Here’s a great tip from Forum member Greg C. (aka “Rem40X”). Greg has created a trajectory table with windage and elevation data for various distances and wind speeds. Greg prints out a compact version of his drop chart to place on his rifle. While many shooters tape a ‘come-up’ table on their buttstock, Greg has a better solution. He tapes the trajectory table to the outside of his front flip-up scope cover. This way, when he flips up the cover, his data is displayed for easy viewing right in front.
With your ‘come-up’ table on the flip-up cover you can check your windage and elevation easily without having to move up off the rifle and roll the gun over to look at the side of the stock. Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit. And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”
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Warner Tool Company (WTC) has introduced a new series of “Flat Line” ultra-high-BC bullets. These sleek, lathe-turned solids are some of the most perfectly-streamlined projectiles ever sold. The Ballistic Coefficients (BCs) of Flat Line projectiles are as much as 20% higher than other match bullets of similar caliber and weight. For example, the .30-caliber 200gr Flat Line bullet has a claimed G1 BC of 0.780. Compare that to 0.555 for the Sierra 200gr MatchKing and 0.622 for the Berger 200gr Hybrid.
The new Flat Line bullets all show extremely high Ballistic Coefficients for their weights:
Caliber
Description
Twist Rate
3000-1500 fps
3500-1500 fps
G1 BC
G7 BC
G1 BC
G7 BC
30
155.5gr Palma
10
0.553
0.285
0.576
0.290
30
175gr FTR
10
0.678
0.340
0.694
0.348
30
200gr
9
0.780
0.391
0.796
0.399
33
255.5gr LRBT
10
0.814
0.400
0.834
0.411
WTC also claims that Flat Line bullets can be launched at faster velocities than other bullets of similar caliber and weight. In its marketing materials, WTC says that Flat Line bullets deliver “Higher velocities when compared with projectiles in its weight class [and] much higher velocity when compared with projectiles of similar BC.” For example, WTC claims that “the 155.5gr .30-caliber bullet has the velocity of a 125-135gr bullet [with] the BC of a 185-200gr bullet.” It will be interesting to see if these claims can be verified in field tests.
Here are comparative G1 BCs for a variety of large .30-caliber bullets:
Cal Zant of the Precision Rifle Blog has obtained some early-production Flat Line bullets from their designer, Josh Kunz. Zant has written a lengthy article explaining the design and features of the new Flat Line bullets. If you are considering ordering some of these new lathe-turned solids, you should definitely read Zant’s report.
These bullets were designed by Aerospace engineer Josh Kunz using advanced computational fluid dynamics (CFD) to simulate supersonic air flow around the bullets. Through the use of advanced modeling and precision CNC machining, Kunz has developed extremely uniform, ballistically “slippery” bullets that fly faster and flatter than other projectiles of similar weight/caliber.
Premium Pricing: Flat Line Bullets Cost $125 to $165 per Hundred
These new Flat Line solid bullets are pricey. The 155s cost $1.25 per bullet and the price goes up from there. If you need large quantities of projectiles for a week-long match, the cost can be daunting. One hundred fifty of the 200-grainers will set you back $435.00! Here is a price list for the new Flat Line bullets. All quantities are in boxes of 50. Pricing is introductory and subject to change.
.30 Cal 155 grain
$62.50 per 50-ct box ($1.25 per bullet)
.30 Cal 180 grain
$67.50 per 50-ct box ($1.35 per bullet)
.30 Cal 200 grain
$72.50 per 50-ct box ($1.45 per bullet)
.338 Cal 255 grain
$82.50 per 50-ct box ($1.65 per bullet)
Is the cost worth it? When you look at the overall expense of attending a major match, and the fact that the top places in big matches are sometimes are decided by a single point (or X-Count), some competitors will spend the extra money for these ultra-high BC solids.
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.
This 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:
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.
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We know our readers are curious about the new Tipped MatchKings (TMKs) introduced by Sierra Bullets this year. Our friend Bill at Rifleshooter.com got hold of some of the .30-Cal 175-grain TMKs and tested them in his .308 Win rifle. He found the bullets were very consistent in weight. As for bearing surface, the SD was fairly low (.002″), but measurements varied from 0.400″ to 0.407″. Seven-thousandths extreme spread is more than we like to see, as it may affect accuracy. Therefore we recommend you sort by bearing surface length before loading these in match rounds.
Photo shows Bryan Litz (on right) and tester Mitchell Fitzpatrick. Bryan said: “Only 2,445 rounds to go! We’re testing over 50 ammo types in five different twist barrels… science can be exhausting!”
Do you know the actual BC (Ballistic Coefficient) of your rimfire ammunition? Well Applied Ballisitics will soon have answers for you. Bryan Litz and his team of testers have been working on a Herculean project. They’ve been testing over fifty types of .22 LR ammo, using five different twist-rate barrels.
Applied Ballistics has just released a fully upgraded version of its popular Tactical App for Android devices. Bryan Litz tells us: “AB Tactical has received a major overhaul (including a new Bullet Library with over 420 options). The upgrade will require that you uninstall the previous version that you have of the application and then install this new version. This is due to the complete re-write of the internal database handling.” NOTE: You need to record your gun-specific data before you install the new version. Details of the updated AB Tactical App are featured in the new 19-page USER Manual.
NOTE: This upgrade is for the Applied Ballistics Tactical Version only. There is no iPhone version of this App, and this is not the standard app that can be purchased from Google Play, or iTunes.
The new version of AB Tactical has a host of important enhancements:
Our friend Darrell Buell has a new Beast — a monster 64-inch-long .375 CheyTac that weighs more than 70 pounds! Designed for ultra-long-range shooting (two miles and beyond), this beast represents the state-of-the-art in extreme long-range rifles.
Darrell reports: “This rifle is pretty much purpose-built to shoot 2+ miles extremely accurately. It is a .375 CheyTac (lengthened) built on a BAT 2.5″ action. The custom 35″, 1:10″-twist Brux barrel is a fat, 2″-diameter ‘straight taper’ with fluting. A custom 5″-long muzzle brake is fitted at the end. All barreled action work was done by R.W. Snyder Custom Rifles. The stock was created to fit the build by PDC Custom, and the massive muzzle brake as well.” The “bridge” at the end may look like a barrel block, but it’s not — the barrel completely free-floats. (The Picatinny rail on top of the bridge allows use of an overhanging bipod as an alternative to the JoyPod).
Darrell has lots of elevation on tap: “With 150 MOA in the Ivey rings, another 20 MOA in the scope rail, 55 MOA in the Nightforce Competition scope, and 10 MOA in the FCR-1 reticle, there’s an impressive +235 MOA available.”
“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag….
Ruprecht Nennstiel, a forensic ballistics expert from Wiesbaden, Germany, has authored a great resource about bullet behavior in flight. Nennstiel’s comprehensive article, How Do Bullets Fly, explains all the forces which affect bullet flight including gravity, wind, gyroscopic effects, aerodynamic drag, and lift. Nennstiel even explains the rather arcane Magnus Force and Coriolis Effect which come into play at long ranges. Nennstiel’s remarkable resource contains many useful illustrations plus new experimental observations of bullets fired from small arms, both at short and at long ranges.
Shadowgraph of .308 Winchester Bullet
A convenient index is provided so you can study each particular force in sequence. Writing with clear, precise prose, Nennstiel explains each key factor that affects external ballistics. For starters, we all know that bullets spin when launched from a rifled barrel. But Nennstiel explains in greater detail how this spinning creates gyroscopic stability:
Here’s a report posted by long-range shooter Grizzman on the LiveLeak video hosting site. Grizzman engaged an 18″x24″ steel target at the distance of 2530 yards — 1.43 miles. Grizzman produced a great video that really gives you a sense of the distance (see the zoom footage at the 0:30 time mark). At this distance, the ballistics are remarkable. Grizzman’s .338-cal, 300gr Berger Hybrid bullets went transonic at 2400 yards and dropped 228 feet (69.5 meters) over their 2530-yard trajectory.
WATCH Video — Second camera at target records bullet impacts (see and hear the hits):
You’ve probably heard the term “Terminal Ballistics”. But do you really know what this refers to? Fundamentally, “Terminal Ballistics” describes the behavior of a projectile as it strikes, enters, and penetrates a target. Terminal Ballistics, then, can be said to describe projectile behavior in a target including the transfer of kinetic energy. Contrast this with “External Ballistics” which, generally speaking, describes and predicts how projectiles travel in flight. One way to look at this is that External Ballistics covers bullet behavior before impact, while terminal ballistics covers bullet behavior after impact.
The study of Terminal Ballistics is important for hunters, because it can predict how pellets, bullets, and slugs can perform on game. This NRA Firearm Science video illustrates Terminal Ballistics basics, defining key terms such as Impact Crater, Temporary Cavity, and Primary Cavity.
External Ballistics, also called “exterior ballistics”, is the part of ballistics that deals with the behavior of a non-powered projectile in flight.
Terminal Ballistics, a sub-field of ballistics, is the study of the behavior and effects of a projectile when it hits its target.
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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.
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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.
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Here’s a great tip from Forum member Greg C. (aka “Rem40X”). Greg has created a trajectory table with windage and elevation data for various distances and wind speeds. Greg prints out a compact version of his drop chart to place on his rifle. While many shooters tape a ‘come-up’ table on their buttstock, Greg has a better solution. He tapes the trajectory table to the outside of his front flip-up scope cover. This way, when he flips up the cover, his data is displayed for easy viewing right in front.
This 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.
