We will be interviewing Bryan Litz of Applied Ballistics tomorrow at SHOT Show in Las Vegas. As a sneak preview of some of the topics we’ll cover, here are some highlights of some important, original research conducted by Bryan and his Applied Ballistics team. Bryan wanted to know how much velocity was altered by twist rate. The “real world” test results may surprise you….
The Applied Ballistics team tested six (6) same-length/same-contour Bartlein barrels to observe how twist rate might affect muzzle velocity. This unique, multi-barrel test is featured in the book Modern Advancements in Long Range Shooting. That book includes many other fascinating field tests, including a comprehensive chronograph comparison.
Barrel Twist Rate vs. Velocity — What Tests Reveal by Bryan Litz
When considering barrel twist rates, it’s a common belief that faster twist rates will reduce muzzle velocity. The thinking is that the faster twist rate will resist forward motion of the bullet and slow it down. There are anecdotal accounts of this, such as when someone replaces a barrel of one brand/twist with a different brand and twist and observes a different muzzle velocity. But how do you know the twist rate is what affected muzzle velocity and not the barrel finish, or bore/groove dimensions? Did you use the same chronograph to measure velocity from both barrels? Do you really trust your chronograph?
Savage Test Rifle with Six Bartlein Barrels
Most shooters don’t have access to the equipment required to fully explore questions like this. These are exactly the kinds of things we examine in the book Modern Advancements in Long Range Shooting. In that book, we present experiments conducted in the Applied Ballistics lab. Some of those experiments took on a “Myth Buster” tone as we sought to confirm (or deny) popular pre-conceptions. For example, here’s how we approached the question of barrel twist and muzzle velocity.
Six .308 Win Barrels from Bartlein — All Shot from the Same Rifle
We acquired six (6) barrels from the same manufacturer (Bartlein), all the same length and contour, and all chambered with the same reamer (SAAMI spec .308 Winchester). All these barrels were fitted to the same Savage Precision Target action, and fired from the same stock, and bench set-up. Common ammo was fired from all six barrels having different twist rates and rifling configurations. In this way, we’re truly able to compare what effect the actual twist rate has on muzzle velocity with a reasonable degree of confidence.
Prior to live fire testing, we explored the theoretical basis of the project, doing the physics. In this case, an energy balance is presented which predicts how much velocity you should expect to lose for a bullet that’s got a little more rotational energy from the faster twist. In the case of the .30 caliber 175 grain bullets, the math predicts a loss of 1.25 fps per inch-unit of barrel twist (e.g. a 1:8″ twist is predicted to be 1.25 fps slower than a 1:9″ twist).
Above, data shows relationship between Twist Rate and Muzzle Velocity (MV) for various barrel twist rates and rifling types. From fast to slow, the three 1:10″ twist barrels are: 5R (canted land), 5 Groove, 5 Groove left-hand twist.
We proceeded with the testing in all 6 barrels from 1:8” to 1:12”. After all the smoke cleared, we found that muzzle velocity correlates to twist rate at the rate of approximately 1.33 fps per inch of twist. In other words, your velocity is reduced by about 5 fps if you go from a 1:12” twist to a 1:8” twist. [Editor: That’s a surprising number — much less than most folks would predict.] In this case the math prediction was pretty close, and we have to remember that there’s always uncertainty in the live fire results. Uncertainty is always considered in terms of what conclusions the results can actually support with confidence.
This is just a brief synopsis of a single test case. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests. Results are extrapolated for other calibers and bullet weights. Needless to say, the question of “how twist rate affects muzzle velocity” is fully answered.
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.
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If you have been waiting to purchase a chronograph… now is a great time to buy. You can get the new-model MagnetoSpeed Sporter for under $180.00. You can set up this device in a few minutes, and you never have to go downrange to fiddle with a tripod or fuss with wires. The MagnetoSpeed Sporter is simple and effective — a no-hassle solution.
We’re impressed by the Sporter chrono (as are other shooters — this unit is selling out nationwide). Like the V3, the Sporter faithfully records shots, even in complete darkness. Shot strings are recorded digitally and can be transferred to a smart phone via MagnetoSpeed’s XFR accessory (and Apps).
The MagnetoSpeed Sporter chrono is less than half the price of previous MagnetoSpeed models. This is big news for shooters who always wanted a MagnetoSpeed but found the $379.00 cost (for V3 model) too pricey. The new Sporter Chronograph costs just $179.99 at Sinclair Int’l and Brownells. It offers most of the features of the more expensive models (see chart below for details) and has a updated sensor. MagnetoSpeed says its new Sporter is “Ideal for contoured rifle barrels (sporter barrels) and long-barreled revolvers.” The Sporter Chronograph Kit (shown above) includes: Bayonet Sensor, 3.5 foot Data Cable, Remote Display (with Battery), Strap with thumb nut, Two V-block spacers, and compact storage box.
Is the MagnetoSpeed good enough? Well consider this, Derek Rodgers uses one of the original (full-size) MagnetoSpeed Chronos for his load development. Rodgers is the only man on the planet to have won BOTH the F-Open and the F-TR National Championship. ‘Nuff said.
See MagnetoSpeed Sporter Chronograph Features Reviewed in Video
Q: Will the Sporter Chrono work with thicker barrel (i.e. greater than 1″ diameter)?
A: The manufacturer recommends the $399.00 V3 model for thicker barrels. But, wink-wink, if you have a 1.25″ barrel you can get this to work, based on what we’ve seen.. If you have a really fat barrel (up to 2.0″ diameter), get the V3. Magnetospeed also says the V3 is needed for airguns, shotguns, and muzzleloaders.
Click Image for Full-Screen Photo
The Sporter Chrono attaches quickly and easily. It has a 3.5-foot-long cord, and will work with Muzzle Brakes and Flash-hiders up to 2.7″ long.
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If you have been waiting to acquire a chronograph, it may be time to buy. Brownells.com now has the popular new MagnetoSpeed Sporter Chronograph in stock for just $179.99. This Sporter model shares most of the capabilities of the $399.00 MagnetoSpeed V3, but at a much, much lower cost. Like all MagnetoSpeeds, the Sporter is easy to set up. Just attach the unit to your barrel with a strap and toggle clamp. There is no need to go downrange to set up tripod and skyscreens, or run wires.
We’re impressed by the Sporter chrono (as are other shooters — this unit is selling out nationwide). Like the V3, the Sporter faithfully records shots, even in complete darkness. Shot strings are recorded digitally and can be transferred to a smart phone via MagnetoSpeed’s XFR accessory (and Apps).
What’s the downside? The manufacturer says the Sporter is limited to 1″-max diameter barrels. In actuality, it can go a bit bigger than that. We have used it successfully on a 1.15″ straight contour barrel — but “your mileage may vary”. Second, the manufacturer says the new Sporter is NOT designed for use with airguns or shotguns. We have tested the original MagnetoSpeed with air rifles and it successfully recorded .177 and .22 pellet velocities, once we adjusted the sensitivity.
This Video Shows How to Use the Magnetospeed Sporter Display
Here is the XFR Device that allows Sporter and V3 chronos to work with smartphone Apps:
With MagnetoSpeed’s $24.99 XFR adapter and associated Apps, you can download your current shot series from Sporter and V3 chrono displays to an Android or iOS device. Once synced, users can rename the current shot series, delete irrelevant shots, email the data, reconfigure the display settings (units and sensitivity level), and clear the display’s current series.
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“Shooting Chrony” is a product name. “Shooting Chrony” should not describe (post-mortem) what you have been doing to your chronograph. Sooner or later all of us may make a mistake, and ventilate our chronograph. With luck, the bullet just “wings” your chronograph, and the damage is minor. But if you hit the unit smack dab in the middle, you may have to retire your chrono for good.
A while back, Forum member Jeff M. (aka “JRM850″) experienced a “low blow” that put his Shooting Chrony out of commission. With tongue firmly in cheek, Jeff started a Forum thread entitled Chronograph Not Picking Up Shots in Bright Sunlight Anymore. Looking at the photo below, the problem is obvious.
This was Jeff’s first chrono kill in 23 years of use, so we shouldn’t be too critical. Jeff explained: “I didn’t realize a friend was shifting from a 300-yard target to 100 yards.” The agent of destruction was a low-traveling 58gr V-Max running at 3415 fps. What happened? Well, when one is shooting at 300 yards, the trajectory will be higher than at 100 yards. We should say, however, that this may have been a low shot, or the 100-yard aiming point may have been placed lower to the ground (closer to the bottom of the target frame), as compared to the 300-yard aiming point.
Sporter Chronograph Kit includes: Bayonet Sensor, 3.5 foot Data Cable, Remote Display (with Battery), Strap with thumb nut, Two V-block spacers, and compact storage box.
Magnetospeed has just introduced a new bayonet-style chronograph that is less than half the price of previous MagnetoSpeed models. This is big news for shooters who always wanted a MagnetoSpeed but found the $399.00 cost (for V3 model) too pricey. The new Sporter Chronograph will cost just $189.00. It offers most of the features of the more expensive models (see chart below for details) and has a updated sensor. The MagnetoSpeed Sporter chronograph kit was designed to be used on barrels from 1/2 inch up to 1 inch in diameter. In can also accommodate muzzle brakes and flash hiders up to 2.7 inches in length. MagnetoSpeed says its new Sporter is “Ideal for contoured rifle barrels (sporter barrels) and long-barreled revolvers.”
See $189.00 Sporter Chronograph Features Reviewed in Video
MagnetoSpeed Sporter features
Simple, one-button cycling display (shows recent shot velocity and statistics).
Three sensitivity settings for fine-tuning.
Easy access battery compartment, with 9V Battery included.
Integral, quick-attachment system, with metal buckle, nylon strap, screw-in tensioner, and dual V-block spacers (thick and thin).
Bayonet works with Muzzle Brakes and Flash-hiders up to 2.7″ long.
Q: Will the Sporter Chrono work with thicker barrel (i.e. greater than 1″ diameter)?
A: The manufacturer recommends the $399.00 V3 model for thicker barrels. But, wink-wink, if you have a 1.25″ barrel you can get this to work, based on what we’ve seen. If you need to go really fat (up to 2.0″ diameter), get the V3. Magnetospeed also says the V3 is needed for airguns, shotguns, and muzzleloaders.
Click Image for Full-Screen Photo
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Rick Jensen, Captain of the U.S. F-Open Rifle Team, recently tested some of the new IMR 4451 powder. Rick and other team members were looking for a good powder that could replace Hodgdon 4350 which is difficult to obtain currently. The makers of IMR 4451 claim that it is not sensitive to temperature and that it delivers competitive accuracy. So far, Rick’s tests, done with a .284 Winchester and 180gr Berger Hybrids, appear to confirm those claims. Rick posts:
“I did a little informal powder comparison of H4350 versus the new IMR 4451. Rifle used was a Kelbly Panda with a 30″, 1:8.75″ twist 5R Bartlein barrel [chambered in .284 Win]. All charge weights were 50.0 grains using CCI BR2 primers. I was very impressed with this new powder and I believe it to be equal to H4350 as far as temperature sensitivity.
I did not test for accuracy but I will tell you my groups were pretty much equal between the two and all were in the .2-.3 MOA range. I will defiantly be shooting more of this powder in the weeks to come, assuming the supply chain will allow. It looks very encouraging to finally have a alternative to H4350 that we might actually be able to buy.”
Chronograph Results with Temps from 23° F to 101°
Here are chronograph results of a comparison test between IMR 4451 and H4350. Rick’s rifle was cleaned and allowed to cool between each test. Five fouling shots were fired before each test. Important: Note that for both Test #1 and Test #2, the powder order is reversed in the mid-temp fields (IMR 4451 first, then H4350). For the low and high temp entries, H4350 is listed first.
Here are the IMR 4451 fired cases, displayed Left to right, coldest to the hottest (in terms of case temp when fired). All charge weights were the same: 50.0 grains.
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Grafs.com is now featuring some hard-to-find products that are very popular with our Forum members. These are items that sell out quickly, or may be back-ordered for months. Grab ‘em while you can.
Berger 7mm 180gr Hybrids
Graf’s has the ultra-accurate, high-BC 7mm 180gr Berger Hybrid bullet. This 7mm Hybrid is probably the most popular projectile in use by top F-Class Open shooters. Yes, 7mm Hybrids are in stock now and ready to ship for $45.99 per 100.
Forster Co-Ax Reloading Press
Graf’s has the superb Forster Co-Ax Press in stock and ready to ship. This unique product is the “Cadillac of reloading presses”. Sizing and seating dies slide into universal jaws for quick die changes. The dies can also self-align in the press for reduced run-out on your loaded rounds. If you’ve been wanting a Co-Ax, grab one now as they can be hard to find between production runs.
Magnetospeed V3 Chronograph
Graf’s now sells the remarkable Third Generation Magnetospeed Chronograph. The original Magnetospeed was a “game-changer” in the shooting industry. This compact chrono attaches directly to your barrel so you don’t need to set up a tripod, and fiddle around aligning sky-screens or diffusers. You also don’t have to worry about putting a bullet hole (or two) in the middle of your chronograph. The latest “V3″ model Magnetospeed features an improved attachment system, an upgraded display/control module, plus software enhancements. And Magnetospeed now provides a rugged polymer case that holds the “bayonet” sensing unit, display module, and all other components. Price is $379.99
NOTE: All these prices include shipping with one $7.95 flat fee per order.
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“All dressed up and nowhere to go” was the comment our IT guy, Jay Christopherson, sent with this photo. This is Jay’s testing set-up at his home range, complete with PVM-21 chronograph and wireless target-cam. The camera signal is sent, via WiFi, to Jay’s laptop computer. However, even with all that high-tech electronic gear, you can’t make the shot if you can’t see the target through the rifle-scope. On this morning, heavy ground fog completely obscured the target. Jay told us: “I ended up waiting a little over an hour for the fog to burn off enough so that I could see the 600-yard target. What was funny was that I had a perfectly clear picture of the target via the target-cam and monitor. But there was no way to aim the rifle since the riflescope showed nothing but fog.”
This photo was taken by Jay at the Cascade Shooting Facility in Ravensdale, WA. The rifle is Jay’s .284 Shehane F-Class rifle. Jay was testing primers for Extreme Spread (ES) variation around 9:00 am. Nature was not cooperating. Jay was running Hodgdon H4831sc and testing various primers to see which provided the best numbers.
The chronograph is the Kurzzheit PVM-21. Equipped with infrared sensors, the PVM-21 is our “go-to” chron for most velocity testing, with an Oehler 35P for “back-up”. The PVM-21 (now updated with Kurzzheit’s BMC-19 model) sets up quickly and gives reliable results in any light conditions. But there is something even more sophisticated on the horizon — the new Labradar, a “stand-off” chronograph that uses Doppler radar to measure bullet speed.
Jay explains: “I am (somewhat) patiently waiting for the new Labradar to release. The PVM-21 works pretty well most of the time and is easy to setup. I do get odd readings out of it every so often, but they are pretty obvious when they occur.” The advantage of the Labradar (if it ever comes to market) is that the unit sits to the left or right of the rifle. The Labradar is situated out of the bullet path, so there is no chance of shooting the chronograph by accident. Another advantage of the Labradar is that you can set it up without needing to go forward of the firing line, which would require a safety break.
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Put the same load in a variety of barrels (with the same length and chamberings) and you’ll see a wide variance in muzzle velocity. In fact, it’s not unusual to see up to 100 fps difference from one barrel to the next. We demonstrated this with a comparison test of Lapua factory ammo.
Chron Testing Lapua Factory Ammo
At our Southern California test range, we chronographed Lapua 105gr 6mmBR factory ammo in three different 8-twist barrels of similar length. The results were fascinating. Lapua specs this ammo at 2790 fps, based on Lapua’s testing with its own 26″ test barrel. We observed a speed variance of 67 fps based on tests with three aftermarket barrels.
Brand ‘S’ and Brand ‘PN’ were pre-fit barrels shot on Savage actions. Brand ‘K’ was fitted to a custom action. All test barrels were throated for the 100-108 grain bullets, though there may have been some slight variances in barrel freebore. With a COAL of 2.330″, the rounds were “jumping” to the rifling in all barrels. Among the four barrels, Brand ‘PN’ was the fastest at 2824 fps average — 67 fps faster than the slowest barrel. Roughly 10 fps can be attributed to the slightly longer length (27″ vs. 26″), but otherwise this particular barrel was simply faster than the rest. (Click Here for results of 6mmBR Barrel Length Velocity Test).
Results Are Barrel-Specific, Not Brand-Specific
These tests demonstrate that the exact same load can perform very differently in different barrels. We aren’t publishing the barrel-makers’ names, because it would be wrong to assume that ‘Brand X’ is always going to be faster than ‘Brand Y’ based on test results from a single barrel. In fact, velocities can vary up to 100 fps with two identical-spec barrels from the SAME manufacturer. That’s right, you can have two 8-twist, 26″ barrels, with the same land-groove configuration and contour, from the same manufacturer, and one can be much faster than another.
Don’t Demand More Than Your Barrel Can Deliver
We often hear guys lament, “I don’t get it… how can you guys get 2900 fps with your 6BRs and I can only get 2840?” The answer may simply be that the barrel is slower than average. If you have a slow barrel, you can try using more powder, but there is a good chance it may never run as fast as an inherently fast barrel. You shouldn’t knock yourself out (and over-stress your brass) trying to duplicate the velocities someone else may be getting. You need to work within the limits of your barrel.
Factory Ammo Provides a Benchmark If you have a .223 Rem, 6BR, .243 Win, 6.5×47 Lapua, 6.5×55, .308 Win, 30-06, or 300 WM Rifle, we recommend you buy a box of Lapua factory-loaded ammo. This stuff will shoot great (typically around half-MOA), and it can give you a baseline to determine how your barrel stacks up speedwise. When you complete a new 6BR rifle, it’s wise to get a box of the factory ammo and chronograph it. That will immediately give you a good idea whether you have a slow, average, or fast barrel. Then you can set your velocity goals accordingly. For example, if the factory 6BR ammo runs about 2780-2790 fps in your gun, it has an average barrel. If it runs 2820+ in a 26″ barrel (or 2835 fps in a 28″), you’ve got a fast tube.
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“This new series is heavily based in experimental ballistics, and takes a ‘Myth Busters’-type approach to many of the questions and problems faced by modern long range shooters,” stated Litz. Volume I of the series is scheduled for release in late July, 2014. The book will cost $39.95, but you can pre-order now for $35.95, a 10% savings.
Bryan adds: “Anyone interested in the underlying science behind shooting can benefit from this book. We address the important questions… How much does faster twist affect MV? How does stability affect BC from the muzzle and downrange? What chronographs are capable of high accuracy and precision? What characteristics should you look for in your long range rifle and optic set up? What new gadgets are being developed to enhance long range shooting?
New Book Features Extensive Live-Fire Test Results
Bryan tells us: “The book spotlights state-of-the-art technologies (and methodologies) in long range shooting. New equipment and old ideas are explored using experimental, live-fire testing. Extensive test results are reported in an easy-to-understand way. Among other things, our tests explore the effects of twist rate on muzzle velocity, BC (supersonic and transonic), precision, even spin rate decay for various rifling profiles as they are tested experimentally.
Chronographs and Optics Are Tested and Compared
Litz’s new book traces the evolution of modern rifle, bullet, and optic design. Results from chronograph comparison tests are presented, showing the strengths and weaknesses of available commercial chronographs. High-tech instrumentation such as laser rangefinders and wind measurement devices are explained in detail by contributing author Nick Vitalbo.
The New Book Puts Theory into Practice
We asked Bryan Litz how this new book differs from his previous treatises. Bryan replied: “My original Applied Ballistics for Long-Range Shooting book explains the fundamental elements of external ballistics. It’s the academic background which all future work relies on. The new book, Modern Advancements in Long Range Shooting, covers the ongoing development of equipment and ideas. We explore things like twist rate effects, modern rifle and optic design, and some of the high tech instruments which are being used to enhance the effectiveness of long range shooting.
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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. At the recent Berger Southwest Nationals (SWN), Bryan took top honors among all sling shooters — and he managed to do that while performing many other important match duties. The pay-off for Bryan was getting his name on a really cool “ghost dancer” perpetual trophy. Litz joked: “With what the wind gods can do at shooting matches, it makes sense to have a trophy that puts you in touch with the spirit world.”
This is actually the second time Litz has finished first in Sling class at the Southwest Nationals. After his impressive win, 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”.
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.
Photos by Steve Fiorenzo
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NRA Media recently released a series of informative videos about the Science of Shooting. These videos feature high production values, with super-slow motion segments, as well as helpful computer graphics to illustrate the principles covered.
The videos are narrated by our friend Jessie Duff, a top action pistol shooter (and the first women ever to achieve USPSA Grand Master status). Jessie is assisted by talented shooters such as Top Shot Season 4 Champion Chris Cheng.
There are eight (8) videos in the Firearm Science Video Series. Here are two videos, with links to the rest below.
RECOIL — The Physics of Recoil Explained
While this video focuses on handguns, the principles involved apply to all firearms. The force of recoil is affected by the mass of the firearm, and by the speed and weight of the projectile. On a revolver, as shown in the video, there are various phases of recoil. Grip, and “compensation” porting can change the perceived force of recoil (though the energy is constant for any given ammunition specification).
VELOCITY — Calculating the Speed of a Bullet
This video shows a conventional chronograph with front and rear light sensors. The bullet first trips the front sensor and then the rear sensor as it flies over the unit. The difference in sensor time is used to calculate bullet speed. This is not the only kind of chrono in common use today. The popular MagnetoSpeed chrono works by tracking the bullet as it passes over two magnetic sensors mounted on a bayonet-style fixture on the barrel. Steinert Sensing Systems offers an Acoustic Chronograph that works by measuring the bullet’s supersonic shock-wave. This system has a much larger “sweet spot” than most optical chronographs. Last (but certainly not least) is the brand new Doppler Radar chronograph from MyLabradar.com. This can measure the speed of a bullet without the need to send the round directly over sensors.
Interestingly, this video also explains how, in the days before electric lamps, digital processors, and radar, scientists used a mechanical “Ballistic Pendulum” to calculate bullet velocity using Newtonian physics. The Ballistic Pendulum was first used in the mid 1700s. We have come a long way since then.
This is just a brief synopsis of a single test case. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests. Results are extrapolated for other calibers and bullet weights. Needless to say, the question of “how twist rate affects muzzle velocity” is fully answered.
“I did a little informal powder comparison of H4350 versus the new IMR 4451. Rifle used was a Kelbly Panda with a 30″, 1:8.75″ twist 5R Bartlein barrel [chambered in .284 Win]. All charge weights were 50.0 grains using CCI BR2 primers. I was very impressed with this new powder and I believe it to be equal to H4350 as far as temperature sensitivity.
If you have a .223 Rem, 6BR, .243 Win, 6.5×47 Lapua, 6.5×55, .308 Win, 30-06, or 300 WM Rifle, we recommend you buy a box of 
NRA Media recently released a series of informative videos about the Science of Shooting. These videos feature high production values, with super-slow motion segments, as well as helpful computer graphics to illustrate the principles covered.
