Thomas Haugland, a Shooters’ Forum member from Norway, is a long-range target shooter and hunter. He has created an interesting video showing how to gauge wind velocities by watching trees, grass, and other natural vegetation. The video commentary is in English, but the units of wind speed (and distance) are metric. Haugland explains: “This is not a full tutorial, but rather a short heads-up to make you draw the lines between the dots yourself”. Here are some conversions that will help when watching the video:
.5 m/s = 1.1 mph | 1 m/s = 2.2 mph | 2 m/s = 4.5 mph
3 m/s = 6.7 mph | 4 m/s = 8.9 mph | 5 m/s =11.2 mph
With the Berger Southwest Nationals coming up soon (Feb. 6-12), we thought we would share some tips from a past Champion who really knows the Ben Avery range in Phoenix. In 2015, Bryan won the F-TR Mid-Range AND Long-Range National Championships hosted at Ben Avery. And at the 2014 Berger SW Nationals (SWN), Bryan took top honors among all sling shooters. If you only know Bryan Litz from his Applied Ballistics Books and DVDs, you may not realize that this guy is a great marksman (along with being an actual rocket scientist). This guy can shoot.
Given his impressive track record at Ben Avery, we asked Bryan if he had any advice for other long-range competitors. First Bryan provided three tips concerning Ballistics, his special area of expertise. Next Bryan offered three more general tips about long-range competition — how to analyze your shooting, how to choose your ‘wind strategy’, and how to avoid the most costly mistakes, i.e. how to avoid the “train-wrecks”.
Here is the sleek F-TR Rig Bryan Litz used to win the 2015 F-TR Mid-Range and Long-Range Championships at Ben Avery:
Litz Ballistics Tips
Ballistics TIP ONE. If you’re having trouble getting your ballistic software to match actual drops, you need to look at a number of possible reasons. Here are some common issues that can cause problems.
Click Values Are Not Exact. Scopes and iron sights don’t always produce accurate adjustments. In other words, if your ballistics program predicts 30 MOA of drop, and you dial 30 MOA but hit low, it might be that your sight actually only moved 28 MOA (for example). To see if your sight is adjusting accurately, shoot a tall target at 100 yards and measure group separation when dialing your sight.
Barometric vs. Station Pressure. This is a commonly misunderstood input to ballistics programs. You can avoid this pitfall by remembering the following: station pressure is the actual measured pressure at your location, and you don’t need to tell the program your altitude when using station pressure. Barometric pressure is corrected for sea level. If you’re using barometric pressure, you also have to input your altitude.
Muzzle Velocity. Chronographs are not always as accurate as shooters think they are — your true MV may be off by 10-20 fps (or more). If your drop is different than predicted at long range, it might be because your muzzle velocity input is wrong.
Mixing Up BC (G1 vs. G7). Knowledgeable long range shooters know that the G7 standard is a more representative standard for modern LR bullets. However, using G7 BCs isn’t just a matter of clicking the ‘G7′ option in the program. The numeric value of the BC is different for G1 and G7. For example, the G1 BC of the Berger 155.5 grain Fullbore bullet is .464 but the G7 BC is .237. If you were to enter .464 but click on G7, the results would be way off.
Ballistics TIP TWO. A properly installed level is absolutely essential for long range shooting. Without a good level reference, your long range wind zero will be off due to minor canting of the rifle from side to side. You can verify that your level is installed correctly on a 100-yard ‘tall target’. Draw a plumb line straight up the target and verify that your groups track straight up this line as you go up in elevation.
Ballistics TIP THREE. If your long range ballistic predictions aren’t tracking, always come back and verify your 100-yard zero. Sometimes a simple zero shift can be misconstrued as errors in long range ballistics predictions.
Litz Competition Shooting Tips
Competition TIP ONE. Improving your scores in long range competition is a constant process of self-assessment. After each match, carefully analyze how you lost points and make a plan to improve. Beginning shooters will lose a lot of points to fundamental things like sight alignment and trigger control. Veteran shooters will lose far fewer points to a smaller list of mistakes. At every step along the way, always ask yourself why you’re losing points and address the issues. Sometimes the weak links that you need to work on aren’t your favorite thing to do, and success will take work in these areas as well.
Competition TIP TWO. Select your wind shooting strategy carefully. For beginners and veterans, most points are typically lost to wind. Successful shooters put a lot of thought into their approach to wind shooting. Sometimes it’s best to shoot fast and minimize the changes you’ll have to navigate. Other times it’s best to wait out a condition which may take several minutes. Develop a comfortable rest position so you have an easier time waiting when you should be waiting.
Competition TIP THREE. Actively avoid major train wrecks. Sounds obvious but it happens a lot. Select equipment that is reliable, get comfortable with it and have back-ups for important things. Don’t load on the verge of max pressure, don’t go to an important match with a barrel that’s near shot out, physically check tightness of all important screws prior to shooting each string. Observe what train wrecks you and others experience, and put measures in place to avoid them.
“Must-Watch” SWN Video has aerial view of Ben Avery plus highlights from Saturday
Photos by Steve Fiorenzo
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Get ready for a revolution in the F-Open, ELR, and Long-Range Benchrest games. Sierra just introduced a new 7mm bullet with a stunning 0.780 G1 BC. This new 197-grain HPBT MatchKing is one of the highest-BC, jacketed .284-caliber projectiles ever offered to the public. By comparison, Sierra’s own advanced 183-grain 7mm Matchking has a .707 G1 BC. That means the new 197-grainer has a 10% higher BC than the already slippery 183-grainer. That’s an impressive achievement by Sierra.
We expect top F-Open and long-range shooters will be trying the new 197-grainer as soon as they can get their hands on this new projectile. They may need new barrels however, as Sierra states: “This bullet requires a barrel twist rate of 1:7.5″ or faster”. Sierra expects to start shipping these slippery 7mm 197s very soon. You can order directly from Sierra’s website, stock code #1997, $54.20 for 100 bullets.
Factory Uniformed Bullet Tips
Sierra has officially announced that the 197gr SMK will come “pointed” from the factory. These impressive new 197s will have a “final meplat reducing operation” (pointing). This creates a higher BC (for less drag) and also makes the BC more uniform (reducing vertical spread at long range). Our tests of other factory-pointed Sierra MKs have demonstrated that Sierra does a very good job with this pointing operation. The “pointed” MatchKings we’ve shot recently had very nice tips, and did hold extremely “tight waterline” at 1000 yards, indicating that the pointing process does seem to enhance BC uniformity. Morever, radar-derived “real-world” BCs have been impressively uniform with the latest generation of pointed Sierra MKs (such as the new 110gr 6mm MatchKing).
Here is the statement from Sierra about the new bullets:
Shooters around the world will appreciate the accuracy and extreme long range performance of our new 7mm 197 grain HPBT (#1997). A sleek 27-caliber elongated ogive and a final meplat reducing operation (pointing) provide an increased ballistic coefficient for optimal wind resistance and velocity retention. To ensure precise bullet to bore alignment, a unique bearing surface to ogive junction uses the same 1.5 degree angle commonly found in many match rifle chamber throats.
While they are recognized around the world for record-setting accuracy, MatchKing® and Tipped MatchKing® bullets are not recommended for most hunting applications. Although MatchKing® and Tipped MatchKing® bullets are commonly used for varmint hunting, their design will not provide the same reliable explosive expansion at equivalent velocities in varmints compared to their lightly jacketed Hornet, Blitz BlitzKing, or Varminter counterparts.
New product tip from EdLongrange. We welcome reader submissions.
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Our friend Bill at Rifleshooter.com got his hands on some of Sierra’s brand new .30-Cal match bullets, the 195-grain Tipped Match Kings (TMKs). These feature an impressive 0.610 G1 BC above 2000 fps. We predict these new bullets will be popular with F-TR shooters shooting the .308 Winchester cartridge.
To see how the new 195gr TMKs perform, Bill loaded up some .308 Win ammo with IMR 4064, ranging from 40.5 grains up to 42.5 grains. That gave him a velocity range of 2438 FPS at the lowest charge weight, up to 2552 FPS at 42.5 grains. This was with a relatively short, 22-inch barrel. Best five-shot accuracy (and second lowest SD) was at 41.0 grains even, producing a 0.498 MOA five-shot group at 2480 fps (6.1 SD). CLICK HERE for full accuracy results.
I headed to the range on a brisk November day. Targets were 2″ orange dots at 100 yards. All shooting was done prone from a bipod with a rear bag. The Nightforce 3.5-15X scope was set at 15X. All ballistic information was recorded with a MagnetoSpeed barrel-mounted chronograph. Temperature was 54° F. Standard deviation for the loads ranged from 5.3 to 20.5 FPS. Average standard deviation was 12.5 FPS. Five-shot group sizes ranged from .521″ (.498 MOA, ) to 1.057″ (1.010 MOA). Average group size for all ten loads was .692″ (.661 MOA).
New 195gr TMK offers Impressive Long-Range Ballistics
Bill was also interested in how the ballistics of the new 195gr TMKs compared to other .30-cal projectiles. Even with a moderate, 2539 fps velocity, the new 195gr TMK showed less wind drift than other Sierras, thanks to its high 0.610 G1 BC. It also had a flatter trajectory beyond 600 yards than the 175gr and 190gr Sierra MatchKings. (The faster-flying 175gr TMK had slightly less drop at all yardages.)
Bill explains: “For comparison purposes, I selected the 42.0 grain load, with a muzzle velocity of 2,539 feet/second and an SD of 6.9. This load is compared to loads for the 190 SMK, 175 SMK, 175 TMK, and 168 Federal Gold Medal ammunition in the test rifle. In other words, these aren’t maximum loads, but loads that I have developed and would feel comfortable shooting a match with in the rifle shown (you may note the 190 SMK is fairly slow, but this is what the rifle liked). Also note that this rifle has a relatively short 22″ barrel compared to those you might find on a purpose built f-class rifle.”
Bill provides a full write-up on the Rifleshooter.com website complete with target photos and load details. If you are interested in these new 195-grainers, you should read the full report.
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You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.
One of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.
Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:
“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.
Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”
As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect.
It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet amsl), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.”
John Whidden of Whidden Gunworks used the .243 Winchester cartridge to win the 2016 NRA Long Range Championship, his fourth LR title at Camp Perry. John selected the .243 Win because it offers excellent ballistics with manageable recoil. John says that, at least for a sling shooter, the .243 Win is hard to beat at long range. Yes, John says, you can get somewhat better ballistics with a .284 Win or .300 WSM, but you’ll pay a heavy price in increased recoil.
.243 Winchester — The Forgotten 6mm Cartridge for Long Range
by John Whidden, 2016 National Long Range Champion
My experience with the .243 cartridge for use as a Long Range High Power cartridge dates back about 10 years or so. After building a .300 WSM, I realized that the recoil was hurting the quality of my shots. The WSM shot great, but I couldn’t always execute good shots when shooting it. From here I built a 6.5-284, and it shot well. I also had a very accurate 6mmBR at the time, and my logic in going to the .243 Win was to get wind performance equal to the 6.5-284 with recoil similar to the 6mmBR. The experiment has worked out well indeed!
Championship-Winning Load: Berger Bullets, Lapua Brass, and Vihtavuori N160
For a load, currently I’m shooting Lapua brass, PMC primers (Russian, similar to Wolf), VihtaVuori N160 single-base powder, and Berger 105 grain Hybrid bullets. I switched to the Hybrid bullets fairly recently at the beginning of the 2015 season. Previously I shot the 105gr Berger hunting VLDs, and in testing I found that the Hybrids were just as accurate without having to seat the bullet into the lands. The velocity of this combination when shot through the excellent Bartlein 5R barrels (32” length) is around 3275 FPS.
For my match ammo, I seat the Berger 105 Hybrids well off the lands — my bullets are “jumping” from .035″-.060″. I only use one seating depth for ammunition for multiple guns (I know some benchrest shooters will stop reading right here!) and the bullets jump further in the worn barrels than in the fresh barrels. The bullets are pointed up in our Bullet Pointing Die System and are moly-coated. The moly (molybdenum disulfide) does extend the cleaning interval a little bit, probably 20% or so. The Lapua .243 Win brass is all neck-turned to .0125″ thickness.
Whidden’s .243 Win Ammo is Loaded on a Dillon
My loading process is different than many people expect. I load my ammo on a Dillon 650 progressive press using our own Whidden Gunworks dies. However powder charges are individually weighed with a stand-alone automated scale/trickler system from AutoTrickler.com (see below). Employing a high-end force restoration scale, this micro-processor controlled system offers single-kernel precision. The weighed charges are then dropped into the cases with a funnel mounted to the Dillon head.
The Lapua .243 Win brass is full-length sized every time, and I run one of our custom-sized expanders in my sizer die. The expander measures .243″ which yields the desired .001″ neck tension. In my experience, the best way to get consistent neck tension is to run an expander in the case neck at some point. When sizing the case neck by a minimal amount such as is the case here, I don’t find any negative points in using an expander in the sizer die.
In my experience, the keys to accurate long range ammo are top quality bullets and the most consistent neck tension you can produce. From these starting points, the use of quality components and accurate powder measurement will finish out the magic.
Great Ballistics with 6mm 105s at 3275 FPS
Running at an impressive 3275 FPS, Berger 6mm 105 grain Hybrids deliver ballistics that are hard to beat, according to John Whidden:
“My .243 Win shoots inside a 6.5-284 with 142-grainers. Nothing out there is really ahead of [the .243], in 1000-yard ballistics unless you get into the short magnums or .284s and those carry a very significant recoil penalty. In the past I did shoot the 6.5-284. I went to the .243 Win because it had similar ballistics but had much less recoil. It doesn’t beat me up as much and is not as fatiguing.
With the .243 Win, there’s no tensing-up, no anticipating. With the reduced recoil (compared to a 7mm or big .308), I can break and shoot very good quality shots. I find I just shoot better shots with the .243 than I ever did with the 6.5-284.”
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At the request of our readers, we provide select “Deals of the Week”. Every Monday morning we offer our Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
1. Kelbly.com — 15% Off Discount on All Products
Looking for a Panda or Atlas Action, or a complete match rifle? Here’s a great promotion from our friends at Kelbly’s. Now through Tuesday, August 23, 2016 you can get 15% of ANYthing on the Kelblys.com website. That includes rifles, actions, stocks, barrels, scope rings, muzzle brakes, Berger bullets, accessories and more. To save big, use code 15ALL at checkout. Don’t delay — this offer expires at 11:59 pm on September 1, 2016.
2. EuroOptic.com — Tikka T3 Liquidation Sale, Huge Discounts
Looking for a great price on an excellent hunting rifle? Here is the Tikka Deal of the Decade. EuroOptic.com has received nearly 3,500 Tikka T3 rifles, which will be sold at deep discounts as part of an inventory clearance program by Beretta, Tikka’s parent company. The Tikka T3 is a good, stout rifle with a smooth, 3-lug action, crisp trigger, and quality barrel. Accuracy is typically well under 1 MOA (for three shots). T3 barreled actions also are a good “core” for a tactical build. The strong T3 action handles detachable magazines, and fits a variety of third-party stocks.
3. Monmouth — Hornady 6.5 Creedmoor Brass, $34.95 for 50
The 6.5 Creedmoor has become one of the most popular chamberings for tactical/practical shooting. This mid-sized cartridge offers excellent ballistic performance with 120-140gr bullets, with moderate recoil and excellent inherent accuracy. Now you can get Hornady-brand 6.5 Creedmoor brass at a very good price: $34.95 for 50 cases (that’s $69.90 per 100).
If you are looking for a rugged, reliable, and affordable spotting scope to watch flags, mirage, and shot spotting discs, this angled-body Kowa TSN-61 will do the job. And $259.00 with free, fast Prime Shipping is a great deal. These Kowa spotters have been used successfully for years by prone and High Power competitors. Sure the glass can’t rival the latest top-of-the-line HD spotting scopes, but the TSN-61 is a small fraction of the price of high-end models which cost $2000 or more. The money you save can buy four premium hand-lapped barrels. NOTE: Eyepieces are sold separately — expect to pay $275.00 – $300.00 for a Kowa 20-60X Zoom eyepiece.
5. Midsouth — $15.00 HazMat Fee with 15-lb Powder Purchase
When you purchase powder, it makes sense to buy in bulk. That way you get powder from the same lot, and save on the HazMat fees. Now you have even more incentive to place a big order. Right now Midsouth is offering $15.00 Hazmat with orders of 15 or more pounds of powder. Get 15 one-pounders or two eight-pound jugs and you’ll qualify. Midsouth has a large selection of popular powders in stock, including Hodgdon Varget, H4198, H48931sc, and the new IMR Enduron powders. With this special HazMat deal you can save up to $20.00 (many vendors charge $35.00 HazMat per order). Don’t hesitate — this offer ends 8/25/2016.
6. Amazon — Tipton Gun Vise, $30.32 (free Prime Shipping)
This is an awesome deal on a durable, well-designed polymer Gun Vise that every rifle owner can use. Your Editor has one of these units which has served well for more than a decade. The base has compartments for solvents, patches, and tools. The cradles and pads contacting your gunstock are a soft, rubber-like material that is gentle on fine finishes. This vise is relatively light in weight, but sturdy enough to support big, heavy rifles.
A Mildot Master is one item every tactical/practical shooter should own. This handy tool has been used successfully for years. It doesn’t require batteries, no keypad data entry is require through a keypad is necessary, as the device is purely analog. No complex calculations for determination of telescopic sight adjustment or hold-over at various ranges are necessary, as the scales of the device convert drop/drift figures directly into both MOA and mils.
8. Amazon — Ten-Pack of 2″-Diameter Splatter Targets, $8.99
We use these splatter targets for fun shoots and practice at 300 and 400 yards. When hit, each shot displays as a bright, neon-green/yellow circle. That makes it easy to spot your shots, even with relatively low-power optics. These targets also work great for handgun practice at shorter distances. For just $8.99 you get ten sheets each with 16 stick-on circles — a total of 160 target bulls.
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Here’s a significant new addition to our knowledge base for Long-Range shooting. Hornady has released a new Ballistics Calculator that employs bullet profiles derived from Doppler radar testing and 3D projectile modeling. Hornady’s Patent Pending 4DOF™ Ballistic Calculator provides trajectory solutions based on projectile Drag Coefficient (not static G1/G7 ballistic coefficients) along with the exact physical modeling of projectiles and their mass and aerodynamic properties. This new 4DOF (Four Degrees of Freedom) calculator also accounts for spin drift and the subtle VERTICAL effects of crosswinds.
We strongly recommend you watch this video from start to finish. In greater detail than is possible here, this video explains how the 4DOF System works, and why it is more sophisticated than other commercially-offered Ballistics calculators. There’s a LOT going on here…
Aerodynamic Jump from Crosswind Calculated
According to Hornady, the 4DOF Ballistics Calculator “is the first publicly-available program that will correctly calculate the vertical shift a bullet experiences as it encounters a crosswind.” This effect is called aerodynamic jump. The use of radar-derived drag profiles, correct projectile dynamics, aerodynamic jump, and spin drift enable the Hornady® 4DOF™ ballistic calculator to provide very sophisticated solutions. Hornady says its 4DOF solver is “the most accurate commercially available trajectory program … even at extreme ranges.”
“Current ballistic calculators provide three degrees of freedom in their approach — windage, elevation, and range — but treat the projectile as an inanimate lump flying through the air,” said Dave Emary, Hornady Chief Ballistician. “This program incorporates the projectile’s movement in the standard three degrees but also adds its movement about its center of gravity and subsequent angle relative to its line of flight, which is the fourth degree of freedom.”
Using Doppler radar, Hornady engineers have calculated exact drag versus velocity curves for each bullet in the 4DOF™ calculator library. This means the 4DOF™ calculator should provicde more precise long range solutions than calulators that rely on simple BC numbers or drag curves based with limited data collection points. Emary adds: “The Hornady 4DOF also accurately calculates angled shots by accounting for important conditions that [other ballistic] programs overlook.”
“This calculator doesn’t utilize BCs (Ballistic Coefficients) like other calculators,” added Jayden Quinlan, Hornady Ballistics Engineer. “Why compare the flight of your bullet to a standard G1 or G7 projectile when you can use your own projectile as the standard?” That makes sense, but users must remember that Hornady’s 4DOF projectile “library” includes mostly Hornady-made bullets. However, in addition to Hornady bullets, the 4DOF Calculator currently does list seven Berger projectiles, six Sierra projectiles, and one Lapua bullet type. For example, Sierra’s new 183gr 7mm MatchKing is listed, as is Berger’s 105gr 6mm Hybrid.
This Video Explains How to Use Hornady’s New 4DOF Ballistics Calculator
Using the 4DOF™ Ballistic Calculator:
The Hornady 4DOF Ballistic Calculator provides trajectory solutions based on projectile Drag Coefficient (not ballistic coefficients) along with exact physical modeling of the projectile and its mass and aerodynamic properties. Additionally, it calculates the vertical shift a bullet experiences as it encounters a crosswind, i.e. “aerodynamic jump”. The use of drag coefficients, projectile dynamics, aerodynamic jump, and spin drift enable the 4DOF Ballistic Calculator to accurately measure trajectories even at extreme ranges. It is ideal for both long range and moderate distances and is available for the low-drag precision bullets listed in the drop down menu of the calculator. For calculating trajectories of traditional hunting and varmint bullets using BCs (ballistic coefficients), you can use Hornady’s Standard Ballistics Calculator.
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In this video, Bryan Litz of Applied Ballistics talks about Density Altitude and the effect of atmospheric conditions on bullet flight. Bryan explains why you must accurately account for Density Altitude when figuring long-range trajectories.
Bryan tells us: “One of the important elements in calculating a fire solution for long-range shooting is understanding the effect of atmospherics. Temperature, pressure, and humidity all affect the air density that the bullet’s flying through. You can combine all those effects into one number (value) called ‘Density Altitude’. That means that you just have one number to track instead of three. But, ultimately, what you are doing is that you are describing to your ballistics solver the characteristics of the atmosphere that your bullet’s flying through so that the software can make the necessary adjustments and account for it in its calculations for drop and wind drift.”
Bryan adds: “Once you get past 500 or 600 yards you really need to start paying careful attention to atmospherics and account for them in your ballistic solutions”. You can learn more about Density Altitude in Bryan’s book, Applied Ballistics for Long Range Shooting (Third Edition).
General Scientific Definition of Density Altitude
Density altitude is the altitude relative to the standard atmosphere conditions (ISA) at which the air density would be equal to the indicated air density at the place of observation. Density altitude can be calculated from atmospheric pressure and temperature (assuming dry air). Here is the formula:
Air is more dense at lower elevations primarily because of gravity: “As gravity pulls the air towards the ground, [lower] molecules are subject to the additional weight of all the molecules above. This additional weight means the air pressure is highest at sea level, and diminishes with increases in elevation”.*
Both an increase in temperature, decrease in atmospheric pressure, and, to a much lesser degree, increase in humidity will cause an increase in density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.
In this NSSF Video, Ryan Cleckner, a former Sniper Instructor for the 1st Ranger Battalion, explains how to gather and organize D.O.P.E. (Data On Previous Engagements) and how to organize this information to make it readily available in the field. As the term is used by Cleckner, D.O.P.E. includes observed bullet drop information at various distances, as well as the effects of wind, temperature changes, humidity and other environmental variables.
If you know your muzzle velocity, and bullet BC, a modern Ballistics App should be able to calculate bullet drop with great precision at distances from 100-1000 yards — often within a couple 1/4-MOA clicks. However, because a bullet’s BC is actually dynamic (changing with speed), and because ballistics solvers can’t perfectly account for all variables, it’s useful to collect actual, verified bullet drop data.
It’s smart to start with ballistics data from a solver app, but, as Cleckner explains: “Odds are, you’re going to have to fine-tune that data to your gun and your system. Every scope and every rifle and every bullet [type] act differently. Your scope may not track the same from rifle to rifle, so it’s important you get the data that’s unique to you.” Cleckner also explains that the ballistic data supplied with some factory ammo may only give you a crude approximation of how that ammo will actually shoot through your gun.
Keeping Your Drop Data with the Rifle
Cleckner also offers some good advice on how to record D.O.P.E. on simple index cards, and how to keep your ballistics data with your rifle. This can be done with a laminated drop chart or data transferred to a scope cover (photo right). CLICK HERE, to learn more about creating handy field data cards.
At the 4:15 mark on the video, Cleckner shows a calibrated tape he has fitted around the turret of his riflescope. The tape shows distance numbers (e.g. “4” for 400 yards, “5” for 500 yards etc.) that correspond with the number of clicks (rotation) required to be zeroed at that particular distance. With that system, you simply “dial your distance” and your point of impact should equal your point of aim. It takes some skill (and the right software) to create these tapes, but the concept is great.
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The USAMU recently published a “how-to” article about bullet sorting. While many of us may sort bullets by base-to-ogive length (and/or weight), the USAMU story explores the “how and why” of sorting bullets by Overall Length (OAL). Read the article highlights below, and make your own decision as to whether OAL sorting is worth the time and effort. Bryan Litz of Applied Ballistics says that sorting by OAL is not a bad idea, but base-to-ogive bullet sorting probably represents a better investment of your time.
Bullet Sorting by Overall Length
We’d like to share a specialized handloading technique which we’ve long found beneficial to our long-range (600 yards and beyond) accuracy. Sorting of bullets for extreme long range (LR) accuracy is not difficult to do, but some background in theory is needed.
Here at USAMU’s Handloading Shop, we only sort individual bullets for the most demanding Long-Range applications and important competitions. Only the most accurate rifles and shooters can fully exploit the benefits of this technique. The basic sorting process involves measuring the Overall Length (OAL) of the bullets, and grouping them in 0.001″ increments. It’s not unusual to find lots of match bullets that vary as much as 0.015″-0.020″ in length throughout the lot, although lots with much less variation are seen as well. Even in bullet lots with 0.015″ OAL variation, the bullet base-to-ogive length will show much less variation. Hence, our basic sort is by bullet OAL. One obvious benefit of sorting is easily seen in the attached photo. The few bullets that are VERY different from the average are culled out, reducing probable fliers.
How does one know what OAL increments to use when sorting? The answer is simple. As each lot of bullets is unique in its OAL distribution, it’s best to sample your bullet lot and see how they are distributed. In the attached photo, you will see a set of loading trays with a strip of masking tape running along the bottom. Each vertical row of holes is numbered in 0.001″ increments corresponding to the bullets’ OAL. A digital caliper makes this task much easier. As each bullet is measured, it is placed in the line of holes for its’ OAL, and gradually, a roughly bell-shaped curve begins to form.
Note that near the center, bullets are much more plentiful than near the edges. At the extreme edges, there are a few that differ markedly from the average, and these make great chronograph or sighting-in fodder. We recommend using a sample of 200 bullets from your lot, and 300 is even better. Some bullet lots are very consistent, with a tall, narrow band of highly-uniform bullets clustered together over just a few thousandths spread. Other lots will show a long, relatively flat curve (less uniform), and you may also see curves with 2 or more “spikes” separated by several 0.001″ OAL increments.
Bullet Sorting (OAL vs. Base-to-Ogive vs. Weight) — Litz Talks
I’m often asked what is a the best measure to sort bullets by, and the answer (to this and many other questions in ballistics) is: it depends.
Choosing to sort by overall length (OAL), base to ogive (BTO), bearing surface, weight, etc. can get overwhelming. Shooters typically look for something they can measure, which shows a variation and sort by that. It’s common for dimensional variations to correlate. For example, bullets which are longer in OAL are typically also shorter in BTO, and have longer noses. All these are symptoms of a bullet that was pushed a little further into the pointing die, or possibly had more than average lube while being swaged. So in essence, if you sort by BTO, you’re measuring one symptom which can indicate a pattern in the bullets shape.
So, the question still stands — what should you measure? You’ll always see more variation in OAL than BTO, so it’s easier to sort by OAL. But sometimes the bullet tips can be jagged and have small burrs which can be misleading. Measuring BTO will result in a lower spread, but is a more direct measure of bullet uniformity.
Then there’s the question of; how much variation is too much, or, how many bins should you sort into? Shooters who see 0.025” variation in BTO may choose to sort into 5 bins of 0.005”. But if you have only 0.005” variation in the box, you’ll still sort into 5 bins of 0.001”. What’s correct? You have to shoot to know. Live fire testing will answer more questions, and answer them more decisively than any amount of discussion on the subject. The test I recommend is to identify bullets on the extreme short end of the spectrum, and some on the extreme long end. Load at least 10 rounds of each, and take turns shooting 5-shot groups with them. If there is a difference, it will be evident. The results of the testing will answer your question of: should I sort based on X, Y, or Z?”
You can read more discussion on this and other similar subjects in the new Ballistics & Bullets board in the Accurateshooter.com forum. Heres a link to the thread which is discussing bullet sorting: Bullet Sorting Thread
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In our Shooters’ Forum, there was an discussion about a range that was threatened with closure because rifle over-shoots were hitting a farm building over two miles from the firing line. One reader was skeptical of this, asking “how’s that possible — were these guys aiming at the stars?” Actually, you may be surprised. It doesn’t take much up-angle on a rifle to have a bullet land miles down-range. That’s why it’s so important that hunters and target shooters always orient their barrels in a safe direction (and angle). Shooters may not realize how much a small tilt of the barrel (above horizontal) can alter a bullet’s trajectory.
How many degrees of muzzle elevation do you think it would take to hit a barn at 3000 yards? Ten Degrees? Twenty Degrees? Actually the answer is much less — for a typical hunting cartridge, five to seven degrees of up-angle on the rifle is enough to create a trajectory that will have your bullet impacting at 3000 yards — that’s 1.7 miles away!
Five degrees isn’t much at all. Look at the diagram above. The angle actually displayed for the up-tilted rifle is a true 5.07 degrees (above horizontal). Using JBM Ballistics, we calculated 5.07° as the angle that would produce a 3000-yard impact with a 185gr .30-caliber bullet launched at 2850 fps MV. That would be a moderate “book load” for a .300 Win Mag deer rifle.
Here’s how we derived the angle value. Using Litz-derived BCs for a 185gr Berger Hunting VLD launched at 2850 fps, the drop at 3000 yards is 304.1 MOA (Minutes of Angle), assuming a 100-yard zero. This was calculated using a G7 BC with the JBM Ballistics Program. There are 60 MOA for each 1 degree of Angle. Thus, 304.1 MOA equals 5.068 degrees. So, that means that if you tilt up your muzzle just slightly over five degrees, your 185gr bullet (2850 fps MV) will impact 3000 yards down-range.
Figuring Trajectories with Different Bullets and MVs
If the bullet travels slower, or if you shoot a bullet with a lower BC, the angle elevation required for a 3000-yard impact goes up, but the principle is the same. Let’s say you have a 168gr HPBT MatchKing launched at 2750 fps MV from a .308 Winchester. (That’s a typical tactical load.) With a 100-yard zero, the total drop is 440.1 MOA, or 7.335 degrees. That’s more up-tilt than our example above, but seven degrees is still not that much, when you consider how a rifle might be handled during a negligent discharge. Think about a hunter getting into position for a prone shot. If careless, he could easily touch off the trigger with a muzzle up-angle of 10 degrees or more. Even when shooting from the bench, there is the possibility of discharging a rifle before the gun is leveled, sending the shot over the berm and, potentially, thousands of yards down-range.
Hopefully this article has shown folks that a very small amount of barrel elevation can make a huge difference in your bullet’s trajectory, and where it eventually lands. Nobody wants to put holes in a distant neighbor’s house, or worse yet, have the shot cause injury. Let’s go back to our original example of a 185gr bullet with a MV of 2850 fps. According to JBM, this projectile will still be traveling 687 fps at 3000 yards, with 193.7 ft/lbs of retained energy at that distance. That’s more than enough energy to be deadly.
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“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag….
Ruprecht Nennstiel, a forensic ballistics expert from Wiesbaden, Germany, has authored a great resource about bullet behavior in flight. Nennstiel’s comprehensive article, How Do Bullets Fly, explains all the forces which affect bullet flight including gravity, wind, gyroscopic effects, aerodynamic drag, and lift. Nennstiel even explains the rather arcane Magnus Force and Coriolis Effect which come into play at long ranges. Nennstiel’s remarkable resource contains many useful illustrations plus new experimental observations of bullets fired from small arms, both at short and at long ranges.
Shadowgraph of .308 Winchester Bullet
A convenient index is provided so you can study each particular force in sequence. Writing with clear, precise prose, Nennstiel explains each key factor that affects external ballistics. For starters, we all know that bullets spin when launched from a rifled barrel. But Nennstiel explains in greater detail how this spinning creates gyroscopic stability:
“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag, the plane, formed by the velocity vector ‘v’ and the longitudinal axis of the bullet. In the absence of spin, the yaw angle ‘δ’ would grow and the bullet would tumble.
If the bullet has sufficient spin, saying if it rotates fast enough about its axis of form, the gyroscopic effect takes place: the bullet’s longitudinal axis moves into the direction of the overturning moment, perpendicular to the plane of drag. This axis shift however alters the plane of drag, which then rotates about the velocity vector. This movement is called precession or slow mode oscillation.”
Raise Your Ballistic IQ
Though comprehensible to the average reader with some grounding in basic physics, Nennstiel’s work is really the equivalent of a Ph.D thesis in external ballistics. You could easily spend hours reading (and re-reading) all the primary material as well as the detailed FAQ section. But we think it’s worth plowing into How Do Bullets Fly from start to finish. We suggest you bookmark the page for future reference. You can also download the complete article for future reference and offline reading.
The biggest Berger bullet ever is on its way. In early summer, Berger Bullets will unveil its first-ever .50-Caliber projectile and its first-ever solid. This new 750gr bullet, called the TItan (for Titanium), features heat-resistant CNC-machined Titanium bullet tips with threaded shafts. TItan bullet bodies are precisely tapped (with a fine pitch) to accept the threaded tips. This allows for ultra-precise tip alignment and perfect concentricity. Another benefit of this threaded attachment system is that hand-loaders can change out tips, selecting a particular tip profile for different applications. Initially three tip types will be offered: Hunting (for increased expansion), Match (for maximum BC), and Tactical (for military/LEO applications). The Match Tip gives the new TItan a spectacular 1.25 G1 BC.
The field-tested G7 BC is still “top-secret” but Bryan Litz reports: “The number we’ve seen with the prototype TItans is a game-changer… nothing will touch it.” How impressive is the new TItan? Bryan told us: “Look, I don’t want to let the cat out of the bag, but I’m building a new .50 just to shoot this thing, and we’re looking to go sub-MOA at 2500 yards.”
The Titanium bullet tips set the new Berger TItan apart from all other projectiles on the market. Berger Ballistician Bryan Litz noted: “We wanted the ability to adapt bullet performance to particular applications. With interchangeable bullet tips you can increase BC or increase terminal performance. In addition, with the Titanium material, we have the most heat-resistant bullet tips in the business. Compare the heat resistance of Titanium with any thing else — red, green, or otherwise.” Recently, Hornady rolled out a line of ELD™ match bullets with heat-resistant red plastic tips. Berger’s Titanium tips can withstand much higher temperatures than ANY polymer tips. “Our Titanium tips are essentially heat-proof. The amount of heat required to compromise the tips would melt your barrel first”, said a Berger production engineer.
Berger Bullets President Eric Stecker said the company considered other monikers for its super-sized .50 Caliber projectile before finalizing on the name “TItan”: “For the new .50 we needed something to top the ‘Juggernaut’ name we use for our big 30s. We thought about ‘Super-Solid’ and even considered calling the big .50 the ‘Berger King Whopper’, but that didn’t work for obvious reasons. We finally settled on ‘TItan’ because it means ‘big’ and has the Titanium connection, and we can trademark that. But Bryan and some of the production guys in the shop still call this big .50 the ‘Whopper'”.
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After the success of its recent winter Ballistics seminar in Michigan, Applied Ballistics has decided to take its show on the road, offering additional Ballistics seminars in three different states (Texas, Michigan, and North Carolina). These three seminars will cover a wide range of topics, with the primary focus on basic to advanced ballistics principles as applied to long-range shooting. Registration is now open for the three (3) upcoming Ballistics Seminars:
This video explains the subjects covered by Applied Ballistics Seminars:
Ballistician (and current F-TR National Mid-Range and Long-Range Champion) Bryan Litz will be the primary speaker at the spring, summer, and fall seminars. He will present material from his books and the Applied Ballistics Lab, and he will discuss his experience shooting in various disciplines. The seminar will feature structured presentations by Bryan and other noted speakers, but a great deal of time will be alloted for questions and discussion. By the end of the seminar, participants should have a much better understanding of how to apply ballistics in the real world to hit long-range targets. Along with Bryan, other respected experts will include:
Emil Praslick III – Head coach of the U.S. Palma team and retired head coach of the U.S. Army Marksmanship Unit. Emil will discuss tactics, strategy, and mindset for successful wind-reading.
Eric Stecker – Master Bulletsmith and President of Berger Bullets. Eric will be presenting on precision bullet making technology.
Nick Vitalbo – Owner of nVisti Tactical Innovations and chief engineer for Applied Ballistics. Nick will discuss the state of the art in laser rangefinders and wind reading devices.
Mitch Fitzpatrick – Applied Ballistics intern and owner of Lethal Precision Arms. Mitch specializes in Extended Long Range (ELR) cartridge selection and rifle design.
Ballistic Solvers – How they work, best practices, demos.
Weapon Employment Zone (WEZ) Analysis – How to determine and improve hit percentage.
Optics and Laser Technology – State of the Art.
The seminars costs $500.00. But consider this — each seminar participant will receive the entire library of Applied Ballistics books and DVDs, valued at $234.75, PLUS a free copy of Applied Ballistics Analytics software, valued at $200.00. So you will be getting nearly $435.00 worth of books, DVDs, and software. In addition, a DVD of the seminar will be mailed to each attendee after the seminar concludes.
On LongRangeHunting.com, you’ll find a good article by Shawn Carlock about wind reading. Shawn is a veteran law enforcement marksman and a past USPSA national precision rifle champion. Shawn offers good advice on how to estimate wind speeds and directions using a multitude of available indicators — not just your wind gauge: “Use anything at your disposal to accurately estimate the wind’s velocity. I keep and use a Kestrel for reading conditions….The Kestrel is very accurate but will only tell you what the conditions are where you are standing. I practice by looking at grass, brush, trees, dust, wind flags, mirage, rain, fog and anything else that will give me info on velocity and then estimate the speed.”
Shawn also explains how terrain features can cause vertical wind effects. A hunter on a hilltop must account for bullet rise if there is a headwind blowing up the slope. Many shooters consider wind in only one plane — the horizontal. In fact wind has vertical components, both up and down. If you have piloted a small aircraft you know how important vertical wind vectors can be. Match shooters will also experience vertical rise when there is a strong tailwind blowing over an up-sloping berm ahead of the target emplacements. Overall, Shawn concludes: “The more time you spend studying the wind and its effect over varying terrain the more successful you will be as a long-range shooter and hunter.”
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Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. This past week’s “Handloading Hump Day” article, the latest in a 7-part series, relates to chronograph testing and statistical samples. We highly recommend you read this article, which offers some important tips that can benefit any hand-loader. Visit the USAMU Facebook page next Wednesday for the next installment.
Chronograph Testing — Set-Up, Sample Sizes, and Velocity Factors
Initial Chronograph Setup
A chronograph is an instrument designed to measure bullet velocity. Typically, the bullet casts a shadow as it passes over two electronic sensors placed a given distance apart. The first screen is the “start” screen, and it triggers an internal, high-speed counter. As the bullet passes the second, or “stop” screen, the counter is stopped. Then, appropriate math of time vs. distance traveled reveals the bullet’s velocity. Most home chronographs use either 2- or 4-foot spacing between sensors. Longer spacing can add some accuracy to the system, but with high-quality chronographs, 4-foot spacing is certainly adequate.
Laboratory chronographs usually have six feet or more between sensors. Depending upon the make and model of ones chronograph, it should come with instructions on how far the “start” screen should be placed from one’s muzzle. Other details include adequate light (indoors or outdoors), light diffusers over the sensors as needed, and protecting the start screen from blast and debris such as shotgun wads, etc. When assembling a sky-screen system, the spacing between sensors must be extremely accurate to allow correct velocity readings.
Statistics: Group Sizes, Distances and Sample Sizes
How many groups should we fire, and how many shots per group? These questions are matters of judgment, to a degree. First, to best assess how ones ammunition will perform in competition, it should be test-fired at the actual distance for which it will be used. [That means] 600-yard or 1000-yard ammo should be tested at 600 and 1000 yards, respectively, if possible. It is possible to work up very accurate ammunition at 100 or 200 yards that does not perform well as ranges increase. Sometimes, a change in powder type can correct this and produce a load that really shines at longer range.
The number of shots fired per group should be realistic for the course of fire. That is, if one will be firing 10-shot strings in competition then final accuracy testing, at least, should involve 10-shot strings. These will reflect the rifles’ true capability. Knowing this will help the shooter better decide in competition whether a shot requires a sight adjustment, or if it merely struck within the normal accuracy radius of his rifle.
How many groups are needed for a valid test? Here, much depends on the precision with which one can gather the accuracy data. If shooting from a machine rest in good weather conditions, two or three 10-shot groups at full distance may be very adequate. If it’s windy, the rifle or ammunition are marginal, or the shooter is not confident in his ability to consistently fire every shot accurately, then a few more groups may give a better picture of the rifle’s true average.
Preliminary Load Development and Velocities
When developing a load for ones firearm, a chronograph is a very useful tool. Naturally, it tells the bullet speed, allowing ballistic calculations for wind deflection and trajectory, as well as velocity variation. It can also be used, in conjunction with recent handloading manuals, as an indirect indicator of pressure.
Differences between individual barrels, chamber throats, and powder lots, plus many other variables, can cause results to differ from those cited in the manuals. Thus, beware the notion of a “magical high-speed barrel.”
When Velocities Raise Pressure Concerns — Suppose the manual states that their 26-inch .260 barrel achieved 2900 fps with X bullet, Y powder, Z case, and W primer. If you achieve that speed with identical components in your 26-inch barrel while using five (5) grains less powder, that should raise a red flag. Pressures may be at or near maximum in your rifle, despite the higher “maximum” charge cited in the manual. Observe for pressure indicators as discussed in your manuals, and never exceed published maximum powder charges.
When working up a potential match load for your rifle, it is wise to survey at least 2-3 current factory sources of data for your powder/bullet combination. This will give you a sense of the variations possible due to random factors. Then, beginning at a safe, listed “starting” powder charge, work your way up in increasing powder increments while shooting over the chronograph. Also, assess your brass and rifle for signs of increasing pressure.
What size powder increments should be used? This depends on the case volume and powder chosen. A 0.3 grain or 0.5 grain increase in powder charge may be significant in a .223, but of little consequence in a .300 Magnum. Faster burning powders are more sensitive to small changes in powder charge, increasing pressures more rapidly than slow-burning powders.
Chronograph Sample Sizes — Factors to Consider
How many shots should one fire to obtain an accurate velocity for each powder charge increment when loading? That depends in part on the uniformity of velocities given by your particular powder/bullet/barrel combination.
For example: a 3- or 5-shot sample gives an extreme spread (ES) of 140 fps between the high and low velocities recorded. The lack of uniformity indicates that firing 1 or 2 shots over the chronograph to check a powder charge is likely to give a wide margin of error. In such a case, larger sample sizes will give a better idea of the true, average velocity. While approaching the loading manual’s listed maximum charge, track the ascending velocities per charge increment. One may well see that as charges approach maximum, velocities may become much more uniform. Moreover, velocity gains per increment of increase often become smaller. Ideally, one won’t encounter velocity variations this large. Changing primers and/or neck tension may increase uniformity. If wide variations persist, however, a different powder may offer great improvement.
Consider this: A 2-shot scan gives double the data of a one-shot sample. A 4-shot sample gives twice the data of a 2-shot scan. Larger samples are particularly useful if there is much velocity variation in the population.
On the other hand, one might already be familiar with a particular powder/bullet combination in one’s barrel. If it is known to have little variation, a 1 or 2-shot scan in the early stages while working up toward the maximum can be useful, while saving expensive bullets. As powder charges approach their maximum, some like to test accuracy while shooting over the chronograph. Although it’s a bit trickier to set up the bench, chronograph and target, this does yield more data per bullets expended. In such an instance, 5-shot or even 10-shot groups may be desirable at times.
Consider 20-Shot Sample for Long-Range Match Loads
Once one arrives at a load combination intended for competition use, one should chronograph at least a 10-shot sample. This gives a reasonable picture both of the load’s uniformity and its average velocity. For long range use, a 20-shot sample of ones finalized match load is even better. This accurately shows the uniformity of one’s velocities over time. It is more likely to reveal any rare shots that develop velocities significantly different from the average.
Thus ends Part 7 in our series on Accuracy Testing and Chronographing. Next week, we’ll conclude our section on Chronograph Testing. Until then, stay safe and enjoy the shooting sports!
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The Coriolis Effect comes into play with extreme long-range shots like this. The rotation of the earth actually moves the target a small distance (in space) during the course of the bullet’s flight. Photo by Dustin Ellermann at Whittington Center Range.
When 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 has produced a short video that explains the Coriolis Effect. 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 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)
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Bryan Litz with his F-TR Nat’l Championship-winnning rifle, and the man who built it, John Pierce.
Bryan Litz knows something about bullet shapes and dimensions. He’s the chief designer of many of Berger’s projectiles, including the successful line of Hybrid bullets. Bryan also understands how bullets actually perform in “real world” competition. Bryan won BOTH the Mid-Range and Long-Range National F-TR Championships this year, a remarkable accomplishment. With Bryan’s technical expertise combined with his shooting skills, few people are better qualified to answer the question: “how should I sort bullets when loading for competition?”
Bullet Sorting Strategies — OAL vs. Base to Ogive
At the 2015 Berger Southwest Nationals, Forum member Erik Cortina cornered Bryan Litz of Applied Ballistics. Erik was curious about bullet sorting. Knowing that bullets can be sorted by many different criteria (e.g. weight, overall length, base to ogive length, actual bearing surface length etc.) Erik asked Bryan to specify the most important dimension to consider when sorting. Bryan recommended sorting by “Base to Ogive”. Litz noted that: “Sorting by overall length can be misleading because of the nature of the open-tip match bullet. You might get a bullet that measures longer because it has a jagged [tip], but that bullet might not fly any different. But measuring base to ogive might indicate that the bullet is formed differently — basically it’s a higher resolution measurement….”
Here’s a valuable web resource our readers should bookmark for easy access in the future. ShootForum.com offers a vast Bullet Database, which includes roughly 3900 bullet designs in all. We counted nearly 200 different 6mm bullets! The bullet info comes from the makers of QuickLOAD Software. Access to the online database is FREE. Most database entries include Caliber, Manufacturer, Stated Bullet Weight, True Bullet Weight, Length, Sectional Density (SD), and Ballistic Coefficient.* In many cases multiple BCs are provided for different velocity ranges.
The database is great if you’re looking for an unusual caliber, or you want a non-standard bullet diameter to fit a barrel that is tighter or looser than spec. You’ll find the popular jacketed bullets from major makers, plus solids, plated bullets, and even cast bullets. For those who don’t already own QuickLOAD software, this is a great resource, providing access to a wealth of bullet information.
Values for Changed Bullet Designs
Some of our readers have noted some variances with BCs and OALs with recently changed bullet designs. In general the database is very useful and accurate. However, as with any data resource this extensive, there will be a few items that need to be updated. Manufacturers can and do modify bullet shapes. Kevin Adams, one of the creators of the database, explains: “Thanks for mentioning this database. It took us a long time to collate this information and have agreement to publish it. Please keep in mind that individual batches of bullets will differ from the manufacturers’ stated standards. This is more a reflection on the manufacturers’ tolerances than the database ‘accuracy’. We will continue to add to the database as more manufacturers’ figures come available.”
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