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October 26th, 2014
 Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2
by Bryan Litz for Berger 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″.
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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.
CLICK HERE to Read Full Article with More Info |
Article sourced by EdLongrange. We welcome tips from readers.
October 12th, 2014
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
by Bryan Litz for Berger Bullets.
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. Cartridge Overall Length (COAL) is also a variable that can be used to fine-tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a magazine. In this article, we’ll explore the various effects of COAL, and what choices a shooter can make to maximize the effectiveness of their hand loads.
Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI)
Most loading manuals (including the Berger Manual), present loading data according to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) standards. SAAMI provides max pressure, COAL and many other specifications for commercial cartridges so that rifle makers, ammo makers, and hand loaders can standardize their products so they all work together. As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.
Bullet seating depth is an important variable in the accuracy equation. In many cases, the SAAMI specified COAL is shorter than what a hand loader wants to load their rounds to for accuracy purposes. In the case where a hand loader seats the bullets longer than SAAMI specified COAL, there are some internal ballistic effects that take place which are important to understand.
Effects of Seating Depth / COAL on Pressure and Velocity
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long. In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short.
Figure 1. When the bullet is seated farther out of the case, there is more volume available for powder. This enables the cartridge to generate higher muzzle velocity with the same pressure.
When you think about it, it makes good sense. After all, when you seat the bullet out longer and leave more internal case volume for powder, you’re effectively making the cartridge into a bigger cartridge by increasing the size of the combustion chamber. Figure 1 illustrates the extra volume that’s available for powder when the bullet is seated out long.
Before concluding that it’s a good idea to start seating your bullets longer than SAAMI spec length, there are a few things to consider.
Geometry of a Chamber Throat
The chamber in a rifle will have a certain throat length which will dictate how long a bullet can be loaded. The throat is the forward portion of the chamber that has no rifling. The portion of the bullet’s bearing surface that projects out of the case occupies the throat (see Figure 2).
The length of the throat determines how much of the bullet can stick out of the case. When a cartridge is chambered and the bullet encounters the beginning of the rifling, known as the lands, it’s met with hard resistance. This COAL marks the maximum length that a bullet can be seated. When a bullet is seated out to contact the lands, its initial forward motion during ignition is immediately resisted by an engraving force.
Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.
A very common practice in precision reloading is to establish the COAL for a bullet that’s seated to touch the lands. This is a reference length that the hand loader works from when searching for the optimal seating depth for precision. Many times, the best seating depth is with the bullet touching or very near the lands. However, in some rifles, the best seating depth might be 0.100″ or more off the lands. This is simply a variable the hand loader uses to tune the precision of a rifle.
CLICK HERE to Read Full Article with More Info
Article sourced by EdLongrange. We welcome tips from readers.
October 1st, 2014
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 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.
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°.”
September 12th, 2014
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It’s been seven years since L.P. Brezny wrote the original Gun Digest Book of Long-Range Shooting. Much has changed in the long-distance shooting game in that time. Brezny addresses those developments in this completely updated Second Edition, set to be released September 25, 2014.
Highlights of Book of Long-Range Shooting (2nd Edition)
– Best new factory rifles for long-range shooting
– New calibers and loadings
– The best big bore, heavy bullet choices for 1,000 yards and beyond
– Recommended optics, accessories, chronographs, and techniques
– Popular new shooting sports: 3-Gun Competition and “Rifle Golf” |
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Experienced firearms writer L.P. Brezny has completely updated his popular, original book on long-range rifles and shooting techniques. Readers will find up-to-date information on recent advances in long-range rifles and cartridge choices. The updated Second Edition offers hundreds of new photos and much new information on guns, optics, and ammunition.
Brezny also offers instructional “how-to” content for shooters looking to develop their technique. He draws from first-hand experience, as well as interviews with snipers and long-range competitors. Brezny discusses current military applied combat theory — new methods that help snipers achieve hits at ultra-long range. Last but not least, Brezny explores today’s popular competitive shooting events, including 3-gun competition and long distance “rifle golf.”
NOTE: This book has a lot of useful information, but it is written more for the tactical crowd than for long-range benchrest or F-Class shooters. This book is a good starting point if you want to get started in the long-range game. However, you’ll probably find more serious information about advanced reloading right here in the AccurateShooter.com archives. If you want to understand the fine points of long-range ballistics, then get Bryan Litz’s Applied Ballisitics for Long-Range Shooting (2d. Ed), now available in eBook as well as hard-cover format.
August 20th, 2014
The Canadian National Fullbore Rifle Championships (CFRC) are underway this week at the Connaught Range near Ottawa, Ontario. Following on the Canadian F-Class Championships held last week, this event is for “Target Rifles”, shot with slings. So far, a British Lady, Jane Messer, is leading the pack, but two Americans, Kent Reeve and Bryan Litz, are close behind.
Bryan Litz provides this report from Canada: “Had a great time shooting today! I won the Letson sub-Aggregate and moved up to Third Place in the overall. We (Team USA Hardin) also tied for winning the coaches two-man team match with USA Praslick at 900 meters. Here’s how the leader board stacks up: Jane Messer from the UK is still leading at 1 down, Kent Reeve moved into second at 2 down, and I’m in third with 3 down. There will be two more days of individual matches and then a lot of team matches leading up to the America Match on Sunday.”
Team USA Hardin: John Whidden (L), Coach Steve Hardin, and Bryan Litz (R).
August 8th, 2014
Berger Bullets is now in the ammo business, offering high-quality, loaded ammunition for competition, hunting, and tactical applications. Berger will sell ammo through its new company, Applied Ballistics Munitions (aka “ABM” or “ABM Ammo”). See ABM’s ammunition offerings at www.abmammo.com.
 ABM Ammo will offer precision rifle ammunition for three popular cartridge types: .308 Winchester, .300 Winchester Magnum, and .338 Lapua Magnum. There are three product lines. The “Mission Ready” line is designed for military and tactical use. In addition, ABM will offer “Hunt Ready” ammo for precision hunters and “Match Ready” ammunition for target shooters.
Each product line is loaded with the Berger bullet that best fits a given application. Each of the bullets used have been proven performers among the hand loading community for years and in some cases, decades. The chart below shows the current bullet selections for each of the three product lines:
ABM Ammo Components are Tested Lot by Lot
ABM uses high quality components and tooling to produce the most consistent ammunition possible. In a process developed by ballistics expert Bryan Litz, ABM ammo has been engineered and tested in the Applied Ballistics laboratory. ABM actually tests each individual lot of components used in the loaded cartridges to ensure quality and consistency.
Eric Stecker, President of Applied Ballistics Munitions relays, “Launching an ammunition company in today’s firearm market environment has been a challenging experience. The product will speak for itself among the shooters as to why it is so important that we pursue this effort.” To learn more about Applied Ballistics Munitions, visit www.abmammo.com.
August 6th, 2014
Berger Bullets has improved its online stability calculator. Tests have shown that bullets can suffer from reduced BC if the bullet rpm (spin rate) is less than optimal, even if barrel twist rate is otherwise fast enough to stabilize bullets in flight. Now, the improved, free Stability Calculator can determine if you need a faster-twist barrel to enjoy the best BC from your bullets.
CLICK HERE for FREE Berger Twist Rate Stability Calculator
By Bryan Litz, Chief Ballistician for Berger Bullets
We’re happy to announce a major upgrade to our Twist Rate Stability Calculator which is free to use on the Berger Bullets webpage. The old stability calculator was pretty basic, and would simply return a gyroscopic stability number based on your bullet, twist rate, and atmospheric conditions. This was used to determine if your barrels twist rate was fast enough to stabilize a particular bullet or not, based on the Gyroscopic Stability Factor (SG) being greater than 1.4.
Stability and BC — How Bullet RPM Affects Ballistic Coefficients
The new calculator still calculates SG, but also goes much further. In addition to calculating stability, the upgraded calculator can also tell you if your stability level is harming the effective BC of your bullets or not. Extensive testing has proven that bullets fired with stability levels between 1.2 and 1.5 can fly with excellent precision (good groups), but suffer from a depressed BC, sometimes as much as 10%. Shooting the bullets from faster twist rate barrels allows for the bullets to fly better and realize their full BC potential.
July 14th, 2014
 iPhone and iPad users rejoice. The Apple iOS version of the Applied Ballistics Mobile App is now available. It has all the features of the much-loved Applied Ballistics Android App with full Apple functionality. This mobile App will run on iPhones, iPods, and iPads.
Price is $29.99. Click here to view details or order the App: Applied Ballistics iOS App.
CLICK HERE for Detailed Summary of App Features (Applied Ballistics Website)
The new iOS mobile App accounts for all major and minor trajectory variables that a shooter could encounter. Conveniently, the App displays single-shot solutions in HUD View or Reticle View.
Real-World Calibration — Shooters can enter their observed drops and the program will calibrate and “true” the predictions based on actual bullet impact. This is done by incorporating muzzle velocity and drop-scaling over various segments of the trajectory.
Sync to Web — A web-sync feature allows you to store your rifle and ammunition libraries online. And you can backup all the profiles online or restore them to a device.
Forum member Snuggie308, who acquired the new iOS App, gives it a thumbs up: “I bought it last night. It is a great tool. There’s a massive data base … built into it. You can’t find a better [mobile ballistics app] in my opinion.” Snuggie308 also reports that the new iOS is iPad friendly, and fills the iPad screen so it is easy to use all the features.
The Applied Ballistics iOS Mobile App runs the state-of-the-art Point Mass ballistic solver. This solver, along with the built-in library of ballistic coefficients, makes this the most accurate, precise, and complete mobile ballistics app available for iOS devices.
Ballistician (and former missile design engineer) Bryan Litz wrote this solver. The program integrates the equations of ballistic motion numerically, using a 4th-order Runge-Kutta method, the preferred method of solving dynamic equations for aircraft and missiles. The application also comes with G1 and G7 BCs for over 1,300 bullet types.
Bryan Litz tells us: “We have worked extensively on this product. With the success of the Android version of the application, released two years ago, the demand for the iOS version has been high. We are excited to now offer a full-featured iOS version that runs on iPhones, iPods, and iPads.”
Available now through iTunes, the Applied Ballistics Mobile App costs $29.99, and requires iOS 7.0 or later for proper functionality. Compatible with iPhone, iPad, and iPod touch devices, this App is optimized for the iPhone 5 series of smart phones.
June 26th, 2014
 Applied 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.
June 24th, 2014
Bryan Litz shot his first F-TR match recently, and he came up a winner — a big winner. Competing at the Midwest Palma event, Bryan topped the F-TR field, winning by 15 points. In fact Bryan ended up finishing within 10 points of F-Open winner Alex Lipworth. In the 20-shot, 1000-yard matches, Bryan averaged an impressive 195-7X, with a stunning 196-11X score in one match. (Consider that the 1000-yard X-Ring is just five inches in diameter!) Not bad for Bryan’s first attempt at the F-TR game.
We all know Bryan has serious long-range shooting skills. But he also had a secret weapon — a wickedly accurate, wood/carbon-stocked, low-profile F-TR rifle built by John Pierce. With this Pierce rifle, Bryan had to abandon the hard-holding style he uses in sling-shooting competition. Instead he adopted a “less is more”, almost-free-recoil method — and it worked. Is this the future of F-TR? Read on and learn what Bryan has to say about F-TR shooting, “belly benchrest” style.
Sling Shooter Tries F-TR
by Bryan Litz
I’ve been coaching the Michigan F-TR team for a while and finally decided to participate in the competition. F-TR is more rifle-centric than Palma, meaning the precision demands are greater due to the smaller scoring rings. After seeing Eric Stecker’s results with his Pierce rifle at the 2014 Berger Southwest Nationals, I asked my good friend and Michigan team-mate John Pierce to “build me one like Eric’s”. This is the same basic set up as John’s own F-TR rifle as well. It’s a Pierce F-TR action with a 30″ long, 1:9″ twist Bartlein Barrel chambered for the Berger 215gr Hybrids. The barreled action is bedded into a light-weight, BR-style stock built by Bob Scoville. A Phoenix bipod underneath and a Nightforce 15-55X Competition scope complete the package.
Click Image to Zoom
Loading the .308 Winchester with Berger 215gr Hybrids
I received the rifle just one week before the Midwest Palma match. During that week prior to the match, I put over 700 rounds on the rifle. I did some load development but was mostly learning to shoot a new rifle in a new discipline. I settled on 215gr Berger Hybrids seated 0.015″ off the riflings over a stout charge of Varget in Lapua Palma (small primer) brass with CCI BR4 primers. The only brass prep was mandreling the necks of the new brass for consistent neck tension. Bullets were slightly pointed, but nothing was segregated by weight, base-to-ogive, or anything. All the ammo I shot in Lodi was loaded in brand-new Lapua brass.
Check Out Bryan’s Set-up with the Rifle (Click Photo to Zoom)
Learning the F-TR Game — Adapting to a New Shooting Style
Coming over from sling shooting, I knew there would be unique challenges to F-TR which I wanted to learn prior to (not during) a major tournament. I learned a new shooting position which doesn’t involve drawing the right knee up. For F-TR I get more straight behind the gun rather than at an angle. I found that the rifle shoots best with very light cheek, shoulder and grip pressure, approaching free recoil. This is how Eric Stecker shot his similar rifle into second place in the SW Nationals. I learned the rifle’s sensitivity to different bipod and rear bag supports, and found the best buttplate position to allow the rifle to track and stay on target after recoil. This set-up shot best with a mostly free-recoil approach, that means “hovering” over the comb, rather than resting your head on the stock. This took some “getting used to” in terms of neck and back muscle tone. These are the kind of details I think it’s important to focus on when entering a new dicipline.
“I love the way this Pierce F-TR rifle flings brass, and wins tournaments. None of my sling guns ever had an ejector. With this rig, it’s become one of my favorite things to eject the brass and just let it fly!”
I think many shooters consider themselves ‘ready for a match’ the first time the rifle shows them a couple 1/3 or 1/4 MOA 5-shot groups from a bench at 100 yards. While making the rifle shoot precisely is certainly a prerequisite for successful match shooting, it’s certainly not the whole story. So as soon as I got the load and rifle shooting 1/2 MOA from the bench, I proceeded to shoot many 10- and 20-shot strings from the ground at 300 and 1000 yards. I shot more than 500 rounds this way, studying the rifles character, and learning to shoot it. It’s amazing how much the precision (grouping) is affected by subtle variables in the set-up, especially when shooting heavy bullets. I truly believe that many F-TR rifles are hindered in their precision potential by something in the way they are set up and shot.
Advice on Shooting the Heavy Bullets in a .308 Win
I believe F-TR set-ups are way more forgiving with light- to medium-weight bullets (155 to 185 grains). By this I mean that it’s easier to shoot good groups with a variety of bipods, rear bags, etc. But as you get into the 200 – 215 grain bullet weights, the precision of the rifle (i.e. group size) becomes very sensitive to set-up and shot execution. I was able to find a good set-up which let the rifle shoot very well on a variety of surfaces (hard gravel, soft grass, sand, etc.). In Lodi, the rifle shot well all week.
Having done so much preparation and training with the rifle the week prior to the match, I felt very prepared and confident. The results were actually better than expected. There were no problems at all with equipment, and I just shot the rifle the way it liked to be shot. In the end, I won the F-TR Division. I can say there were many shooters interested in the Pierce rifle!
Impressive Performance
Bryan observes that this rifle held 1/2 MOA of vertical at 1000 yards for 17 out of 20 shots. That’s impressive accuracy. Bryan was in first place each day of the match, including the 3×1000 on Friday where he averaged over 195-7X. Remarkably, Bryan finished just 10 points behind the F-Open winner, with the next closest F-TR competitor 15 points behind Bryan. In fact, with his .308 Win, Bryan out-scored 75% of the F-Open shooters. CLICK for match results.
Bryan gave credit to his smiths and his team-mates: “I’d like to thank John Pierce for building a great F-TR rifle and thank my dad, Bill Litz, for loading the best ammo on the planet. Finally, I’d like to thank the Michigan F-TR team for helping me learn how to shoot F-TR.”
Bryan writes: “Here I am with ‘The Man’, John Pierce, and the epic F-TR rifle he built for me. This thing shoots ‘No S***’ 1/2 MOA Vertical at 1000 yards.”
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