Shooter behind the .375 Lethal Magnum. Check out the size of that suppressor!
Two-Mile ELR Training The Applied Ballistics ELR Team spent the weekend at the NRA Whittington Center in New Mexico training for the upcoming King of 2 Miles event. Former USAMU coach Emil Praslick III was on hand to help with wind calls. The results were impressive — all team members had confirmed hits at 2.05 miles on a 36″x36″ steel target. Bryan Litz even had a 3-shot group that measured 17.5″ x 22″. That’s under 0.6 MOA!
Most guys would be happy with 0.6 MOA at 300 yards. Bryan did it at 3611 yards, shooting Paul Phillips’s .375 Lethal Magnum. When you consider all the variables involved (bullet BC variance, shot velocity variance, wind changes during flight, Coriolis effect etc.), that’s phenomenal.
Report by Paul Phillips
Just got done shooting two days in New Mexico with Recoil Magazine and the Applied Ballistics ELR team. We learned a lot and had great success. Every team member made impacts on target at 2 miles. The best 3-shot group at 3611 yards (2.05 miles) was shot by Bryan Litz with my 375 Lethal Mag. The group measured 17.5 inches tall by 22 inches wide with Cutting Edge bullets. We also had Recoil’s David Merrill shoot at two miles and was laying them in there like a true pro. We had three team members make impacts on the 36-inch plate at two miles within just three attempts in a mock competition. I also increased my personal longest shot by hitting only 15 inches right of center at 3611 yards. 2.05 miles. I did it with a GSL Technology Copperhead Silencer.
Report by Emil Praslick
I participated in the Extreme Long Range training with the Applied Ballistics team at the Whittington Center in Raton, NM. All team members had confirmed hits at 2.1 miles. Components and hardware suppliers included: Berger Bullets, Cutting Edge Bullets, Nightforce Optics, Kestrel, FLIR Systems.
Q: At that distance (2.1 miles), how much do spin drift and the Coriolis effect impact bullet trajectories?
Praslick: At 3613 yards we had to adjust about 1.5 MOA/56″ of Coriolis (up), and 5 MOA/~190″ of right spin drift adjustment. You’d have to come down if facing East. The planet rotates counter-clockwise (from above), so your target would be falling away from you.
Here is a 3-round group at 1898 yards (1.08 Miles) shot with factory ABM Ammo .338 Lapua Magnum loaded with 300 grain Berger Bullets Hybrids. That’s sub-MOA elevation. (The guy calling wind didn’t do too bad, either.)
Report by Bryan Litz
Learning is my favorite part of new ventures and we learned a LOT this weekend shooting extreme range in New Mexico. I connected on a second round hit on a 3-foot square target at 2 miles in simulated match conditions under coaches Emil Praslick and Paul Phillips. In fact all five of our team shooters got on at 2 miles. The Applied Ballistics Extreme Long Range team is in good shape for the King of 2 Miles match later this month, and there is still so much to LEARN!
You need serious equipment for shooting beyond two miles. Who can identify this high-tech hardware?
Any long range shooter knows that wind is our ultimate nemesis. The best ways of overcoming wind are to measure what we can and use computers to calculate deflection. The Applied Ballistics Kestrel is a great tool for this. As good as our tools may be, we don’t always have them at our fingertips, or they break, batteries go dead, and so on. In these cases, it’s nice to have a simple way of estimating wind based on known variables. There are numerous wind formulas of various complexity.
The Applied Ballistics (AB) Wind Hack is about the simplest way to get a rough wind solution. Here it is: You simply add 2 to the first digit of your G7 BC, and divide your drop by this number to get the 10 mph crosswind deflection. For example, suppose you’re shooting a .308 caliber 175-grain bullet with a G7 BC of 0.260 at 1000 yards, and your drop is 37 MOA. For a G7 BC of 0.260, your “wind number” is 2+2=4. So your 10 mph wind deflection is your drop (37 MOA) divided by your “wind number” (4) = 9.25 MOA. This is really close to the actual 9.37 MOA calculated by the ballistic software.
WIND HACK Formula
10 mph Cross Wind Deflection = Drop (in MOA) divided by (G7 BC 1st Digit + 2)
Give the AB wind hack a try to see how it works with your ballistics!
Some Caveats: Your drop number has to be from a 100-yard zero. This wind hack is most accurate for supersonic flight. Within supersonic range, accuracy is typically better than +/-6″. You can easily scale the 10 mph crosswind deflection by the actual wind speed. Wind direction has to be scaled by the cosine of the angle.
Getting started in long-range shooting? Need some pointers on gun set-up and hardware options? Bryan Litz of Applied Ballistics has created a helpful series of videos for the NSSF covering long range shooting. Bryan, 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 2016 King of 2 Miles event. Here are four (4) videos, each covering a topic of interest for long-range shooters. Running 3-4 minutes each, these videos can help you get started, and invest wisely when acquiring your next long-range rifle, scope, and accessories.
Long Range Precision — The Keys to Success
TIP for Plotting Long Range Trajectories: You want to know the true, actual ballistic coefficients of your loads. The BCs listed by manufacturers for their projectiles may be somewhat unreliable — the real BC could be higher or lower (and BC can change with velocity). That can result in problems at longer distances. Using sophisticated equipment, Applied Ballistics has measured true BCs for hundreds of projectiles. Plugging these verified numbers into your Ballistics App can improve your hit percentage at long range.
Tools of Choice — Purpose-Built Long Range Rifles
TIP for Choosing a Rifle: When you’re selecting a rifle for long range shooting, it’s important to understand your application and objectives. The applications for long-range shooting can be very refined. You have to select all the details of your application to select the correct rifle. Here are two examples — a semi-auto AR-platform rifle with scope and a bolt-action Fullbore (Palma) rifle with aperture sights. There are many other long range disciplines — F-TR for example. The F-TR rig uses a bipod and rear bag and a scope. To be competitive, a modern F-TR rig should shoot well under half-MOA.
Equipment Advice — Upgrading Your Hardware
TIP for Upgrading Your Rifle: At some point factory rifle owners will recognize weak links in the equipment chain. You can run that factory rifle for quite some time, but the barrel is eventually what’s going to hold you back. The twist-rate may not be high enough to stabilize the high-BC bullets. So the first thing you’re going to want to upgrade is the barrel. You want to get a fast twist-rate barrel with a chamber that is optimized for the bullet you’ll be shooting. A good-quality, custom barrel will be easier to clean, and it will improve the overall accuracy and precision of your shooting.
Big Boomers — Large-Caliber Rifles for Long Range
TIP for Shooting Hard-Recoiling Rifles: Bryan Litz defines “Large Caliber” as .338 caliber and bigger. These rifles can shoot heavy bullets with high BCs. However there are some trade-offs. It can be hard to maintain good fundamentals of marksmanship (trigger control, sight alignment) when you’re fighting heavy recoil and burning 100+ grains of powder. You’re dealing with the challenges that high energy brings. You want a muzzle brake with any cartridge .338 or above. Also, when considering lathe-turned solid bullets, remember that these typically have less sectional density compared to lead-cored bullets with similar profiles. This affects ballistics as well as recoil energy.
There’s a new home on the web for Extreme Long Range (ELR) shooters. Bryan Litz and Applied Ballistics recently launched ELR Central, a new website dedicated to ultra-long-range shooting*. This new site will offer a wide variety of information. Bryan Litz explains: “The most visible element of ELR Central will be a website which will serve to publish and promote all ELR shooting events going on across the country. Although owned and operated by Applied Ballistics, ELR Central will rely heavily on input from the community in order to best serve the sport as a whole.” Along with the ELR Central website, Applied Ballistics has launched a new ELR Central Facebook page.
Content Available on ELR Central
The ELR Central website will eventually offer a comprehensive library of information and activity reports. Bryan and his team plans to build out the website to include all the following:
1. Map of ELR ranges across the USA.
2. List of ELR events with links to the Match Directors’ pages.
3. Technical information and articles for the ELR community.
4. Match results/reports, including equipment lists where available.
5. Analysis of what equipment and shooters are doing well in ELR.
6. Links to other ELR shooting resources such as forums and websites.
On 5/13/17, the Applied Ballistics ELR Team had a successful practice at 3161 Yards (1.8 miles). Bryan Litz reports: “The main goal … was to test how the Berger and Cutting Edge bullets traveled through transonic and subsonic speeds. We all made several hits on target and several within 1 MOA of center.”
Standardized ELR Targets
Another goal of ELR Central is to develop standardized ELR targetry. Bryan explains: “In competitive rifle shooting, standardization of targetry is important. Applied Ballistics, through ELR Central, will provide steel targets to organizations wishing to run ELR matches and/or record-setting events. No one would be required to use these standard targets, we’re simply providing resources to help promote promote some consistency.” The initial standard target, produced by MGM Targets, will be a steel square, 3 feet (36″) per side.
ELR Central is Not A Rule-Making Entity
Bryan was quick to explain that ELR Central is not a governing body, but rather it was created to help advance the sport (and science) of shooting at very long distances, one mile and beyond: “The concept of ELR Central is a result of the ongoing discussions about standardizing ELR matches, records, targets, and more. Although ELR Central will not be enforcing these details, there is a measure of organization which we feel is appropriate, would benefit the sport, and that we are willing to provide. ELR Central is NOT a governing or sanctioning body. We do not have nor seek the authority to dictate how matches are run. For anyone who asks, we can advise on best practices, and what’s generally working, but we’re not here to tell anyone what to do nor how to do it.”
More Information on ELR Competition, per ELR Researcher:
(1) By consensus of the parties involved in the ELR meetings held at SHOT this year, and notwithstanding the names and descriptions of certain “ELR” web sub-forums, “ELR” has been defined as “beyond 1500 yards”.
(2) ELR Central-recognized “ELR” events require that more than one-half of targets must be beyond 1500 yards. Where all criteria are not met an event may be promoted as having “ELR components”.
(3) “ELR Central has published a set of guidelines and standards by which official world records can be established.” CLICK HERE for guidelines/standards.
Story tip from EdLongrange. We welcome reader submissions.
Need a top-notch Ballistics App for your iPhone, iPad, or iPod? Start with Ballistic AE, the number 1 (i.e. most installed) App for iOS systems. Ballistics AE (Advanced Edition) is the most popular iOS ballistics program for many good reasons. Full-featured and easy to use, Ballistics AE has been refined over many years, and it supplies rock-solid solutions derived from JBM Ballistics solver (created by James B. Millard). Unlike some other Apps, Ballistics AE is STABLE on iPhones (with various OS levels). What’s cool is that Ballistics AE is now on sale for $12.99.
We’ve used the Ballistic AE program on an iPhone 5S, iPhone 6, and iPad, and it performed well. Here are some of the features we liked:
1. Mirrors output from online version of JBM Ballistics we often use for initial calculations.
2. Controls are simple to use and (mostly) intuitive.
3. Handy comparison feature lets you compare ballistics for different projectiles side by side.
4. Advanced Wind Kit allows you to account for complex wind situations.
5. Projectile and BC Database is very comprehensive.
6. Software is regularly updated to match Apple OS changes.
Comprehensive Projectile Info and BCs
Ballistics AE has very complete data libraries. The program includes 5,000 projectiles, factory loads, military loads, and performance data points from leading manufacturers, military testing, and performance testing.
Ballistic Coefficient libraries include the latest commercial BC data, plus Applied Ballistics’ (Bryan Litz) custom G7 BCs, plus G7 military coefficients from Aberdeen Proving Grounds.
These Videos Explain How to Set Up and Use Ballistic AE:
There’s a great interview with Bryan Litz of Applied Ballistics on Mia Rhode’s Life Of A Shooter’s Wife Blog. We recommend you read the full interview. Bryan offers many important insights that can benefit any precision shooter. It’s fascinating to learn about Bryan’s background and how he progressed in competitive shooting, starting with very basic equipment. As a “broke high school kid”, he got started on the cheap, paying for gear with wages from McDonald’s. Now he’s a globally-recognized expert in Ballistics and Long Range precision. You’ll enjoy reading the Full Interview. Here are some highlights…
LOASW: When did you first become interested in shooting?
Bryan: My first memories of shooting were at the age of about 9 or 10. Pellet rifle in the back yard. My Dad taught me to shoot, stressing the importance of accuracy. I was driven to hit targets, mostly small targets at long distance. My grandfather was on the All-Army shooting team back in the ‘50s, and was distinguished in both rifle and pistol. Shooting is part of my family’s DNA and I benefited from that from a young age.
LOASW: What sparked your interest in Competitive Shooting and how old were you when you started competing?
Bryan: Hunting groundhogs in the farm-fields of Pennsylvania through high school is where I truly connected with long-range shooting. My Dad heard of a competition range (The Original Pennsylvania 1000 Yard Benchrest Club in Williamsport, PA). So we visited there one summer and I immediately found my trusty 22-250 inadequate for the job of 1000-yard benchrest shooting. So I saved my McDonald’s wages until I could afford a 7mm Remington Magnum and began competing in my first matches at the age of 15.
Learning with Limited Resources…
… It was a huge mis-match to my situation because benchrest is a highly gear-driven sport, and the winners typically have many $1000s of dollars wrapped up in equipment. I was a broke high school kid who needed my parents to drive me to the range my first year, and my second year, I had to rely on fellow competitors to jump start my old pick-up truck that was always breaking down. Nevertheless I enjoyed the hell out of shooting 1000 yards. I can honestly say that I don’t have any more FUN shooting these days with all the best equipment as compared to those bad ‘ol days when I had maybe $900 total wrapped up in all my gear. Those who remember me from those early days might recall the home-made shooting rest and McDonalds French fry box that I carried all my gear in. Later when I picked up prone/sling shooting, my shooting mat was a piece of carpet (pink, no less), and my shooting coat was a military field jacket with belts sewn in it.
Money was probably my biggest challenge when I started out. I had plenty of fun with my budget kit, but was certainly constrained by lack of access to quality gear. I overcame this with hard work and making the most of what I had. Learning how to mitigate the deficiencies of my equipment was an important stepping stone which has been highly valuable even now when I’ve got better stuff. It’s a good skill to have, to be able to spot something about to come unraveled.
LOASW: What advice would you give to someone new to competitive shooting?
Bryan: Find a mentor, someone who lives near you who has experience and is willing to share it. You will cut years off your learning curve if you can get someone to share their experience with you who’s “been there done that”.
You may not realize it… but to get the optimum BC from your bullets (i.e. the lowest aerodynamic drag), you must spin the bullets fast enough. Bullet drag increases (as expressed by lower BC) if the bullet spins too slowly. Bryan Litz of Applied Ballistics explains how BC changes with twist rates…
More Spin, Less Drag
In this article, we look at how twist rate and stability affect the Ballistic Coefficient (BC) of a bullet. Again, this topic is covered in detail in the Modern Advancements book. Through our testing, we’ve learned that adequate spin-stabilization is important to achieving the best BC (and lowest drag). In other words, if you don’t spin your bullets fast enough (with sufficient twist rate), the BC of your bullets may be less than optimal. That means, in practical terms, that your bullets drop more quickly and deflect more in the wind (other factors being equal). Spin your bullets faster, and you can optimize your BC for best performance.
Any test that’s designed to study BC effects has to be carefully controlled in the sense that the variables are isolated. To this end, barrels were ordered from a single barrel smith, chambered and headspaced to the same rifle, with the only difference being the twist rate of the barrels. In this test, 3 pairs of barrels were used. In .224 caliber, 1:9” and 1:7” twist. In .243 caliber it was 1:10” and 1:8”, and in .30 caliber it was 1:12” and 1:10”. Other than the twist rates, each pair of barrels was identical in length, contour, and had similar round counts. Here is a barrel rack at the Applied Ballistics Lab:
Applied Ballistics used multiple barrels to study how twist rate affects BC.
“The Modern Advancements series is basically a journal of the ongoing R&D efforts of the Applied Ballistics Laboratory. The goal of the series is to share what we’re learning about ballistics so others can benefit.” –Bryan Litz
Barrel twist rate along with velocity, atmospherics, and bullet design all combine to result in a Gyroscopic Stability Factor (SG). It’s the SG that actually correlates to BC. The testing revealed that if you get SG above 1.5, the BC may improve slightly with faster twist (higher SG), but it’s very difficult to see. However, BC drops off very quickly for SGs below 1.5. This can be seen in the figure below from Modern Advancements in Long Range Shooting.
The chart shows that when the Gyroscopic Stability Factor (SG) is above 1.5, BC is mostly constant. But if SG falls below 1.5, BC drops off dramatically.
Note that the BC drops by about 3% for every 0.1 that SG falls below 1.5. The data supports a correlation coefficient of 0.87 for this relationship. That means the 3% per 0.1 unit of SG is an accurate trend, but isn’t necessarily exact for every scenario.
It’s a common assumption that if a shooter is seeing great groups and round holes, that he’s seeing the full potential BC of the bullets. These tests did not support that assumption. It’s quite common to shoot very tight groups and have round bullet holes while your BC is compromised by as much as 10% or more. This is probably the most practical and important take-away from this test.
To calculate the SG of your bullets in your rifle, visit the Berger Bullets online stability calculator. This FREE calculator will show you the SG of your bullets, as well as indicate if your BC will be compromised (and by how much) if the SG is below 1.5. With the stated twist rate of your barrel, if your selected bullet shows an SG of 1.5 (or less), the calculator will suggest alternate bullets that will fully stabilize in your rifle. This valuable online resource is based directly on live fire testing. You can use the SG Calculator for free on the web — you don’t need to download software.
Learn More About SG and BC This article is just a brief overview of the interrelated subjects of twist rate, Gyroscopic Stability, and BC. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests.
Other chapters in the book’s twist rate section include: · Stability and Drag – Supersonic
· Stability and Drag – Transonic
· Spin Rate Decay
· Effect of Twist rate on Precision
Other sections of the book include: Modern Rifles, Scopes, and Bullets as well as Advancements in Predictive Modeling. This book is sold through the Applied Ballistics online store. Modern Advancements in Long Range Shooting is also available in eBook format in the Amazon Kindle store.
In this video Bryan Litz of Applied Ballistics offers tips on Big Bore shooting (i.e. .338 caliber and above). Bryan offers advice on bullet selection and he explains the challenge of handling the blast, noise, concussion, and recoil of big boomers such as the .416 Barrett and .50 BMG.
Bryan goes big … very big, shooting a monster .50 BMG bullpup.
Watch the recoil pulse shove Bryan backwards at 1:40 time-mark:
Big Bore Basics — Tips for Shooting Big Boomersby Bryan Litz
There are some unique things to consider with big-bore shooting. One is bullet design. For long-range shooting you want high-BC bullets. You get high BC from heavy bullets and bullets that have low drag. The interesting trade-off in big calibers is that there are a lot more lathe-turned solid bullets in copper and brass available than there are in the smaller calibers. You’ve got bullets that have slightly lower drag profiles but they are made of materials that are slightly less dense (than lead) so they are relatively light for their caliber. With that trade-off, the BCs might not be as high as you think for big calibers, although the bullets are heavy enough that they carry a lot of energy.
Energy really has a lot to do with shooting these big-caliber rifles. As with any kind of shooting, the fundamentals of marksmanship are the most important thing. However, it can be hard to maintain good fundamentals (e.g. trigger control and sight alignment) when you’re burning 100 grains of powder. There’s a lot of concussion (you want a muzzle brake no matter what your cartridge is above .338). It certainly can be challenging with all the muzzle blast and all the energy coming out of the barrel.
For long-range shooting with big bore rifles, you are still looking for the same things that you want with smaller-caliber rigs. You want a high-performance bullet, you want consistent ammunition, and you want a good fire solution to be able to center your group at long range. Basically you’re just dealing with the challenges that the high energy brings, and being smart about your bullet selection.
In the video above, Bryan is shooting the DesertTech HTI bullpup. This rifle can shoot four (4) big bore chamberings, with barrel conversion kits for: .375 CheyTac, .408 CheyTac, .416 Barrett, and .50 BMG. These can be quickly swapped in the HTI chassis, which employs an internal barrel-clamp system.
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).
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.
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.”
Verifying 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.
Applied Ballistics has produced a series of YouTube videos about precision long range shooting. Featuring ace long-range shooter and professional ballistician Bryan Litz, these videos address various topics of interest to long-range marksmen. This featured video looks at Long Range mistakes — Bryan Litz reveals the most common ballistics-related shooting errors at Long Range. And then Bryan explains how to improve your shooting (and wind reading) to eliminate those common errors.
Watch Applied Ballistics Video about Common Mistakes in Long Range Shooting:
Bryan Litz of Applied Ballistics often hears the question: “What are the main reasons people miss their target at long range?” To answer that question, in this video, Bryan explains the most important variables in Long Range shooting. Bryan says: “Probably the number one thing is range — you have to have a [precise] range to your target because your bullet is dropping, and to hit the target you need to correct for bullet drop.” Distance may be indicated on the target bay (or berm), but for open ranges you should ascertain distance-to-target with a quality laser rangefinder. Even when the distance to target is shown with a sign or marker, you may want to confirm the distance with your rangefinder. (You may be surprised — we’ve seen marked target distances at commercial ranges off by 25+ yards!) Bryan says: “Get a good laser range to the target and you’ll be within a couple yards”.
After distance to target, the most important variable is the wind. This is the most challenging factor because the wind is constantly changing. Bryan explains: “After 300 or 400 yards, the wind [will] move your shots off the target if you don’t correct for it. The best way to account for the wind is to measure it at your location with a Kestrel. The Kestrel can give you the speed and direction of the wind at your location, which can baseline your wind call for your long-range shot.” Bryan acknowledges that there will still be variables: “The wind isn’t always blowing the same downrange as at your location… and the wind is always changing”. Bryan notes that you need to account for variances in wind between the time you gauge the wind angle and velocity and the time you actually you take your shot.