistics online store. Modern Advancements in Long Range Shooting is also available in eBook format in the Amazon Kindle store.
At the 2015 Berger Southwest Nationals, Forum member Erik Cortina cornered Bryan Litz of Applied Ballistics. Erik, the F-Open winner in the 600-yard Mid-Range match, was curious about bullet sorting. Knowing that bullets can be sorted by many different criteria (e.g. weight, overall length, base to ogive length, actual bearing surface length etc.) Erik asked Bryan to specify the most important dimension to consider when sorting. Bryan recommended sorting by “Base to Ogive”. Litz noted that: “Sorting by overall length can be misleading because of the nature of the open-tip match bullet. You might get a bullet that measures longer because it has a jagged [tip], but that bullet might not fly any different. But measuring base to ogive might indicate that the bullet is formed differently — basically it’s a higher resolution measurement….”
Ballistics Q & A in Shooter’s Forum
Got more questions about bullets? Our Shooters’ Forum has a special area for Bullets & Ballistics topics. There you can get your own questions about bullets and ballistics answered by Bryan Litz and other experts from Applied Ballistics.
Competitors at the 2015 Berger Southwest Nationals were treated to something special on Saturday morning. After a short address by Eric Stecker, fireworks boomed from downrange and a flight of three warbirds streamed overhead, trailing smoke. Watch these dramatic moments in the video below.
This ceremony marked the dedication of Ben Avery’s 1000-yard range as the Middleton Tompkins Range. With his family by his side, Mid was recognized for his achievements in the shooting sports and his decades of service. This was a heart-warming event honoring Mid, a six-time National High Power Rifle Champion, and the leading member of America’s first family of shooting. Wife Nancy Tompkins and step-daughters Sherri Jo Gallagher and Michelle Gallagher have all been National rifle champions (High Power and/or Long-Range). This was an emotional day for Mid — he revealed to us that this was certainly one of the greatest highlights of his life.
Berger President Eric Stecker speaks at range dedication ceremony. Mid Tompkins stands with his family members Sherri Jo Gallagher (to Mid’s left), wife Nancy Tompkins, and Michelle Gallagher.
Along with the dedication of the 1000-yard range, a ribbon-cutting ceremony was held for the new multi-purpose facility at Ben Avery. Situated at the 1000-yard range, this facility was constructed with $420,000 in funding from Berger Bullets and Nightforce Optics. Mid Tompkins cut the red ribbon on the facility’s front doors, officially opening the multi-purpose center for public use.
Mid jokes with the crowd, showing his quick-witted sense of humor.
Panorama of Middleton Tompkins 1000-Yard Range at Ben Avery (CLICK to ZOOM)
Interview with Past NRA President John Sigler at Ben Avery
In the video below, we interview past NRA President John Sigler. An avid long-range shooter himself, John is the current chairman of the NRA High Power Committee. John was at Ben Avery this week competing in the F-Open Division. John says that the emergence of the F-Class discipline has extended his competitive shooting career. He had high praise for the Ben Avery Range and the new multi-purpose building dedicated on February 14th.
Guest Article By Michelle Gallagher, Berger Bullets
Let’s face it. In the world of firearms, there is something for everyone. Do you like to compete? Are you a hunter? Are you more of a shotgun shooter or rifle shooter? Do you enjoy running around between stages of a timed course, or does the thought of shooting one-hole groups appeal to you more? Even though many of us shoot several different firearms and disciplines, chances are very good that we all have a favorite. Are we spreading ourselves too thin by shooting different disciplines, or is it actually beneficial? I have found that participating in multiple disciplines can actually improve your performance. Every style of shooting is different; therefore, they each develop different skills that benefit each other.
How can cross-training in other disciplines help you? For example, I am most familiar with long-range prone shooting, so let’s start there. To be a successful long-range shooter, you must have a stable position, accurate ammunition, and good wind-reading skills. You can improve all of these areas through time and effort, but there are other ways to improve more efficiently. Spend some time practicing smallbore. Smallbore rifles and targets are much less forgiving when it comes to position and shot execution. Long-range targets are very large, so you can get away with accepting less than perfect shots. Shooting smallbore will make you focus more on shooting perfectly center shots every time. Another way to do this with your High Power rifle is to shoot on reduced targets at long ranges. This will also force you to accept nothing less than perfect. Shoot at an F-Class target with your iron sights. At 1000 yards, the X-Ring on a long range target is 10 inches; it is 5 inches on an F-Class target. Because of this, you will have to focus harder on sight alignment to hit a center shot. When you go back to the conventional target, you will be amazed at how large the ten ring looks.
Also, most prone rifles can be fitted with a bipod. Put a bipod and scope on your rifle, and shoot F-TR. Shooting with a scope and bipod eliminates position and eyesight factors, and will allow you to concentrate on learning how to more accurately read the wind. The smaller target will force you to be more aggressive on your wind calls. It will also help encourage you to use better loading techniques. Nothing is more frustrating than making a correct wind call on that tiny target, only to lose the point out the top or bottom due to inferior ammunition. If you put in the effort to shoot good scores on the F-Class target, you will be amazed how much easier the long-range target looks when you return to your sling and iron sights. By the same token, F-Class shooters sometimes prefer to shoot fast and chase the spotter. Shooting prone can help teach patience in choosing a wind condition to shoot in, and waiting for that condition to return if it changes.
Benchrest shooters are arguably among the most knowledgeable about reloading. If you want to learn better techniques about loading ammunition, you might want to spend some time at benchrest matches. You might not be in contention to win, but you will certainly learn a lot about reloading and gun handling. Shooting F-Open can also teach you these skills, as it is closely related to benchrest. Benchrest shooters may learn new wind-reading techniques by shooting mid- or long-range F-Class matches.
Position shooters can also improve their skills by shooting different disciplines. High Power Across-the-Course shooters benefit from shooting smallbore and air rifle. Again, these targets are very small, which will encourage competitors to be more critical of their shot placement. Hunters may benefit from shooting silhouette matches, which will give them practice when shooting standing with a scoped rifle. Tactical matches may also be good, as tactical matches involve improvising shots from various positions and distances. [Editor: Many tactical matches also involve hiking or moving from position to position — this can motivate a shooter to maintain a good level of general fitness.]
These are just a few ways that you can benefit from branching out into other shooting disciplines. Talk to the other shooters. There is a wealth of knowledge in every discipline, and the other shooters will be more than happy to share what they have learned. Try something new. You may be surprised what you get out of it. You will certainly learn new skills and improve the ones you already have. You might develop a deeper appreciation for the discipline you started off with, or you may just discover a new passion.
This article originally appeared in the Berger Bulletin. The Berger Bulletin blog contains the latest info on Berger products, along with informative articles on target shooting and hunting.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2 by Bryan Litz forBerger Bullets. Part One of this series focused on the importance of COAL in terms of SAAMI standards, magazine lengths, seating depths, and pressure levels. Another measure of length for loaded ammunition is highly important to precision, namely Cartridge Base to Bullet Ogive Length (CBTO).
Figure 2. Chamber throat geometry showing the bullet jump to the rifling or lands.
Look at Figure 2. Suppose the bullet was seated out of the case to the point where the base of the bullet’s nose (ogive) just contacted the beginning of the riflings (the lands) when the bolt was closed. This bullet seating configuration is referred to as touching the lands, or touching the riflings and is a very important measurement to understand for precision hand-loading. Due to the complex dynamics of internal ballistics which happen in the blink of an eye, the distance a bullet moves out of the case before it engages the riflings is highly critical to precision potential. Therefore, in order to systematically optimize the precision of his handloads, it’s critically important that the precision hand-loader understands how to alter bullet seating depth in relation to the barrel rifling. Part of the required knowledge is understanding how to accurately and repeatably measure the Cartridge Base To Ogive (CBTO) dimension. This is explained in the FULL ARTICLE.
Bryan Litz offers an extended discussion on how to measure CBTO using different tools and methods, including the Hornady OAL gauge. You can read this discussion in the full article found on the Berger Bullets website. CLICK HERE to Read Full Article.
Why Not Use CBTO as a SAAMI Standard?
If CBTO is so important to rifle accuracy, you might ask, “Why is it not listed as the SAAMI spec standard in addition to COAL?” There is one primary reason why it is not listed in the standard. This is the lack of uniformity in bullet nose shapes and measuring devices used to determine CBTO.
Figure 4. Two different bullet shapes, seated to the same CBTO length, but different COAL. Note the shiny scratches on the bullets made by the comparator tool which indicates a point on the bullet ogive near where the ogive will engage the riflings.
Benefits of Having a Uniform CBTO
There is another aspect to knowing your CBTO when checking your COAL as it pertains to performance. With good bullets, tooling, and carefully-prepared cases you can easily achieve a CBTO that varies less than +/- .001″ but your COAL can vary as much as .025″ extreme spread (or more with other brands). This is not necessarily bad and it is much better than the other way around. If you have a CBTO dimension that varies but your COAL dimension is tight (within +/- .002″) then it is most likely that your bullet is bottoming out inside the seater cone on the bullet tip. This is very bad and is to be avoided. It is normal for bullets to have precisely the same nose shape and it is also normal for these same bullets to have nose lengths that can vary as much as .025″.
Summary of Cartridge Base To Ogive (CBTO) Discussion
Here are four important considerations regarding bullet seating depth as it relates to CBTO:
1. CBTO is a critical measurement to understand for handloaders because it’s directly related to precision potential, and you control it by simply setting bullet seating depth.
2. Tools and methods for measuring CBTO vary. Most of the measurement techniques have pitfalls (which may give rise to inconsistent results) that you should understand before starting out.
3. A CBTO that produces the best precision in your rifle may not produce the best precision in someone else’s rifle. Even if you have the same rifle, same bullets, same model of comparator gauges, etc. It’s possible that the gauges are not actually the same, and measurements from one don’t translate to the same dimension for another.
4. Once you find the CBTO that produces the best precision in your rifle, it’s important to allow minimal variation in that dimension when producing quality handloads. This is achieved by using quality bullets, tooling, and properly preparing case mouths and necks for consistent seating.
Proportionally longer noses mean lower drag. Proportionally longer bullets mean higher sectional density. Combine an elevated sectional density with lower drag, and you get higher BC bullets. For example, consider a 175 grain .30 caliber bullet commonly used in .308 Winchester M118LR-type ammo. These 175 grain bullets have G7 BCs in the neighborhood of .243 to .260. Neck the .308 down to 6.5mm (260 Remington) or 6mm (.243 Winchester) and now look at the BCs of the bullets available in these calibers which work within the same magazine length constraint. The 6.5mm 130 grain AR Hybrid has a G7 BC of 0.290, and the 6mm 105 grain Hybrid has a G7 BC of 0.278 — both of which are higher than the .30 cal 175 grain bullet BC. Furthermore, you get hundreds of feet per second more velocity with the necked-down cartridges as well.
Position shooters can also improve their skills by shooting different disciplines. High Power Across-the-Course shooters benefit from shooting smallbore and air rifle. Again, these targets are very small, which will encourage competitors to be more critical of their shot placement. Hunters may benefit from shooting silhouette matches, which will give them practice when shooting standing with a scoped rifle. Tactical matches may also be good, as tactical matches involve improvising shots from various positions and distances. [Editor: Many tactical matches also involve hiking or moving from position to position — this can motivate a shooter to maintain a good level of general fitness.]
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2
