November 19th, 2018

Bullet Pointing 101 — How to Point Match Bullet Tips

Berger Bullet Pointing Applied Ballistics Bryan Litz Whidden Pointing Die pointer

Tech Tip by Doc Beech, Applied Ballistics Support Team
I am going to hit on some key points when it comes to bullet pointing. How much pointing and trimming needed is going to depend on the bullet itself. Specifically how bad the bullets are to begin with. Starting out with better-quality projectiles such as Bergers is going to mean two things. First that you don’t need to do as much correction to the meplat, but also that the improvement is going to be less. NOTE: We recommend you DO NOT POINT hunting bullets. Pointing can affect terminal performance in a bad way.

NOTE the change in the bullet tip shape and hollowpoint size after pointing:
Berger Bullet Pointing Applied Ballistics Bryan Litz Whidden Pointing Die pointer

Don’t Over-Point Your Bullets
What is important here is that you never want to over-point. It is far better to be safe, and under-point, rather than over-point and crush the tips even the slightest bit. To quote Bryan Litz exactly: “Best practice is to leave a tiny air gap in the tip so you’re sure not to compress the metal together which will result in crushing. Most of the gain in pointing is taking the bullet tip down to this point. Going a little further doesn’t show on target”. So in essence you are only bringing the tip down a small amount… and you want to make sure you leave an air gap at the tip.

Salazar Whidden Bullet Pointer system

Also keep in mind, bullet pointing is one of those procedures with variable returns. If you only shoot at 100-200 yards, bullet pointing will likely not benefit you. To see the benefits, which can run from 2 to 10% (possibly more with poorly designed bullets), you need be shooting at long range. Bryan says: “Typically, with pointing, you’ll see 3-4% increase in BC on average. If the nose is long and pointy (VLD shape) with a large meplat, that’s where pointing has the biggest effect; up to 8% or 10%. If the meplat is tight on a short tangent nose, the increase can be as small as 1 or 2%.” For example, If you point a Berger .308-caliber 185gr Juggernaut expect to only get a 2% increase in BC.

Berger Bullet Pointing Applied Ballistics Bryan Litz Whidden Pointing Die pointer

Should You Trim after Pointing?
Sometimes you can see tiny imperfections after pointing, but to say you “need” to trim after pointing is to say that the small imperfections make a difference. Bryan Litz advises: “If your goal is to make bullets that fly uniformly at the highest levels, it may not be necessary to trim them.” In fact Bryan states: “I’ve never trimmed a bullet tip, before or after pointing”. So in the end it is up to you to decide.

Pointing is Easy with the Right Tools
The process of pointing in itself is very simple. It takes about as much effort to point bullets as it does to seat bullets. We are simply making the air gap on the tip of the bullet ever-so smaller. Don’t rush the job — go slow. Use smooth and steady pressure on the press when pointing bullets. You don’t want to trap air in the die and damage the bullet tip. You can use most any press, with a caliber-specific sleeve and correct die insert. The Whidden pointing die has a micrometer top so making adjustments is very easy.

Bryan Litz actually helped design the Whidden Bullet Pointing Die System, so you can order the Pointing Die and Inserts directly from Applied Ballistics. Just make sure that you pick up the correct caliber sleeve(s) and appropriate insert(s). As sold by Applied Ballistics, the Whidden Bullet Pointing Die System comes with the die, one tipping insert, and one caliber-specific sleeve. To see which insert(s) you need for your bullet type(s), click this link:

LINK: Whidden Gunworks Pointing Die Insert Selection Chart

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November 12th, 2018

Optics Expertise: MIL and MOA Terminology Defined

Mil MOA reticle ranging PRS tactical minute angle precision rifle series
Visit PrecisionRifleBlog.com for a discussion of MIL vs. MOA.

Many guys getting started in long range shooting are confused about what kind of scope they should buy — specifically whether it should have MIL-based clicks or MOA-based clicks. Before you can make that decision, you need to understand the terminology. This article, with a video by Bryan Litz, explains MILS and MOA so you can choose the right type of scope for your intended application.

This March-FX 5-40x56mm Tactical FFP scope features 0.05 MIL Clicks.
Mil MOA reticle ranging PRS tactical minute angle precision rifle series

You probably know that MOA stands for “Minute of Angle” (or more precisely “minute of arc”), but could you define the terms “Milrad” or “MIL”? In his latest video, Bryan Litz of Applied Ballitics explains MOA and MILs (short for “milliradians”). Bryan defines those terms and explains how they are used. One MOA is an angular measurement (1/60th of one degree) that subtends 1.047″ at 100 yards. One MIL (i.e. one milliradian) subtends 1/10th meter at 100 meters; that means that 0.1 Mil is one centimeter (1 cm) at 100 meters. Is one angular measurement system better than another? Not necessarily… Bryan explains that Mildot scopes may be handy for ranging, but scopes with MOA-based clicks work just fine for precision work at known distances. Also because one MOA is almost exactly one inch at 100 yards, the MOA system is convenient for expressing a rifle’s accuracy. By common parlance, a “half-MOA” rifle can shoot groups that are 1/2-inch (or smaller) at 100 yards.

What is a “Minute” of Angle?
When talking about angular degrees, a “minute” is simply 1/60th. So a “Minute of Angle” is simply 1/60th of one degree of a central angle, measured either up and down (for elevation) or side to side (for windage). At 100 yards, 1 MOA equals 1.047″ on the target. This is often rounded to one inch for simplicity. Say, for example, you click up 1 MOA (four clicks on a 1/4-MOA scope). That is roughly 1 inch at 100 yards, or roughly 4 inches at 400 yards, since the target area measured by an MOA subtension increases with the distance.

one MOA minute of angle diagram

MIL vs. MOA for Target Ranging
MIL or MOA — which angular measuring system is better for target ranging (and hold-offs)? In a recent article on his PrecisionRifleBlog.com website, Cal Zant tackles that question. Analyzing the pros and cons of each, Zant concludes that both systems work well, provided you have compatible click values on your scope. Zant does note that a 1/4 MOA division is “slightly more precise” than 1/10th mil, but that’s really not a big deal: “Technically, 1/4 MOA clicks provide a little finer adjustments than 1/10 MIL. This difference is very slight… it only equates to 0.1″ difference in adjustments at 100 yards or 1″ at 1,000 yards[.]” Zant adds that, in practical terms, both 1/4-MOA clicks and 1/10th-MIL clicks work well in the field: “Most shooters agree that 1/4 MOA or 1/10 MIL are both right around that sweet spot.”

READ MIL vs. MOA Cal Zant Article.

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October 29th, 2018

Hybrid Bullets: How to Optimize Your Seating Depths

Berger Hybrid Bullet

SHOT Show 2017 kicks off in thre 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.

A while back, 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 many seven (7) 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.

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October 23rd, 2018

Great Book: Modern Advancements in Long Range Shooting Vol. 2

Bryan Litz Applied Ballistics Modern Advancements Volume 2 II testing pre-order

If you buy one book about Long Range Shooting, this should be it. Based on sophisticated testing and research, this 356-page hardcover from Applied Ballistics offers important insights you won’t find anywhere else. Modern Advancements in Long Range Shooting – Volume II, the latest treatise from Bryan Litz, is chock full of information, much of it derived through sophisticated field testing. As Chief Ballistician for Berger Bullets (and a trained rocket scientist), author Bryan Litz is uniquely qualified. Bryan is also an ace sling shooter and a past F-TR National Champion. Moreover, Bryan’s company, Applied Ballistics, has been a leader in the Extreme Long Range (ELR) discipline.

AUDIO FILE: Bryan Litz Talks about Modern Advancements in Long Range Shooting, Volume 2. (Sound file loads when you click button).

Volume II of Modern Advancements in Long Range Shooting ($39.95) contains all-new content derived from research by Applied Ballistics. Author Bryan Litz along with contributing authors Nick Vitalbo and Cal Zant use the scientific method and careful testing to answer important questions faced by long range shooters. In particular, this volume explores the subject of bullet dispersion including group convergence. Advanced hand-loading subjects are covered such as: bullet pointing and trimming, powder measurement, flash hole deburring, neck tension, and fill ratio. Each topic is explored with extensive live fire testing, and the resulting information helps to guide hand loaders in a deliberate path to success. The current bullet library of measured G1 and G7 ballistic coefficients is included as an appendix. This library currently has data on 533 bullets in common use by long range shooters.

Bryan tells us that one purpose of this book is to dispel myths and correct commonly-held misconceptions: “Modern Advancements in Long Range Shooting aims to end the misinformation which is so prevalent in long range shooting. By applying the scientific method and taking a Myth Buster approach, the state of the art is advanced….”

Bullet Dispersion and Group Convergence
Bryan Litz Applied Ballistics Modern Advancements Volume 2 II testing pre-order

Part 1 of this Volume is focused on the details of rifle bullet dispersion. Chapter 1 builds a discussion of dispersion and precision that every shooter will benefit from in terms of understanding how it impacts their particular shooting application. How many shots should you shoot in a group? What kind of 5-shot 100 yard groups correlate to average or winning precision levels in 1000 yard F-Class shooting?

Chapter 2 presents a very detailed investigation of the mysterious concept of group convergence, which is the common idea that some guns can shoot smaller (MOA) groups at longer ranges. This concept is thoroughly tested with extensive live fire, and the results answer a very important question that has baffled shooters for many generations.

Bryan Litz Applied Ballistics Modern Advancements Volume 2 II testing pre-orderPart 2 of this Volume is focused on various aspects of advanced hand-loading. Modern Advancements (Vol. II) employs live fire testing to answer the important questions that precision hand loaders are asking. What are the best ways to achieve MVs with low ES and SD? Do flash hole deburring, neck tension, primer selection, and fill ratio and powder scales sensitivity make a difference and how much? All of these questions are explored in detail with a clear explanation of test results.

One of the important chapters of Part 2 examines bullet pointing and trimming. Applied Ballistics tested 39 different bullet types from .224 through .338 caliber. Ten samples of each bullet were tested for BC in each of the following configurations: original out of the box, pointed, trimmed, pointed and trimmed. The effect on the average BC as well as the uniformity in BC was measured and tabulated, revealing what works best.

Part 3 covers a variety of general research topics. Contributing author Nick Vitalbo, a laser technology expert, tested 22 different laser rangefinders. Nick’s material on rangefinder performance is a landmark piece of work. Nick shows how shooters can determine the performance of a rangefinder under various lighting conditions, target sizes, and reflectivities.

Chapter 9 is a thorough analysis of rimfire ammunition. Ballistic Performance of Rifle Bullets, 2nd Edition presented live fire data on 95 different types of .22 rimfire ammunition, each tested in five different barrels having various lengths and twist rates. Where that book just presented the data, Chapter 9 of this book offers detailed analysis of all the test results and shows what properties of rimfire ammunition are favorable, and how the BCs, muzzle velocities and consistency of the ammo are affected by the different barrels.

Chapter 10 is a discussion of aerodynamic drag as it relates to ballistic trajectory modeling. You will learn from the ground up: what an aerodynamic drag model is, how it’s measure and used to predict trajectories. Analysis is presented which shows how the best trajectory models compare to actual measured drop in the real world.

Finally, contributing author Cal Zant of the Precision Rifle Blog presents a study of modern carbon fiber-wrapped barrels in Chapter 11. The science and technology of these modern rifle barrels is discussed, and then everything from point of impact shift to group sizes are compared for several samples of each type of barrel including standard steel barrels.

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September 23rd, 2018

Bullet Geometry: Tangent, Secant, and Hybrid Ogives Explained

secant tangent hybrid ogive Bryan Litz Applied ballistices 200X Berger Hybrid bullet, .308 30 Caliber

In discussions of ballistics, you’ll see references to “tangent”, “secant”, and “hybrid” 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, secant, and hybrid ogive bullet designs, to help you understand the characteristics of these three basic 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.

hybrid bullet

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.”

Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths

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.

Story sourced by Edlongrange.
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September 15th, 2018

The “Mental Game” — Mantras for Competitive Shooting Success

shooting training applied ballistics bryan litz

Bryan Litz Applied Ballistics“Shoot Like a Champion”. Bryan Litz, author of Applied Ballistics for Long-Range Shooting, says he often sees notes like this tucked in shooter’s gear (or taped to an ammo box) at matches. What “marksmanship mantras” do you use? Do you have a favorite quote that you keep in mind during competition?

On the Applied Ballistics Facebook Page, Bryan invited other shooters to post the motivating words (and little reminders) they use in competition. Here are some of the best responses:


    “Shoot 10s and No One Can Catch You…” — James Crofts

    “You Can’t Miss Fast Enough to Win.” — G. Smith

    “Forget the last shot. Shoot what you see!” — P. Kelley

    “Breathe, relax, you’ve got this, just don’t [mess] up.” — S. Wolf

    “It ain’t over ’til the fat lady sings.” — J. McEwen

    “Keep calm and shoot V-Bull.” — R. Fortier

    “Be still and know that I am God[.]” (PS 46:10) — D.J. Meyer

    “Work Hard, Stay Humble.” — J. Snyder

    “Shoot with your mind.” — K. Skarphedinsson

    “The flags are lying.” — R. Cumbus

    “Relax and Breathe.” — T. Fox

    “Zero Excuses.” — M. Johnson

    “SLOW DOWN!” — T. Shelton

    “Aim Small.” — K. Buster

    “Don’t Forget the Ammo!” (Taped on Gun Case) — Anonymous

PARTING SHOT: It’s not really a mantra, but Rick Jensen said his favorite quote was by gunsmith Stick Starks: “Them boys drove a long ways to suck”. Rick adds: “I don’t want to be that guy”, i.e. the subject of that remark.

Permalink Competition, Shooting Skills 1 Comment »
September 8th, 2018

F-TR Tech — the Low-Profile Solution Pioneered by Pierce

F-TR Scoville Stock F-Class Rifle

One recent trend in F-TR competition is the use of low-profile, benchrest-type stocks shot with a light hand-hold and little or no face contact. For this method of F-TR shooting to work, you need the right equipment, and practice a “minimalist” shooting technique. One of the pioneers in this style of F-TR shooting is action-maker John Pierce of Pierce Engineering. Above you can see John shooting one of his F-TR rifles at the 2015 Canadian F-Class Championships. Note the straight-line stock and see how the adjustable bipod is set quite low to the ground (in fact the bipod’s arms are almost straight out).

F-TR Scoville Stock F-Class Rifle

Members of the Michigan F-TR Team, including Bryan Litz, have used similar rigs with success. Bryan said it took a while to adapt his shooting technique to this kind of rig, but there is a pay-off. Armed with a Pierce-built F-TR rifle, Bryan won his first-ever F-TR Match. Bryan explains the technique he uses when shooting this kind of rifle:

“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 [with high X-Count by a large margin]. 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 discipline.”

Bryan’s Pierce-built F-TR rig is a tack-driver: “I can certainly vouch for this set-up! In [a 2015] mid-range State Championship in Midland, MI, I shot my Pierce rifle into first place with a 598-44X (20 shots at 300, 500 and 600). Once you get used to the positioning and way of shooting these rifles, they just pour shots through the center of the target.”

Pierce F-TR Rifles with Scoville Stocks
Shown below are three complete Pierce F-TR rifles, along with a barreled action for comparison. The carbon-fiber/composite stocks are built by Bob Scoville. These Scoville stocks are very light, yet very strong and very stiff.

F-TR Scoville Stock F-Class Rifle

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August 31st, 2018

Cartridge Base to Ogive (CBTO) Length — Factors to Consider

chamber length loading berger bullets
Here are two different bullet types, 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 rifling.

Berger Bullets COAL length cartridgeEffects 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.
chamber length loading berger bullets

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.

Benefits of Having a Uniform CBTO
There is another aspect to knowing your CBTO when checking your COAL as it pertains to performance. With good bullets, tooling, and carefully-prepared cases you can easily achieve a CBTO that varies less than +/- .001″ but your COAL can vary as much as .025″ extreme spread (or more with other brands). This is not necessarily bad and it is much better than the other way around. If you have a CBTO dimension that varies but your COAL dimension is tight (within +/- .002″) then it is most likely that your bullet is bottoming out inside the seater cone on the bullet tip. This is very bad and is to be avoided. It is normal for bullets to have precisely the same nose shape and it is also normal for these same bullets to have nose lengths that can vary as much as .025″.

Summary of Cartridge Base To Ogive (CBTO) Discussion
Here are four important considerations regarding bullet seating depth as it relates to CBTO:

1. CBTO is a critical measurement to understand for handloaders because it’s directly related to precision potential, and you control it by simply setting bullet seating depth.

2. Tools and methods for measuring CBTO vary. Most of the measurement techniques have pitfalls (which may give rise to inconsistent results) that you should understand before starting out.

3. A CBTO that produces the best precision in your rifle may not produce the best precision in someone else’s rifle. Even if you have the same rifle, same bullets, same model of comparator gauges, etc. It’s possible that the gauges are not actually the same, and measurements from one don’t translate to the same dimension for another.

4. Once you find the CBTO that produces the best precision in your rifle, it’s important to allow minimal variation in that dimension when producing quality handloads. This is achieved by using quality bullets, tooling, and properly preparing case mouths and necks for consistent seating.

CLICK HERE to Read Full Article with More Info
Article sourced by EdLongrange. We welcome tips from readers.
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August 12th, 2018

How to Calculate Bullet RPM — Spin Rates and Stability

Spin rate stability bullet speed RPM Formula stabilization barrel twist
Photo by Werner Mehl, www.kurzzeit.com, all rights reserved.

Most serious shooters can tell you the muzzle velocity (MV) of their ammunition, based on measurements taken with a chronograph, or listed from a manufacturer’s data sheet. (Of course, actual speed tests conducted with YOUR gun will be more reliable.)

Bullet RPM = MV X 720/Twist Rate (in inches)

However, if you ask a typical reloader for the rotational rate of his bullet, in revolutions per minute (RPM), chances are he can’t give you an answer.

Knowing the true spin rate or RPM of your bullets is very important. First, spin rate, or RPM, will dramatically affect the performance of a bullet on a game animal. Ask any varminter and he’ll tell you that ultra-high RPM produces more dramatic hits with more “varmint hang time”. Second, RPM is important for bullet integrity. If you spin your bullets too fast, this heats up the jackets and also increases the centrifugal force acting on the jacket, pulling it outward. The combination of heat, friction, and centrifugal force can cause jacket failure and bullet “blow-ups” if you spin your bullets too fast.

Accuracy and RPM
Additionally, bullet RPM is very important for accuracy. Nearly all modern rifles use spin-stablized bullets. The barrel’s rifling imparts spin to the bullet as it passes through the bore. This rotation stabilizes the bullet in flight. Different bullets need different spin rates to perform optimally. Generally speaking, among bullets of the same caliber, longer bullets need more RPM to stabilize than do shorter bullets–often a lot more RPM.

It is generally believed that, for match bullets, best accuracy is achieved at the minimal spin rates that will fully stabilize the particular bullet at the distances where the bullet must perform. That’s why short-range 6PPC benchrest shooters use relatively slow twist rates, such as 1:14″, to stabilize their short, flatbase bullets. They could use “fast” twist rates such as 1:8″, but this delivers more bullet RPM than necessary. Match results have demonstrated conclusively that the slower twist rates produce better accuracy with these bullets.

On the other hand, Research by Bryan Litz of Applied Ballistics has shown that with long, boat-tailed bullets, best accuracy may be achieved with twist rates slightly “faster” than the minimum required for stabilization. The reasons for this are somewhat complex — but it’s something to consider when you buy your next barrel. If, for example, the bullet-maker recommends a 1:8.25″ twist, you might want to get a true 1:8″-twist barrel.

Calculating Bullet RPM from MV and Twist Rate
The lesson here is that you want to use the optimal RPM for each bullet type. So how do you calculate that? Bullet RPM is a function of two factors, barrel twist rate and velocity through the bore. With a given rifling twist rate, the quicker the bullet passes through the rifling, the faster it will be spinning when it leaves the muzzle. To a certain extent, then, if you speed up the bullet, you can use a slower twist rate, and still end up with enough RPM to stabilize the bullet. But you have to know how to calculate RPM so you can maintain sufficient revs.

Bullet RPM Formula
Here is a simple formula for calculating bullet RPM:

MV x (12/twist rate in inches) x 60 = Bullet RPM

Quick Version: MV X 720/Twist Rate = RPM

Example One: In a 1:12″ twist barrel the bullet will make one complete revolution for every 12″ (or 1 foot) it travels through the bore. This makes the RPM calculation very easy. With a velocity of 3000 feet per second (FPS), in a 1:12″ twist barrel, the bullet will spin 3000 revolutions per SECOND (because it is traveling exactly one foot, and thereby making one complete revolution, in 1/3000 of a second). To convert to RPM, simply multiply by 60 since there are 60 seconds in a minute. Thus, at 3000 FPS, a bullet will be spinning at 3000 x 60, or 180,000 RPM, when it leaves the barrel.

Example Two: What about a faster twist rate, say a 1:8″ twist? We know the bullet will be spinning faster than in Example One, but how much faster? Using the formula, this is simple to calculate. Assuming the same MV of 3000 FPS, the bullet makes 12/8 or 1.5 revolutions for each 12″ or one foot it travels in the bore. Accordingly, the RPM is 3000 x (12/8) x 60, or 270,000 RPM.

Implications for Gun Builders and Reloaders
Calculating the RPM based on twist rate and MV gives us some very important information. Number one, we can tailor the load to decrease velocity just enough to avoid jacket failure and bullet blow-up at excessive RPMs. Number two, knowing how to find bullet RPM helps us compare barrels of different twist rates. Once we find that a bullet is stable at a given RPM, that gives us a “target” to meet or exceed in other barrels with a different twist rate. Although there are other important factors to consider, if you speed up the bullet (i.e. increase MV), you MAY be able to run a slower twist-rate barrel, so long as you maintain the requisite RPM for stabilization and other factors contributing to Gyroscopic Stability are present. In fact, you may need somewhat MORE RPM as you increase velocity, because more speed puts more pressure, a destabilizing force, on the nose of the bullet. You need to compensate for that destabilizing force with somewhat more RPM. But, as a general rule, if you increase velocity you CAN decrease twist rate. What’s the benefit? The slower twist-rate barrel may, potentially, be more accurate. And barrel heat and friction may be reduced somewhat.

Just remember that as you reduce twist rate you need to increase velocity, and you may need somewhat MORE RPM than before. (As velocities climb, destabilizing forces increase somewhat, RPM being equal.) There is a formula by Don Miller that can help you calculate how much you can slow down the twist rate as you increase velocity.

CLICK HERE for Miller Formula in Excel Spreadsheet Format

That said, we note that bullet-makers provide a recommended twist rate for their bullets. This is the “safe bet” to achieve stabilization with that bullet, and it may also indicate the twist rate at which the bullet shoots best. Though the RPM number alone does not assure gyroscopic stability, an RPM-based calculation can be very useful. We’ve seen real world examples where a bullet that needs an 8-twist barrel at 2800 FPS MV, would stabilize in a 9-twist barrel at 3200 FPS MV. Consider these examples.

MV = 2800 FPS
8-Twist RPM = 2800 x (12/8) x 60 = 252,000 RPM

MV = 3200 FPS
9-Twist RPM = 3200 x (12/9) x 60 = 256,000 RPM

Of course max velocity will be limited by case capacity and pressure. You can’t switch to a slower twist-rate barrel and maintain RPM if you’ve already maxed out your MV. But the Miller Formula can help you select an optimal twist rate if you’re thinking of running the same bullet in a larger case with more potential velocity.

Permalink Bullets, Brass, Ammo, Tech Tip No Comments »
August 11th, 2018

G1 vs. G7 Ballistic Coefficient Models — What You Need to Know

G1 G7 BC drag models

Over the past 12 months, this article was one of the TOP TEN most-read Daily Bulletin features. We’re reprising it today for those who may have missed it the first time. The above diagram comes from a TiborasurasRex YouTube Video comparing G1 and G7 BC models. CLICK HERE to watch the video.

The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.

Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”

The simple answer is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.

G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferrable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.

G1 G7 Ballistic coefficients

Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, 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’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:

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, according to Bryan.

[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.]

Permalink Bullets, Brass, Ammo, Reloading No Comments »
July 30th, 2018

Get Smart — Read FREE Applied Ballistics TECH Articles

Want to improve your understanding of Ballistics, Bullet Design, Bullet Pointing, and other shooting-related tech topics? Well here’s a treasure trove of gun expertise. Applied Ballistics offers three dozen FREE tech articles on its website. Curious about Coriolis? — You’ll find answers. Want to understand the difference between G1 and G7 BC? — There’s an article about that.

“Doc” Beech, technical support specialist at Applied Ballistics says these articles can help shooters working with ballistics programs: “One of the biggest issues I have seen is the misunderstanding… about a bullet’s ballistic coefficient (BC) and what it really means. Several papers on ballistic coefficient are available for shooters to review on the website.”

Credit Shooting Sports USA Editor John Parker for finding this great resource. John writes: “Our friends at Applied Ballistics have a real gold mine of articles on the science of accurate shooting on their website. This is a fantastic source for precision shooting information[.] Topics presented are wide-ranging — from ballistic coefficients to bullet analysis.”

READ All Applied Ballistics Articles HERE »

Here are six (6) of our favorite Applied Ballistics articles, available for FREE as PDF files. There are 31 more, all available on the Applied Ballistics Articles Webpage.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip 2 Comments »
June 23rd, 2018

Wind-Reading Tips from Champion Shooters

Shooting Sports USA

The digital archives of Shooting Sports USA magazine (SSUSA) features an Expert Forum on Wind Reading. This outstanding article on wind reading starts off with a section by ballistics guru Bryan Litz, author of Applied Ballistics for Long-Range Shooting. Then four of the greatest American shooters in history share their personal wind wisdom. Lanny Basham (Olympic Gold Medalist, author, Winning in the Wind), Nancy Tompkins (Past National HP Champion, author, Prone and Long-Range Rifle Shooting), David Tubb (11-Time Camp Perry National Champion), and Lones Wigger (Olympic Hall of Fame) all offer practical wind-reading lessons learned during their shooting careers.

CLICK HERE for Full Article in Shooting Sports USA Archive

CLICK HERE to Download Article Issue in Printable PDF Format.

Whether you shoot paper at Perry or prairie dogs in the Dakotas, this is a certified “must-read” resource on reading the wind. Here is a sample selection from the article:

Shooting Sports USA



Visit www.SSUSA.org

Shooting Sports USA magazine (SSUSA) has a modern, mobile-friendly website with tons of great content. Log on to www.ssusa.org. There you’ll find current news stories as well as popular articles from the SSUSA archives. The SSUSA website also includes match reports, gear reviews, reloading advice, plus expert marksmanship tips from the USAMU.

Permalink - Articles, Shooting Skills 5 Comments »
May 23rd, 2018

Accuracy Vs. Precision — They Are Not the Same Thing

Applied Ballistics Accuracy Precision
This image is from Modern Advancements in Long Range Shooting, Volume 2.

The next time a shooter comes up to you at the range, and says: “My rifle shoots one-third MOA all day long”, challenge him to put a first-round hit on a 1/2 MOA plate at 1000 yards. There’s a difference between shooting small groups at close range (Precision) and “on-target” Accuracy at long range.

Article by Applied Ballistics, LLC
Just how much better is a 0.5 MOA rifle vs. a 1 MOA rifle? Is it worth chasing quarter-MOA if you have half-MOA rifle? This is an important question. If you look across Facebook you will find scores of shooters posting 1/3-MOA or 1/4-MOA shot groups [usually at 100 yards]. Some of those guys are spending countless hours trying to chase that golden quarter-MOA group.

Don’t take this statement the wrong way, having a good, consistent rifle is a key to success. But accuracy is extremely important to long range shooting. Having a precision (0.5 MOA) rifle, but not having put the time in to practice accuracy (hitting a 0.5 MOA plate first shot at 1000 yards) is counter-productive. [Editor: By this, we mean that you can have a rifle capable of shooting small groups at 100 yards, but you won’t see that gun’s full potential unless you can practice and perfect the skills of long-range shooting. Successful long range shooting demands more than precision alone.]

What if, your goal was to produce 5-shot, sub-half-MOA groups at 1000 yards instead of 100 yards? Think about how much more you would be including in the learning process, especially that all-important factor: managing the wind! Here is a good article that talks about Precision vs. Accuracy: Hitting Targets at Long Range.

This is not intended to say that precision is not important; rather it is intended to show that balance is important. You can use WEZ to do your own studies on this very subject, and it might be surprising to the shooter just how much you don’t gain by chasing precision over accuracy. Two books which cover this subject really well are Accuracy and Precision for Long Range Shooting and Modern Advancements in Long Range Shooting Vol 2.

Here’s a stunning combination of Precision (small group) WITH accuracy (centered on target). Yep that’s ten shots at 1000 yards, all in the middle of the target:
Scott Nix Dasher Record

Video Demonstrates Amazing 1000-Yard Accuracy AND Precision

Watch the video. You can see the group form up, shot by shot. It’s pretty amazing. Scott’s first shot (at the 45-second mark of the video) was right in the X-Ring, and four of Scott’s first five shots were Xs. That’s drilling them!

Comments

“Accuracy with precision is the route for me. It is not an either/or game. If I have a precision rifle (0.25 MOA or less) and I practice to be accurate, then high scores will be the result — Jim Borden

“I would agree for PRS, hunting, and to a certain extent F-Class. However, for 1000-yard IBS benchrest competition, 0.5 MOA groups in good conditions will almost always loose the relay.” — James B

“Another thought is that [at 1000 yards] a 1 MOA gun with single-digit standard deviations [may] out shoot a 0.5 MOA rifle with standard deviations of 20+ fps.” — Beard Owens

“Both… you need both: Accuracy AND Precision. I competed in varmint matches — we shot small silhouettes at 600 yards. I started with a factory .260 Rem rifle that was 0.8 MOA on a good day. I typically hit 8-9 of 20 targets, but rarely nailed the small chickens — which had a hit zone just 4″ in diameter. I then started using a semi-custom 6mmBR rifle that could reliably deliver 1/4 MOA at 100 yards (honest). My hit count on the silhouettes zoomed to 15-18, and suddenly the chickens were going down. In that game — small targets at 600 yards — there was no substitute for precision.” — Paul McM

Permalink Competition, News, Shooting Skills 2 Comments »
May 9th, 2018

Elements of Long Range Shooting Video Series

Bryan Litz Elements Long Range Shooting NSSF Ballistics Coeffecient Atmospherics

Want to learn more about Long Range Shooting? Check out the “Elements of Long Range Shooting” videos from the National Shooting Sport Foundation (NSSF). In this multi-part series, Bryan Litz of Applied Ballistics covers a variety of topics of interest to precision shooters. Today we feature three of these videos. There are five other videos in this series. Watch the entire 8-video “Elements of Long Range Shooting” series on the NSSF YouTube Channel.

Litz NSSF Video Elements long range shooting Raton NM ELR

Atmospherics and Density Altitude

Bryan Litz explains: “An important element in calculating an accurate firing solution for long-range shooting is understanding the effects of atmospherics on a projectile.” Atmospherics include air pressure, air temperature, and humidity. Bryan notes: “Temperature, pressure, and humidity all affect the air density… that the bullet is flying through. You can combine all those factors into one variable called ‘Density Altitude’.” Density Altitude is used by the ballistic solver to account for air density variables that affect bullet flight.

Bullet Ballistic Coefficients

A bullet’s ballistic coefficient (BC) basically expresses how well the bullet flies through the air. Higher BC bullets have less aerodynamic drag than lower BC projectiles. You will see BCs listed as either G1 and G7 numbers. These correspond to different bullet shape models. Generally speaking, the G7 model works better for the long, boat-tail bullets used for long-range shooting. Notably, a bullet’s drag is NOT constant in flight. The true BC can vary over the course of the trajectory as the bullet velocity degrades. In other words, “BC is dynamic”. That said, you can make very accurate drop charts using the BCs provided by major bullet-makers, as plugged into solvers. However, long-range competitors may want to record “real world” drop numbers at various distances. For example, we’ve seen trajectories be higher than predicted at 500 yards, yet lower than predicted at 1000.

Ballistics Solvers — Many Options

Bryan Litz observes: “When we talk about the elements of long range shooting, obviously a very important element is a getting a fire solution, using a ballistic solver. There are a lot of ballistic solvers out there… Applied Ballistics has smartphone Apps. Applied Ballistics has integrated the ballistic solver directly into a Kestral, and the same solver runs (manually) on the Accuracy Solutions Wiz-Wheel. The point is, if it is an Applied Ballistics device it is running the same solutions across the board.”

About Bryan Litz
Bryan began his career as a rocket scientist, quite literally. He then started Applied Ballistics, the leading company focusing on ballistics science for rifle shooting. A past F-TR Long-Range National Champion and Chief Ballistician for Berger Bullets, knows his stuff. His Applied Ballistics squad was the winning team at the 2017 King of 2 Miles event, and Applied Ballistics recently received a major U.S. defense contract to to execute Phase 1 of the Extreme Sniper Strike Operations (ESSO) project.

Permalink - Videos, Shooting Skills, Tactical No Comments »
May 7th, 2018

New BDX Electro-Optical System Shows Hold-overs in Scope

SIG Sauer BDX ballistics Data exchange Bryan Litz Doc Beech Laser Rangefinder hold-over

SIG Sauer and Applied Ballistics showed off impressive new electro-optical technology at the NRA Show in Dallas. Bryan Litz says “SIG Sauer’s Ballistics Data Exchange (BDX) is game changer. Imagine lazing a long range target, and having your exact fire solution (hold-over) automatically projected into your scope based on your ballistic profile.”

BDX takes target range info from a SIG Sauer Laser Rangefinder, calculates a ballistic solution using Applied Ballistics software, then displays the hold-over info directly in the optic (via a wireless BlueTooth connection). Just dial and shoot. Put the calculated BDX dot on the target and shoot. This ground-breaking BDX technology enables key ballistic hold-over information to be exchanged wirelessly among BDX-enabled Electro-Optics products.

You can buy this as a package with scope and LRF, starting at just $700.00 for scope and rangefinder. To our surprise, these scopes have a normal form factor. They look completely “normal”, with no clunky receiver boxes or extra turrets. BDX riflescopes aren’t bulky or heavy even though they include built-in electronics, level, and inclination detection.

“Rangefinding riflescopes of the past have had two major shortcomings: they are either big, boxy and heavy, or extremely expensive. The … BDX system packs advanced ballistics technology into a simple platform that looks just like the rangefinder and riflescope [hunters use] today. It is extremely simple to use. Range a target, put the digital ballistic holdover dot on target, pull the trigger — just connect the dot.” — Andy York, President, SIG Sauer Electro-Optics.

SIG Sauer’s Ballistics Data Exchange (BDX) is an integrated system of devices that talk seamlessly to each other, sharing data. Applied Ballistics says this system be expanded in the months ahead. “This system will be comprised of scopes, rangefinders, binoculars, and more. BDX will even be able to ‘talk’ to Kestrels and Garmins as well as SIG Sauer smart-scopes. This is only the start, over the next year you will see increasing levels of tech becoming available.”

How BDX (Ballistics Data Exchange) Functions — Software and Hardware
How does BDX work? First download the SIG BDX App for Android or iOS. Then pair the KILO BDX rangefinder and SIERRA3BDX riflescope, and set up a basic ballistic profile. Once you are in the field, range your target as you normally would, and the KILO BDX rangefinder will utilize onboard Applied Ballistics Ultralight™ to instantly send your dope to the scope via Bluetooth. Using your basic ballistic profile, the ballistic solution is calculated for your target and will instantly illuminate on the BDX-R1 Digital Ballistic Reticle with windage and elevation holds in the SIERRA3BDX riflescope. A blue LED on the riflescope power selector indicates that the BDX system is paired, and when the reticle has received new ballistic holdover and windage data from the rangefinder.

Permalink Hunting/Varminting, New Product, Optics 1 Comment »
April 9th, 2018

Applied Ballistics Secures $1.3 Million U.S. Defense Contract

Applied Ballistics LLC CTTSO Extreme Sniper Strike Operations ESSO

We want to congratulate Bryan Litz and his talented team at Applied Ballistics LLC. We have followed Bryan’s career as a bullet designer, ballistician, author, software product developer, and ELR pioneer. His team leads the world in advancing the science of long range shooting. And it looks like all the hard work has paid off — Applied Ballistics has secured a major contract to develop extreme long-range sniper capability for the U.S. Military.

Applied Ballistics LLC, a Michigan-based tech company, has been awarded a $1,300,000 contract by the Combating Terrorism Technical Support Office (CTTSO) to execute Phase 1 of the Extreme Sniper Strike Operations (ESSO) project.

Phase 1 of the ESSO project is focused on advancing the predictive capabilities of modern ballistic solvers by performing Doppler radar measurement and modeling of current service rounds at Extreme Long Range (ELR) as a function of gyroscopic stability, and refining the models of secondary ballistic effects such as spin rate decay and spin drift at ELR. Phase 1 will conclude with the ballistic modeling enhancements being integrated into the existing Applied Ballistics ecosystem of electronic devices which are currently deployed by numerous U.S. and allied armed forces around the world. Phase 1 is scheduled for completion in late 2018.

Phase 2 of the ESSO project is a potential follow on (2019) that focuses on the development and fielding of an advanced ELR sniper rifle system designed to drastically increase first-round hit probability at ELR on man-sized targets. The Applied Ballistics Weapons Division is currently conducting research and development on weapons platforms, as well as new cartridge and bullet options, that will maximize ELR ballistic performance from lightweight, practical, magazine-fed systems.

Applied Ballistics LLC CTTSO Extreme Sniper Strike Operations ESSO

Bryan Litz, owner of Applied Ballistics LLC, said: “Our team of Aerospace, Mechanical, Electrical and Computer Science Engineers, and Technicians will apply our combined experience including years of testing and competing in ELR Shooting to the successful completion of the ESSO program objectives. This means extending the maximum effective range of U.S. and allied snipers, achieving decisive overmatch on the battlefield. I can’t imagine a better application of Applied Ballistics’ collective efforts.”

Applied Ballistics has developed ballistics software for mobile Apps. AB’s software has been integrated into numerous products including Kestrels, Laser Rangefinders, and “Smart” optics.

Applied Ballistics LLC CTTSO Extreme Sniper Strike Operations ESSO

Applied Ballistics Seminar in Utah, June 2-3, 2018

Applied Ballistics will offer a Ballistics Seminar June 2 and 3, 2018 at the Snowbird Cliff Lodge, Salt Lake City, Utah. This will include two full days of instruction with lectures plus Q&A sessions. The $625 cost of the seminar includes all 5 AB books, both AB DVD sets, AB Analytics, and Swag Bag.

CLICK HERE to Register. NOTE: Through April 17th, get $100 Off with discount code ABSEM100.

About Applied Ballistics, LLC:
Applied Ballistics’ mission is to be a complete and unbiased source of external ballistics information for long range shooters. We believe in the scientific method and promote mastery through understanding of the fundamentals. The results of our work are passed on to the government and shooting communities through clear and helpful instructional materials, as well as easy-to-use ballistic software running on many products.

Permalink News, Tactical 2 Comments »
March 23rd, 2018

Angular Measurement — Mil vs. MOA — What You Need to Know

Mil MOA reticle ranging PRS tactical minute angle precision rifle series
Visit PrecisionRifleBlog.com for a discussion of MIL vs. MOA.

Many guys getting started in long range shooting are confused about what kind of scope they should buy — specifically whether it should have MIL-based clicks or MOA-based clicks. Before you can make that decision, you need to understand the terminology. This article, with a video by Bryan Litz, explains MILS and MOA so you can choose the right type of scope for your intended application.

This March-FX 5-40x56mm Tactical FFP scope features 0.05 MIL Clicks.
Mil MOA reticle ranging PRS tactical minute angle precision rifle series

You probably know that MOA stands for “Minute of Angle” (or more precisely “minute of arc”), but could you define the terms “Milrad” or “MIL”? In his latest video, Bryan Litz of Applied Ballitics explains MOA and MILs (short for “milliradians”). Bryan defines those terms and explains how they are used. One MOA is an angular measurement (1/60th of one degree) that subtends 1.047″ at 100 yards. One MIL (i.e. one milliradian) subtends 1/10th meter at 100 meters; that means that 0.1 Mil is one centimeter (1 cm) at 100 meters. Is one angular measurement system better than another? Not necessarily… Bryan explains that Mildot scopes may be handy for ranging, but scopes with MOA-based clicks work just fine for precision work at known distances. Also because one MOA is almost exactly one inch at 100 yards, the MOA system is convenient for expressing a rifle’s accuracy. By common parlance, a “half-MOA” rifle can shoot groups that are 1/2-inch (or smaller) at 100 yards.

What is a “Minute” of Angle?
When talking about angular degrees, a “minute” is simply 1/60th. So a “Minute of Angle” is simply 1/60th of one degree of a central angle, measured either up and down (for elevation) or side to side (for windage). At 100 yards, 1 MOA equals 1.047″ on the target. This is often rounded to one inch for simplicity. Say, for example, you click up 1 MOA (four clicks on a 1/4-MOA scope). That is roughly 1 inch at 100 yards, or roughly 4 inches at 400 yards, since the target area measured by an MOA subtension increases with the distance.

one MOA minute of angle diagram

MIL vs. MOA for Target Ranging
MIL or MOA — which angular measuring system is better for target ranging (and hold-offs)? In a recent article on his PrecisionRifleBlog.com website, Cal Zant tackles that question. Analyzing the pros and cons of each, Zant concludes that both systems work well, provided you have compatible click values on your scope. Zant does note that a 1/4 MOA division is “slightly more precise” than 1/10th mil, but that’s really not a big deal: “Technically, 1/4 MOA clicks provide a little finer adjustments than 1/10 MIL. This difference is very slight… it only equates to 0.1″ difference in adjustments at 100 yards or 1″ at 1,000 yards[.]” Zant adds that, in practical terms, both 1/4-MOA clicks and 1/10th-MIL clicks work well in the field: “Most shooters agree that 1/4 MOA or 1/10 MIL are both right around that sweet spot.”

READ MIL vs. MOA Cal Zant Article.

Permalink - Articles, - Videos, Shooting Skills 4 Comments »
March 12th, 2018

FREE Bushnell Ballistics App with Applied Ballistics Software

Bushnell Applied Ballistics App iOS Android Google Play

Bushnell has released a FREE new Ballistics App powered by the Applied Ballistics Ultralite Engine. The new Bushnell Ballistics App easily calculates ballistic solutions for any popular cartridge type once you input velocity, BC, and atmospherics. The App features trusty Applied Ballistics bullet data, and it can even pull in atmospheric data from web weather sources. This allows you to calculate hold-overs and make precise wind corrections. The App is offered in both iOS and Android OS versions.

“The new Bushnell Ballistics App is powered by the Applied Ballistics Ultralite engine, the most trusted ballistics data-cruncher in the industry,” said Bushnell Marketing Manager Matt Rice. “This App allows users to easily build and modify gun profiles and build range cards to calculate firing solutions based on their specific scope and ammunition choices. All of our Bushnell scopes and reticles have been pre-loaded [in the App].”

Bushnell Applied Ballistics App iOS Android Google Play

The Bushnell App features AB Connect, a live library of G1/G7 data, plus the Applied Ballistics Bullet Library with 740+ pre-loaded bullet profiles. The Bushnell scope library features 150+ scopes and 30 reticle options. Atmospheric data can be updated manually or directly from the internet (when connected). Angle range compensation is also calculated. Gun profile management provides up to five saved profiles with reticle-based firing solutions. A multiple target feature saves up to five targets. Range cards can be shared or printed using the Email Range Card Function.

The FREE App works on both Android and iOS operating systems, and is available on Google Play and the App Store. It is optimized for Bushnell riflescopes and reticles, but is compatible with all optics. Once downloaded, the App functions off the grid — no cell service required.

“The new Bushnell Ballistic App puts the power of long-range, first-shot accuracy into the hands of any shooter,” Rice said. “it was designed to perform in any condition and to offer our consumers true value, with features that far exceed the price — which, in this case, is free!”

Permalink New Product, Shooting Skills No Comments »
February 15th, 2018

Shooting on a Spinning Planet — The Coriolis Effect

Whittington Coriolis Effect
Photo by Dustin Ellermann at Whittington Center Range.

The Coriolis Effect comes into play with extreme long-range shots like this (2100 yards at Raton, NM). The rotation of the earth actually moves the target a small distance (in space) during the long duration of the bullet’s flight.

Coriolis Effect Bryan Litz Applied BallisticsWhen you’re out at the range, the Earth seems very stable. But it is actually a big sphere zooming through space while spinning around its axis, one complete turn every 24 hours. The rotation of the earth can create problems for extreme long-range shooters. During extended bullet flight times, the rotation of the planet causes an apparent deflection of the bullet path over very long distances. This is the ballistics manifestation of the Coriolis Effect.

Bryan Litz of Applied Ballistics discusses explains the Coriolis Effect in his Ballistics Books and Seminars. Bryan notes that Coriolis is “a very subtle effect. People like to make more of it than it is because it seems mysterious.” In most common shooting situations inside 1K, Coriolis is not important. At 1000 yards, the Effect represents less than one click (for most cartridge types). Even well past 1000 yards, in windy conditions, the Coriolis Effect may well be “lost in the noise”. But in very calm conditions, when shooting at extreme ranges, Bryan says you can benefit from adjusting your ballistics solution for Coriolis.

Bryan explains: “The Coriolis Effect… has to do with the spin of the earth. You are basically shooting from one point to another on a rotating sphere, in an inertial reference frame. The consequence of that is that, if the flight time of the bullet gets significantly long, the bullet can have an apparent drift from its intended target. The amount [of apparent drift] is very small — it depends on your latitude and azimuth of fire on the planet.”

Coriolis Effect Bryan Litz Applied Ballistics

Coriolis is a very subtle effect. With typical bullet BCs and velocities, you must get to at least 1000 yards before Coriolis amounts to even one click. Accordingly, Bryan advises: “Coriolis Effect is NOT something to think about on moving targets, it is NOT something to think about in high, uncertain wind environments because there are variables that are dominating your uncertainty picture, and the Coriolis will distract you more than the correction is worth.”

“Where you could think about Coriolis, and have it be a major impact on your hit percentage, is if you are shooting at extended range, at relatively small targets, in low-wind conditions. Where you know your muzzle velocity and BC very well, [and there are] pristine conditions, that’s where you’re going to see Coriolis creep in. You’ll receive more refinement and accuracy in your ballistics solutions if you account for Coriolis on those types of shots. But in most practical long-range shooting situations, Coriolis is NOT important. What IS important is to understand is when you should think about it and when you shouldn’t, i.e. when applying it will matter and when it won’t.”

The Coriolis Effect — General Physics
The Coriolis Effect is the apparent deflection of moving objects when the motion is described relative to a rotating reference frame. The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object’s speed in the rotating frame.

A commonly encountered rotating reference frame is the Earth. The Coriolis effect is caused by the rotation of the Earth and the inertia of the mass experiencing the effect. Because the Earth completes only one rotation per day, the Coriolis force is quite small, and its effects generally become noticeable only for motions occurring over large distances and long periods of time. This force causes moving objects on the surface of the Earth to be deflected to the right (with respect to the direction of travel) in the Northern Hemisphere and to the left in the Southern Hemisphere. The horizontal deflection effect is greater near the poles and smallest at the equator, since the rate of change in the diameter of the circles of latitude when travelling north or south, increases the closer the object is to the poles. (Source: Wikipedia)

Permalink Shooting Skills, Tech Tip 3 Comments »
February 13th, 2018

Tall Target Test — How to Verify Your Scope’s True Click Values

Scope Click Verify Elevation Tall Target Bryan Litz NSSF test turret MOA MIL

Have you recently purchased a new scope? Then you should verify the actual click value of the turrets before you use the optic in competition (or on a long-range hunt). While a scope may have listed click values of 1/4-MOA, 1/8-MOA or 0.1 Mils, the reality may be slightly different. Many scopes have actual click values that are slightly higher or lower than the value claimed by the manufacturer. The small variance adds up when you click through a wide range of elevation.

In this video, Bryan Litz of Applied Ballistics shows how to verify your true click values using a “Tall Target Test”. The idea is to start at the bottom end of a vertical line, and then click up 30 MOA or so. Multiply the number of clicked MOA by 1.047 to get the claimed value in inches. For example, at 100 yards, 30 MOA is exactly 31.41 inches. Then measure the difference in your actual point of impact. If, for example, your point of impact is 33 inches, then you are getting more than the stated MOA with each click (assuming the target is positioned at exactly 100 yards).

Scope Click Verify Elevation Tall Target Bryan Litz NSSF test turret MOA MIL

How to Perform the Tall Target Test
The objective of the tall target test is to insure that your scope is giving you the proper amount of adjustment. For example, when you dial 30 MOA, are you really getting 30 MOA, or are you getting 28.5 or 31.2 MOA? The only way to be sure is to verify, don’t take it for granted! Knowing your scopes true click values insures that you can accurately apply a ballistic solution. In fact, many perceived inaccuracies of long range ballistics solutions are actually caused by the scopes not applying the intended adjustment. In order to verify your scope’s true movement and calculate a correction factor, follow the steps in the Tall Target Worksheet. This worksheet takes you thru the ‘calibration process’ including measuring true range to target and actual POI shift for a given scope adjustment. The goal is to calculate a correction factor that you can apply to a ballistic solution which accounts for the tracking error of your scope. For example, if you find your scope moves 7% more than it should, then you have to apply 7% less than the ballistic solution calls for to hit your target.


CLICK HERE to DOWNLOAD Tall Target Worksheet (PDF) »

NOTE: When doing this test, don’t go for the maximum possible elevation. You don’t want to max out the elevation knob, running it to the top stop. Bryan Litz explains: “It’s good to avoid the extremes of adjustment when doing the tall target test.I don’t know how much different the clicks would be at the edges, but they’re not the same.”

Should You Perform a WIDE Target Test Too?
What about testing your windage clicks the same way, with a WIDE target test? Bryan Litz says that’s not really necessary: “The wide target test isn’t as important for a couple reasons. First, you typically don’t dial nearly as much wind as you do elevation. Second, your dialed windage is a guess to begin with; a moving average that’s different for every shot. Whereas you stand to gain a lot by nailing vertical down to the click, the same is not true of windage. If there’s a 5% error in your scope’s windage tracking, you’d never know it.”

Scope Tall Test level calibrationVerifying Scope Level With Tall Target Test
Bryan says: “While setting up your Tall Target Test, you should also verify that your scope level is mounted and aligned properly. This is critical to insuring that you’ll have a long range horizontal zero when you dial on a bunch of elevation for long range shots. This is a requirement for all kinds of long range shooting. Without a properly-mounted scope level (verified on a Tall Target), you really can’t guarantee your horizontal zero at long range.”

NOTE: For ‘known-distance’ competition, this is the only mandatory part of the tall target test, since slight variations in elevation click-values are not that important once you’re centered “on target” at a known distance.

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