June 20th, 2017

Tangent vs. Secant vs. Hybrid — Bullet Ogive Geometry Explained

Secant and Tangent Ogive Bryan LitzWe know many of our readers aren’t 100% clear on the difference between a secant ogive bullet and a tangent ogive bullet. Add the “blended” or “hybrid” ogive into the design equation and you add to the confusion. In this article, Berger Ballistician Bryan Litz, explains the characteristics of the three popular ogive types: tangent, secant, and hybrid.

In discussions of ballistics, you’ll see references to “tangent” and “secant” bullet shapes. 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 vs. Secant 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 bullet 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.”

hybrid bullet

Ogive Metrics and Rt/R Ratio
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.

Berger Hybrid bullet, .308 30 CaliberHybrid Bullet Design — Best of Both Worlds?
Bryan Litz has developed 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 mere .003″ seating depth change “makes a difference”. In an effort to produce more forgiving high-BC bullets, Bryan Litz developed the hybrid tangent/secant bullet shape.

Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths

Story sourced by Edlongrange.
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June 10th, 2015

Berger Unveils New 6.5mm 130gr AR Hybrid Tactical Bullet

Berger Bullets AR Hybrid 130gr 130 grain OTM Tactical mag-length bullet

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.

65 130 AR Hybrid Ballistic Performance

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. 65 130 AR Hybrid Cartridge ComparisonProportionally 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.

65 130 AR Hybrid Ballistic Performance

*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.

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October 28th, 2014

Ogive No Jive — Litz Explains Tangent, Secant, and Hybrid Ogives

Secant and Tangent Ogive Bryan LitzIn 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 vs. Secant 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 bullet 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.”

hybrid bullet

Ogive Metrics and Rt/R Ratio
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.

Berger Hybrid bullet, .308 30 CaliberHybrid Bullet Design — Best of Both Worlds?
Bryan Litz has developed 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 mere .003″ seating depth change “makes a difference”. In an effort to produce more forgiving high-BC bullets, Bryan Litz developed the hybrid tangent/secant bullet shape.

Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths

Story sourced by Edlongrange.

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December 29th, 2013

Bryan Litz Talks — How to Get Best Results with Berger Hybrids

2013 SHOT Show Las VegasSHOT Show 2014 kicks off in two weeks in Las Vegas. While at SHOT Show next month, we plan to get the “inside scoop” on new bullet designs from Berger, Hornady, Lapua, Nosler and Sierra.

At SHOT Show 2012 we chatted with Berger Ballistician Bryan Litz about Berger’s popular line of Hybrid bullets. Berger now offers a wide range of Hybrids in multiple calibers and weights. In fact, for .30-Caliber shooters, Berger now offers seven different Hybrid match bullets, with weights from 155 grains up to 230 grains. Two .338-caliber OTM Tactical Hybrids were introduced in 2012 (a 250-grainer and a 300-grainer).

Bryan tells us: “The hybrid design is Berger’s solution to the age old problem of precision vs. ease of use. This design is making life easier for handloaders as well as providing opportunities for commercial ammo loaders who need to offer a high performance round that also shoots precisely in many rifles with various chamber/throat configurations.”

For those not familiar with Hybrid bullets, the Hybrid design blends two common bullet nose shapes on the front section of the bullet (from the tip to the start of the bearing surface). Most of the curved section of the bullet has a Secant (VLD-style) ogive for low drag. This then blends in a Tangent-style ogive curve further back, where the bullet first contacts the rifling. The Tangent section makes seating depth less critical to accuracy, so the Hybrid bullet can shoot well through a range of seating depths, even though it has a very high Ballistic Coefficient (BC).

In the video we asked Bryan for recommended seating depths for 7mm and .30-Caliber Hybrid bullets. Bryan advises that, as a starting point, Hybrid bullets be seated .015″ (fifteen thousandths) off the lands in most barrels. Watch the video for more tips how to optimize your loads with Hybrid bullets.

Berger Hybrid Bullet

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January 23rd, 2013

New 6.5mm Scenar Ls from Lapua — .30-Caliber Ls Coming Soon

Lapua Scenar L BulletsAt SHOT Show 2013, Lapua announced it was expanding its line-up of Scenar L projectiles to include two new 6.5mm bullets and three new .30-caliber Scenar Ls. We applaud this news. This Editor has tested 6mm Scenar L bullets in his own rifles, and they have proven to be some of the most consistent bullets we have ever measured. The Scenar Ls also shot great in 8-twist barrels from Brux, Krieger, and PacNor.

Two New 6.5mm Scenar Ls
Guys with .260 Rem, 6.5×47, 6.5 Creedmoor, and 6.5-284 rifles have been eagerly awaiting the new 6.5mm Scenar Ls. These will be offered in two weights: 120 grains and 136 grains.

Scenar Ls in .30 Caliber
Lapua will release three new .30-Caliber Scenar L bullets. Along with a new 155gr Palma bullet (GB 552), Lapua will offer a 175gr Scenar L (GB 550), plus a 220gr heavy-weight Scenar L (GB 551). In magnum and short magnum chamberings, the 220-grainers should prove very effective in Long Range comps.

What Makes the Scenar Ls So Good
While all Lapua Scenar bullets are made to exacting standards, Lapua “raised the bar” with its Scanar L series. Scenar L bullets feature closer weight tolerances, tighter jacket wall concentricity standards, and greater uniformity in every dimension. Building bullets this good isn’t easy — you have to get everything right — from the gilding metal cup, to the lead wire and jacket forming, core-jacket assembly, and finally boat-tail pressing and nose-tipping. To build L-series bullets to such high standards, Lapua had to adopt new manufacturing procedures, and install proprietary new machines and advanced instrumentation never seen before in bullet production. Lapua also took its already high quality control standards and kicked them up a notch.

Lapua Scenar L BulletsNew 6.5mm Scenar Ls — First Look
At SHOT Show, Lapua unveiled its much-awaited new 6.5mm (.264 caliber) Lapua Scenar L bullets. There are two (2) new 6.5mm Scenar Ls: a 120gr tangent ogive design and a 136gr multi-ogive design. These are both all-new bullets, though the new 120gr Scenar L bears a “family resemblance” to the current (and very accurate) 123gr standard Scenar. One look at the new 136-grainer, and you can see that this is NOT just a “tweak” of the popular 139gr standard Scenar. The new 136gr Scenar L has a streamlined secant-ogive shape that blends into a more conventional tangent ogive as the bullet approaches full diameter. This dual-ogive design enhances the bullet’s BC, making it more slippery. That should translate to less drop and less drift at long range.

These new 6.5-caliber Scenar Ls should hit the market very soon. Check with Grafs.com for availability. As soon as we can get our hands on Lapua’s new 120s and 136s we will test them in a 6.5×47 Lapua bench gun and see how they perform. The .30-Cal 175gr and 220gr Scenar-Ls should arrive by late spring according to Kevin Thomas of Lapua. Kevin is a member of our Forum and he can answer your questions about the entire line-up of Lapua projectiles, along with Lapua cartridge brass.

Lapua Scenar L Bullets

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January 2nd, 2013

Berger Hybrid Bullets — What You Need to Know

2013 SHOT Show Las VegasSHOT Show 2013 kicks off in two weeks in Las Vegas. One of our top priorities is to talk with the bullet makers from Berger, Hornady, Lapua, and Nosler.

At SHOT Show 2012 we chatted with Berger Ballistician Bryan Litz about Berger’s popular line of Hybrid bullets. Berger now offers a wide range of Hybrids in multiple calibers and weights. In fact, for .30-Caliber shooters, Berger now offers six different Hybrid match bullets, with weights from 155 grains up to 230 grains. New .338 Cal Tactical Hybrids were released in 2012 and big .375 Cal, and .408 Cal Hybrids are in the works (read more below).

Bryan tells us: “The hybrid design is Berger’s solution to the age old problem of precision vs. ease of use. This design is making life easier for handloaders as well as providing opportunities for commercial ammo loaders who need to offer a high performance round that also shoots precisely in many rifles with various chamber/throat configurations.”

For those not familiar with Hybrid bullets, the Hybrid design blends two common bullet nose shapes on the front section of the bullet (from the tip to the start of the bearing surface). Most of the curved section of the bullet has a Secant (VLD-style) ogive for low drag. This then blends in a Tangent-style ogive curve further back, where the bullet first contacts the rifling. The Tangent section makes seating depth less critical to accuracy, so the Hybrid bullet can shoot well through a range of seating depths, even though it has a very high Ballistic Coefficient (BC).

In the video we asked Bryan for recommended seating depths for 7mm and .30-Caliber Hybrid bullets. Bryan advises that, as a starting point, Hybrid bullets be seated .015″ (fifteen thousandths) off the lands in most barrels. Watch the video for more tips how to optimize your loads with Hybrid bullets.

Berger Hybrid Bullet

Berger is Developing New Large-Caliber and Hunting Hybrids
In related news, Berger announced that it will be offering a series of .338-caliber Hybrids. First Berger is reintroducing the Gen 1 .338 Cal, 300gr Hybrid bullet in Berger’s Hunting line. Berger will also be making a 250gr Hybrid Hunting bullet using the same type of jacket as the original Gen 1 300gr Hybrid bullet. In addition, Berger has released a .338 Cal 250gr Match Hybrid OTM Tactical bullet, along with a 300gr Match Hybrid OTM Tactical projectile.

More big bullets are on the drawing board. Our source says “.375 Caliber and then .408 Caliber are the next new calibers to be made at Berger”. These are in the design phase, and Berger needs to build a new machine, so the .375s and .408s will not be available until 2013 at the earliest.

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May 1st, 2012

Redding Offers Retro-Fit Micrometer Stems for Standard Seaters

Redding Seating Stem MicrometerThey have been on the market for nearly a year, but you may not know that Redding sells a line of Micrometer Seater assemblies, which can be used to upgrade Redding’s standard ½-20 thread seater dies. These replacements allow you to enjoy the ease-of-use and precision of a micrometer seater, without buying a whole new die. Redding states that “the new Bullet Seating Micrometers are a direct [retro-fit] replacement for the original seating plugs and can easily be changed from one die to another.” Unfortunately, these add-on micrometer stems haven’t started shipping yet, and Redding has not provided a firm delivery date (or price). We are hoping the products will start arriving by mid-summer.

Redding Seating Stem Micrometer

NOTE: the seater assemblies are a component of the bullet seating die. These are not the dies themselves. It is the top portion of the die that contains the plunger, which pushes the bullet into the case. And here is something important: these new Bullet Seating Micrometers are available for both traditional tangent ogive bullet shapes as well as for VLD (secant ogive) bullets.

Redding Seating Stem MicrometerThat’s right, Redding now offers micrometer seater assemblies made specifically for Berger VLD bullets. These Seating Micrometers allow you to convert a standard seater to a Micrometer seater optimized for VLDs. That’s great news for VLD fans. Eric Stecker of Berger Bullets tells us: “We have confirmed with Redding that each of the new micrometer plugs in the VLD group were designed based on Berger VLD bullets. We provided all of our VLD bullets to Redding, from which they took deliberate measurements and made these new plugs.”

New VLD-specific Seater Stems Improve Bullet Seating Depth Consistency
Stecker explains how the new VLD-specific seater assemblies produce better, more accurate ammo: “Many shooters have problems getting the VLD bullets to shoot because of the bullet seater die they are using. VLD bullet noses are so long and sharp that, in many dies, the bullet tip bottoms out in the bullet seater stem instead of touching on the side of the ogive like it should. Seating depth inconsistencies up to .025″ can occur if the seater stem bottoms out on the bullet tip. The worst part is that many shooters have no idea that this is the root cause of their poor performance. This new product can help turn a frustrating shooting experience into an enjoyable one.”

Story tip from Edlongrange. We welcome submissions from our readers.
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