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March 16th, 2011
In discussions of ballistics, you’ll see references to “tangent” and “secant” bullet shapes. We know that, for many readers, these terms can be confusing. To add to the confusion, bullet makers don’t always identify their projectiles as secant or tangent designs. This article provides a basic explanation of tangent and secant designs, to help you understand the characteristics of both bullet shapes.
Tangent Ogive vs. Secant Ogive vs. Hybrid
Most match bullets produced today use a tangent ogive profile, but the modern VLD-style bullets employ a secant profile. To further complicate matters, the latest generation of “Hybrid” projectiles from Berger Bullets feature a blended secant + tangent profile to combine the best qualities of both nose shapes. The secant section provides reduced drag, while the tangent section makes the bullet easier to tune, i.e. less sensitive to seating depth position.
Berger Bullets ballistician Bryan Litz explains tangent and secant bullet ogive designs in a glossary section of his Applied Ballistics website, which we reprint below. Bryan then explains how tangent and secant profiles can be combined in a “hybrid” design.
How Bullet Ogive Curves are Defined
While the term “ogive” is often used to describe the particular point on the bullet where the curve reaches full bullet diameter, in fact the “ogive” properly refers to the entire curve of the bullet from the tip to the full-diameter straight section — the shank. Understanding then, that the ogive is a curve, how is that curve described?
LITZ: The ogive of a bullet is usually characterized by the length of its radius. This radius is often given in calibers instead of inches. For example, an 8 ogive 6mm bullet has an ogive that is a segment of a circular arc with a radius of 8*.243 = 1.952”. A .30-caliber bullet with an 8 ogive will be proportionally the same as the 8 ogive 6mm bullet, but the actual radius will be 2.464” for the .30 caliber bullet.
For a given nose length, if an ogive is perfectly tangent, it will have a very specific radius. Any radius longer than that will cause the ogive to be secant. Secant ogives can range from very mild (short radius) to very aggressive (long radius). The drag of a secant ogive is minimized when its radius is twice as long as a tangent ogive radius. In other words, if a tangent ogive has an 8 caliber radius, then the longest practical secant ogive radius is 16 calibers long for a given nose length.”
Secant Ogive vs. Tangent Ogive
 
Ogive metrics, and Rt/R
LITZ: There is a number that’s used to quantify how secant an ogive is. The metric is known as the Rt/R ratio and it’s the ratio of the tangent ogive radius to the actual ogive radius for a given bullet. In the above example, the 16 caliber ogive would have an Rt/R ratio of 0.5. The number 0.5 is therefore the lowest practical value for the Rt/R ratio, and represents the minimum drag ogive for a given length. An ogive that’s perfectly tangent will have an Rt/R ratio of 1.0. Most ogives are in between an Rt/R of 1.0 and 0.5. The dimensioned drawings at the end of my Applied Ballistics book provide the bullets ogive radius in calibers, as well as the Rt/R ratio. In short, the Rt/R ratio is simply a measure of how secant an ogive is. 1.0 is not secant at all, 0.5 is as secant as it gets.
Hybrid Bullet Design — Best of Both Worlds?
Bryan Litz has been developing a number of modern “Hybrid” design bullets for Berger. The objective of Bryan’s design work has been to achieve a very low drag design that is also “not finicky”. Normal (non-hybrid) secant designs, such as the Berger 105gr VLD, deliver very impressive BC values, but the bullets can be sensitive to seating depth. Montana’s Tom Mousel has set world records with the Berger 105gr VLD in his 6mm Dasher, but he tells us “seating depth is critical to the best accuracy”. Tom says a change of .005″ in seating depth “can cause the group size to increase substantially”. In an effort to produce more forgiving high-BC bullets, Bryan Litz has developed a hybrid tangent/secant bullet shape. This is explained in the illustration below.
Story sourced by Edlongrange.
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February 18th, 2011
 Lapua now offers a FREE ballistics program for modern smart phones that run Java Apps. (Unfortunately, that excludes Apple iPhones and Android OS phones, but Lapua says that the majority of smartphones run Java). The program calculates drift and drop, and it corrects for altitude, temp, air pressure, and shot angle. The Lapua Ballistics App also includes a database of Lapua bullet profiles with ultra-reliable radar-derived Ballistic Coefficients. Sound good? Now go get your smart phone. The program must be downloaded with a mobile phone. Open a web browser in your smart-phone and navigate to www.lapua.com/ballistics and choose the correct version for your phone.
Lapua’s exterior ballistic software for mobile phones is capable of predicting trajectories in real time with extreme accuracy. Using Lapua Ballistics, there is no need for checking tables and calculating cosines for inclination compensation (you still have to input the angle). The program also compensates for the effect of cartridge temperature on muzzle velocity and the effect of atmospheric conditions on the projectile’s trajectory.
Lapua Ballistics is based on precise Doppler Radar measurements of actual bullet drag — professional data available only for Lapua bullets. Lapua Ballistics can be installed on all smartphones supporting basic Java (Java MIDP 2.0). NOTE: Apple iPhone and Android platforms do not support Java ME.
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January 31st, 2011
Barnes Bullets is introducing a bunch of new bullets for 2011. Precision shooters will be interested in the new Match Burner line of bullets, as well as Barnes’ LRX series of long-range projectiles. For the large-caliber shooters, Barnes has also expanded its line of Banded Solids, in weights from 250 grains (.338 caliber) all the way up to 535 grains (.500 Jeffries).
The new Barnes Match Burner bullets are designed for competitive target shooting. The new Match Burners for 2011, listed below, are slated to ship to vendors in March.
| Caliber |
Weight |
Description |
| 223 Cal |
52-grain |
Flat Base Match |
| 223 Cal |
69-grain |
Boattail Match (1:10″ Twist or Faster) |
| 223 Cal |
85-grain |
Boattail Match (1:7″ Twist or Faster) |
| 6MM |
68-grain |
Flat Base Match |
| 6MM |
105-grain |
Boattail Match |
| 6.5MM |
140-grain |
Boattail Match |
| 30 Cal |
155-grain |
Boattail Palma |
| 30 Cal |
175-grain |
Boattail Match |
New Long-Range X Bullets Based on Tipped Triple-Shock Design
The all-new Long-Range X Bullet® (LRX) line includes four new bullets. Designed after the best-selling Tipped Triple-Shock™ X Bullet® (TTSX), the new LRX bullet design increases B.C. values by increasing ogive and boat tail lengths to improve the bullets’ long-range ballistic performance. LRX bullets are manufactured with the proven 100-percent copper, lead-free bodies. The bullet’s polymer tip initiates expansion, causing the nose cavity to open instantly on contact, doubling the bullet’s original diameter. Barnes claims the LRX bullets allow clean, quick kills even at extreme ranges.
| Caliber |
Weight |
Description |
| 7MM |
145-grain |
Boattail |
| 30 Cal |
175-grain |
Boattail (1:11″ Twist or Faster) |
| 30 Cal |
200-grain |
Boattail (1:10″ Twist or Faster) |
| 338 Lapua |
265-grain |
Boattail |
Solid Bullets with Drive Bands
Barnes Banded Solids are made from free-machining brass. A series of bands cut into the bullet’s shank moderate engraving pressure and help reduce barrel wear. Weight-matched with Triple-Shock X Bullets of the same caliber, Banded Solids can be interchanged with expanding TSX bullets without varying point of impact.
Precision machined from the same tough material, Banded Solid Spitzers deliver maximum concentricity, consistent density and match-grade accuracy. According to Barnes, the Banded Solid Spitzers, provide deep penetration without deformation. Barnes says these bullets can “Kill fur-bearing animals cleanly with minimal damage to valuable pelts”.
| Caliber |
Weight |
Description |
| .338 Cal |
250-grain |
Banded Solid Round Nose |
| 9.3MM |
250-grain |
Banded Solid Round Nose |
| 9.3MM |
286-grain |
Banded Solid Round Nose |
| .375 Cal |
270-grain |
Banded Solid Round Nose |
| .375 Cal |
300-grain |
Banded Solid Round Nose |
| .375 Cal |
350-grain |
Banded Solid Round Nose |
| .416 Cal |
350-grain |
Banded Solid Round Nose |
| .416 Cal |
400-grain |
Banded Solid Round Nose |
| .422″ (404 JEFF) |
400-grain |
Banded Solid Round Nose |
| .458 Cal |
450-grain |
Banded Solid Round Nose |
| .458 Cal |
500-grain |
Banded Solid Round Nose |
| .504″ (505 GIBBS) |
525-grain |
Banded Solid Round Nose |
| .510″ (500 JEFF) |
535-grain |
Banded Solid Round Nose |
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January 29th, 2011
 GS Custom Bullets has been producing high-quality hunting and target bullets in South Africa since 1993. GS Custom Bullets specializes in monometal solids. For hunters, the GS solids have proven extremely effective on game animals, including the biggest species on the African continent. The GS match bullets are CNC-machined to very exacting tolerances, offering superior concentricity and uniformity. The large match bullets feature drive bands for reduced engraving force, and an extremely slippery shape for exceptionally high ballistic coefficients. GS has made a special 1,100-grain 50-caliber projectile that has a calculated G1 BC of 1.85! This bullet, launched at 3400 fps, can stay supersonic out to 4,000 meters — that’s 2.49 miles!
Gerard Schultz, founder of GS Custom Bullets, holds a number of patents on his bullet designs. Currently GS Custom is selling to the American market through its South African website, GSCustom.co.ZA. However, this year GS Custom hopes to expand production to North America, starting a production facility in the USA. The North American effort will be lead by Gerard Schultz’s daughter, Gina, and her husband Anthony. They can be contacted through GSCustomUSA.com. We met with Gina and Anthony at SHOT Show in Las Vegas and learned more about these remarkable bullet designs. The video is worth watching. These are no ordinary bullets.
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October 6th, 2010
Hornady plans to release a brand new 285gr, .338-caliber match bullet within the next few weeks. This bullet, which boasts a mind-blowing 0.735 G1 BC, has already proven itself in competition. At the 2010 IBS 1000-yard Nationals in September, Scott Fletcher won the Heavy Gun (HG) group title shooting the new Hornady 285gr BTHPs. Scott’s 4-match, 10-shot per target group Aggregate was 9.148″. Scott was shooting a large wildcat, the .338 Sloan. That cartridge is nearly identical to the new .338 Norma Magnum*, which could be described as a “chopped” .338 Lapua Mag — shorter with less case capacity.
Weight is unlimited in the 1000-yard Heavy Gun class. Weight soaks up the recoil of big cartridges like the .338 Norma Magnum, making them manageable to shoot. The Big 30-Cals have long dominated this HG category, but some shooters like Fletcher are experimenting with some really big cartridge/bullet combinations, in pursuit of class-leading ballistics. We don’t know how fast Fletcher pushes his prototype Hornady 285s, but that 0.735 BC has to give the bullets awesome performance in the wind.
Artist’s concept — No photos of the new bullet are available.
New Manufacturing Process Produces Bullets with Near-Zero Run-out
According to Hornady’s Chief Ballistic Scientist Dave Emary, the new 285-grainer is a VLD-style, secant ogive projectile with a standard, drawn-copper jacket and lead core. This is a BTHP, NOT a plastic tip bullet like Hornady’s A-Max designs. Emary says, “This bullet was originally developed for the military. It has just about the lowest drag possible with conventional bullet construction and ogive design.” The .338-caliber 285gr bullet is the first of two new super-low drag bullets Hornady will be releasing before the end of the year.
The new 285gr bullets are built with a new manufacturing process that improves jacket concentricity to previously unattainable levels. Emary says: “Measured along the entire jacket, these bullets have extremely low eccentricity. We measured zero to a couple ten-thousandths total run-out along the whole jacket. As a result the bullet has show truly outstanding long-range performance, with sub-half-MOA accuracy at extreme ranges.” Hornady Project Engineer (and 1K shooter) Joe Thielen added: “These bullets are specifically designed and built for long-range use, and the jackets are the some of best I’ve ever seen.”
When will the new bullets be available? End of the year at the latest. Emary says the 285s should be available “before the end of November”. When we asked Hornady Marketing guru Steve Johnson, he said “Soon. They’ll be out soon.” When pressed as to “how soon”, Steve responded: “The release is imminent… imminent”.
*The .338 Norma Magnum was originally developed by the American sport shooter Jimmie Sloan as a long-range sport shooting wildcat cartridge. It was designed to shoot the .338-caliber, 300gr Sierra MatchKing projectile from actions/magazines too short for a .338 Lapua Magnum. Sloan licensed the design to the Norma group. Both the .338 Norma Mag and the larger .338 Lapua Mag are derived from the .416 Jeffreys, but the .338 Norma Mag fits in a shorter action.
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August 20th, 2010
Savage’s Fullbore (Palma) rifle team performed well in recent competitions. The four-man team (Darrell Buell of Damascus, OR, John Weil of Welches, OR, Monte Milanuk of Wenatchee WA, and Stan Pate of Milwaukie, OR) wrapped up the season with two internationally-sanctioned matches. The first was the Canadian International Fullbore Championships in Chilliwack, B.C. and and the second was the Pacific International Fullbore Championships held just outside of Portland, OR. At both matches, elite shooters from around the world competed at 800, 900 and 1,000 yards. The two matches combined constitute a “Super Aggregate”, or Continental Title.
Team members (L to R): John Weil, Darrell Buell, Monte Milanuk and Stan Pate. (File Photo 2009).
Team Savage loaded up on the hardware at both matches, winning multiple medals at the various distances. Savage’s four shooters captured the team gold at the Canadian match and Gold and Silver in the individual Super Aggregate.
At the Pacific Int’l match in Oregon, local knowledge helped Team Savage rack up the medals. This competition was held on Weil and Pate’s home range at the Douglass Ridge Rifle Club. With John Weil leading the way, Team Savage put on a clinic: Weil won all seven gold medals available, while teammate Pate won six silvers. Milanuk added three bronzes. Weil also shot an impressive 148-4X at 1000 yards. In the video below, Team Captain Stan Pate demonstrates the accuracy of the Savage Palma (Fullbore) rifle, nailing a steel target at 1169 yards.
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March 29th, 2010
The 2010 U.S. F-Class Nationals concluded yesterday. It was a big success, drawing nearly 120 individual competitors and 18 teams. Young Derek Rodgers (Sharpshooter Class, 1330-57X) from Albuquerque, New Mexico, is the new Open Class Champion, and Californian Lane Buxton (1302-42X) won the F-TR division using a .308 Win Palma Rifle with Sierra #2156 bullets. Forum member Ken Dickerman finished second in F-Open posting a 1325-57X. Past multi-time F-TR Champ Danny Biggs shot F-Open this year, finishing third with a 1324-67X. While we are still waiting to receive ALL the final official results, it appears Danny set the high X-count for the match, while shooting with a Sinclair bipod equipped with a vertical adjustment knob. (The Open-class guns work amazingly well off the wide-base bipods.) Charles Ballard, the reigning (back to back) F-Open champ, finished seventh in F-Open.
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New F-Open Champ Derek Rodgers was shooting a 300 WSM with 210-grain bullets. This heavy bullet/short magnum combo performed well in the windy afternoon conditions during Sunday’s afternoon matches. Most of the other top F-Open competitors were shooting a .284 Win or some other 7mm. Charles Ballard told us told us: “with so many guys shooting 7mms this year, the competition is tougher than ever. If I had a caliber advantage before… that’s gone. With the winds we had in the afternoons, I’m not surprised Derek Rogers did well with his 300 WSM and the heavy bullets. I want to congratulate Derek on his well-deserved win.”
The team event was hotly contested, with 18 teams on the line, most of which were in F-TR Class. In Open Class, the North American Shooters Team, coached by Bryan Litz won the Berger Trophy for the 600 + 1000-yard combined Aggregate, as well as the 1000-yard Team Match. The Sierra Spindle Shooters team took first place in the 600-yard Team Match. In F-TR Team shooting, Savage Shooters pulled off a clean sweep, winning the 600-yard match, the 1000-yard match, AND the Team Aggregate. Congrats to Savage Shooters!
NAS Team shooters (left to right): David Mann, Dean Morris, Bryan Litz (coach), Rick Jenson, Larry Tait.
F-Open Class Results
Winner: Derek Rodgers (Sharpshooter) – 1330-57X Nat’l Champion
Second: Ken Dickerman (High Master) – 1325-57X
Third: Danny Biggs – 1324-67X – High X Count?
Fourth: Jeff Cochran – 1324-28X
Fifth: Jeff Traylor – 1323-51X
High Woman: Brenda Hill – 1302-31X
High Senior: Larry Bartholome – 1321-51X
High Grand Senior: Danny Biggs – 1324-67X
F-TR Class Results
Winner: Lane Buxton – 1302-42X – National Champion
Second: Robert Lach – 1297-36X
Third: John Hayhurst – 1293-37X
Fourth: Jeffery Rorer – 1293-28X
High Senior: Robert Lach – 1297-36X
High Grand Senior: Peter Church – 1279-31X
Complete Results for Download
Check the attachments for all the scores. FCNAT2010OPEN.doc has all the F Open scores and FCNAT2010TR.doc has all the F-TR scores.
Download All F-Open Scores/Standings | Download All F-TR Scores/Standings
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July 16th, 2009
 Bryan Litz, chief Ballistician for Berger Bullets, has just released an impressive new, hard-cover treatise on external ballistics. While Bryan’s 536-page Applied Ballistics for Long-Range Shooting will surely take its place among the “classic” reference books on precision shooting, it does much more than explain theories of bullet flight. Using advanced equipment, Litz measured the actual drag of over 175 popular bullet types in the field. Armed with this new experimentally-derived data, shooters can now calculate their loads’ true trajectories with greater precision than ever before.
If you’re serious about long-range shooting, or just have an interest in bullet design and performance, you should buy this book. It is offered for $39.95 directly from Bryan’s website, AppliedBallisticsLLC.com.
In the video above, Litz explains some of the key features of his new book. (Watch the video — Bryan explains what you’ll get for your $39.95!) Don’t be fooled by Bryan’s youthful appearance. This guy is the Einstein of external ballistics. He holds a degree in Aerospace Engineering, and he was an honest-to-goodness rocket scientist who worked with the U.S. Air Force on air-to-air missile design for six years before joning Berger Bullets. What’s more, Bryan is an extremely talented long-range shooter. Bryan was the 2008 National Palma Champion, and he holds the all-time NRA mid-range iron-sight record (450-39X).
Even if you rely on a software program to calculate your come-ups, it is important to know how bullets are affected by wind and gravity, and how bullet ballistic coefficients are determined. If you’re looking to expand your knowledge of ballistics and the nuances of bullet design, you should find Bryan’s book informative and readable.
You don’t need an MIT degree to understand this book. It was Bryan’s goal to explain the important elements of exterior ballistics in a practical way that can be understood and applied by shooters. What you learn from Applied Ballistics for Long-Range Shooting can help you make better decisions about the bullet(s) and the caliber(s) you choose to shoot, and give you more confidence when taking those long shots in the field.
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May 31st, 2009
Hornady’s 75gr A-Max BTHP bullet is among the more popular bullets used by service rifle shooters. The plastic-tipped projectile also works well in 22-250s and 22 BRs with 1:8.5″ (or faster) barrels. The 75gr A-Max boasts an excellent 0.435 BC, which is higher than the claimed BCs for both the Sierra 77gr MatchKing (0.372 @ 3000+ fps) and the Sierra 80gr MatchKing (.420 @ 2200+ fps).
High-BC 22 Cal Moly A-Maxs for under $20/100
Because Service Rifle competitors must shoot long strings of fire without cleaning, many prefer to shoot moly-coated bullets. Varminters likewise appreciate the fact that coated bullets may extend cleaning intervals. PrecisionReloading.com currently has moly-coated 75gr A-Maxs on sale for just $19.65 per hundred. That’s a good deal for bullets that are more than capable of winning Service Rifle matches. Consider that Sierra 77gr MKs are selling elsewhere for $25-$28.00 per hundred. If you have a fast-twist .224 and you like Moly, you may want to snap up some A-Maxs at this discounted price.
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April 16th, 2009
The HuntingNut.com website offers Point Blank Ballistics and Reloading software free of charge. That’s right, the program is absolutely free, forever — not just for a trial period. We use Point Blank all the time, not just to calculate come-ups and windage for our rifles, but also to compare ballistics among various chamberings, or to compare different bullets. With Point Blank it is easy to just change your bullet BC value and instantly see the effect on windage and drop. Point Blank will even calculate muzzle energy and recoil force. Point Blank will also hold all your reloading info in a built-in database. You enter the caliber (chambering), bullet, powder, velocity, and other important variables. Then you can quickly access hundreds of different load combinations.
CLICK HERE TO download PointBlank Reloading & Ballistics Software v2.0 ZIP Archive.
(Note: this 1.13mb file is for Windows computers; you need WinZip or other program to unzip the file archive.)
You can even use Point Blank to plot your shots on a test target. This way you can easily compare the accuracy of different “recipes” during load development. You can record up to 10 shots per target.
Calculate Recoil, Muzzle Energy, Knock-Out Power
Point Blank has many other useful functions. Click on the “Misc Functions” tab, and you’ll find the program will calculate recoil and muzzle energy. If you clock bullet speed at both the muzzle and a 100-yard target, the program will also calculate actual bullet Balllistic Coefficient. For hunters, the program calculates Taylor Knock-Out values, and the program even provides handy English/Metric unit conversions.
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April 1st, 2009
At the U.S. Army’s Aberdeen Proving Ground, a team of ballistics technicians, supported by some of the U.S. Army’s top sniper instructors, has been quietly developing a radical new “dimpled” bullet. The exterior of the bullet resembles the dimpled surface of a golf ball. The function of the special dimpled skin is to reduce projectile drag, providing a flatter long-range trajectory, and greater retained energy at the target.
.338 Projectile with MIM Exo-Jacket
(3D-CAD Artist’s Rendering) |
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In their pursuit of a lower-drag bullet, the Army tried a variety of designs, including bullets with circumferential drive bands, dual-radius ogives, and rebated boat-tails. The dimpled “golf-ball” design was considered a “long shot” according to the design team, but it has performed beyond all expectations. The nominal drag coefficient (Cd) has improved by about +.040, while cartridge muzzle velocity has increased by nearly 80+ fps because the bullet’s dimpled skin reduces in-barrel friction. What’s more — the terminal performance of the dimpled bullet has been “spectacular”. The Aberdeen team set out to produce a slightly more slippery bullet for U.S. Army snipers. What they ended up with is a bullet with dramatically enhanced long-range ballistics and superior killing power on “soft targets”.
 Lt. Col. Ben Eldrick, Long-Range Projectile Project (LRPP) team leader, told AccurateShooter.com how the radical bullet was conceived: “During our initial design work, we wanted the benefits of a high-BC, pointed bullet, but in a design that could be mass-produced and could work as a tracer. We consulted some of the top civilian bullet experts, including ballistician Bryan Litz of Berger Bullets. Mr. Litz really got the ball rolling. He suggested that the ‘next big step’ in bullet design would involve the turbulent boundary layer over the body of the bullet. Litz told us that ‘pointing bullet tips will take you only so far… think about optimizing the airflow over the entire bullet’. That made a lot of sense to us. When you design a race car to be aerodynamic, you sculpt the whole body, not just the front bumper.”
Lt. Col. Eldrick continued: “It turns out Litz was right on the money. By employing a golf-ball type dimpled surface, we were able to optimize the turbulent boundary layer on the bullet body. This reduced the low-pressure wake zone behind the bullet significantly, resulting in reduced base drag. As a result the bullet experiences much less overall drag, effectively raising the BC.” The Army team had discovered that what works for golf balls also works for bullets.
 After testing a series of prototypes, the Aberdeen bullet design team settled on a copper-jacketed bullet with dimples about 0.5 mm in diameter. The first-generation bullets were formed in special binary impact swages that press-form the dimples after the bullets were pointed up in conventional dies. Future production bullets will be made with an advanced metal-injection-molding (MIM) process that forms the dimples directly into the surface of the bullets. Rather than simply wrap the core material (which is classified), the MIM is molecularly bonded to the core. The Aberdeen LRPP team calls this “Exo-Jacket” construction, as in “Exo-Skeleton”.
 Higher Velocities Achieved
There was a surprise benefit of the dimpled bullet design — higher muzzle velocities. Given the same powder charge, dimpled bullets exit the muzzle faster because they produce less in-barrel friction than do conventional bullets. This is because the recessed dimples effectively reduce the metal-on-metal bearing surface. Lt. Col. Eldrick revealed: “the added velocity was an unexpected bonus. With equal-pressure loads, dimpled .308 bullets will fly about 80 fps faster than normal .308 bullets. With the large .338-caliber projectiles, the difference is even greater… we can pick up nearly 150 fps.” Given the observed velocity gains achieved with dimpled bullets, Aberdeen designers are now working on dimpled shell casings for larger artillery projectiles.
Dimpled Jacket Delivers ‘Explosive’ Fragmentation
While the internal design and core materials of the new dimpled bullet remain classified, the design team revealed that the terminal performance of the new bullet has been “spectacular”. The bullet penetrates like a FMJ but then explosively fragments, resulting in a devastating energy release in the target. According to Capt. Jack Sarazen, an Aberdeen engineer, “the enhanced terminal performance of the dimpled bullet was unanticipated. This was a serendipitous effect of the slight thinning of the jacket material where the dimples are pressed.” Sarazen explained: “Most FMJ bullets break along the cannelure and then fragment into two or three large pieces. With the dimpled bullets, you have multiple fragmentation points so the bullet literally blows up like a grenade in the target.”
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August 30th, 2008
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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