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 some years ago, 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.
Barrel Velocity Variance
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).
IMPORTANT: 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, 6mmBR, .243 Win, 6.5×47 Lapua, 6.5 Creedmoor, 6.5×55, .308 Win, .30-06 Springfield, or .338 LM 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. [Editor’s NOTE: The original test was conducted in 2008. The velocity of current-production Lapua factory ammo might be higher or lower, so your results may vary.]
When you complete a new 6mmBR rifle, it’s definitely smart 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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If you are planning to shoot a PRS match with factory ammo or use factory ammo when hunting, you should definitely check the ammo velocity in YOUR rifle. Otherwise your ballistics come-up tables could be all wrong. It’s not uncommon to find that the actual velocity in YOUR gun is NOT the same as the listed velocity on the ammunition package. We explain why in today’s article…
Why You CANNOT Rely on the MV Printed on the Ammo Box!
When figuring out your come-ups with a ballistics solver or drop chart it’s “mission critical” to have an accurate muzzle velocity (MV). When shooting factory ammo, it’s tempting to use the manufacturer-provided MV which may be printed on the package. That’s not such a great idea says Bryan Litz of Applied Ballistics. Don’t rely on the MV on the box, Bryan advises — you should take out your chrono and run your own velocity tests. There are a number of reasons why the MV values on ammo packaging may be inaccurate. Below is a discussion of factory ammo MV from the Applied Ballistics Facebook Page.
Five Reasons You Cannot Trust the Velocity on a Box of Ammo:
1. You have no idea about the rifle used for the MV test.
2. You have no idea what atmospheric conditions were during testing, and yes it matters a lot.
3. You have no idea of the SD for the factory ammo, and how the manufacturer derived the MV from that SD. (Marketing plays a role here).
4. You have no idea of the precision and quality of chronograph(s) used for velocity testing.
5. You have no idea if the manufacturer used the raw velocity, or back-calculated the MV. The BC used to back track that data is also unknown.
1. The factory test rifle and your rifle are not the same. Aside from having a different chamber, and possibly barrel length some other things are important too like the barrel twist rate, and how much wear was in the barrel. Was it just recently cleaned, has it ever been cleaned? You simply don’t know anything about the rifle used in testing.
2. Temperature and Humidity conditions may be quite different (than during testing). Temperature has a physical effect on powder, which changes how it burns. Couple this with the fact that different powders can vary in temp-stability quite a bit. You just don’t know what the conditions at the time of testing were. Also a lot of factory ammunition is loaded with powder that is meter friendly. Meter friendly can often times be ball powder, which is less temperature stable than stick powder often times.
3. The ammo’s Standard Deviation (SD) is unknown. You will often notice that while MV is often listed on ammo packages, Standard Deviation (normally) is not. It is not uncommon for factory ammunition to have an SD of 18 or higher. Sometimes as high as 40+. As such is the nature of metering powder. With marketing in mind, did they pick the high, low, or average end of the SD? We really don’t know. You won’t either until you test it for yourself. For hand-loaded ammo, to be considered around 10 fps or less. Having a high SD is often the nature of metered powder and factory loads. The image below is from Modern Advancements in Long Range Shooting: Volume II.
4. You don’t know how MV was measured. What chronograph system did the manufacturer use, and how did they back track to a muzzle velocity? A chronograph does not measure true velocity at the muzzle; it simply measures velocity at the location it is sitting. So you need to back-calculate the distance from the chrono to the end of the barrel. This calculation requires a semi-accurate BC. So whose BC was used to back track to the muzzle or did the manufacturer even do that? Did they simply print the numbers displayed by the chronograph? What kind of chronograph setup did they use? We know from our Lab Testing that not all chronographs are created equal. Without knowing what chronograph was used, you have no idea the quality of the measurement.
5. The MV data may not be current. Does the manufacturer update that data for every lot? Or is it the same data from years ago? Some manufacturers rarely if ever re-test and update information. Some update it every lot (ABM Ammo is actually tested every single lot for 1% consistency). Without knowing this information, you could be using data for years ago.
CONCLUSION: Never use the printed MV off a box of ammo as anything more than a starting point, there are too many factors to account for. You must always either test for the MV with a chronograph, or use carefully obtained, live fire data. When you are using a Ballistic Solver such as the AB Apps or Devices integrated with AB, you need to know the MV to an accuracy down to 5 fps. The more reliable the MV number, the better your ballistics solutions.
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The Magnetospeed V3 chronograph is affordable, easy to transport, and easy to set up. With a MagnetoSpeed barrel-mounted chrono you can quickly and easily record muzzle velocity (MV) without having to set up tripods or walk down-range. The compact MagnetoSpeed chronos are easy to operate and transport. With the full-featured V3 model, everything you need comes in a small fitted case. In the top photo are the components used with the MagnetoSpeed V3 Kit:
1. V3 Bayonet sensor
2. Display and control unit
3. Bayonet spacers (plastic and rubber)
4. Cords and mounting hardware (left), suppressor heat shield (right)
5. Alignment rod (square cross-section)
6. Rail adapter (sold separately)
Our friend Gavin Gear of UltimateReloader.com reviewed the MagnetoSpeed V3 and came away impressed. Gavin explains that a good chrono is essential: “If you want to load and shoot precision ammunition, you need the tools that will produce and validate the precision of your loads. A good chronograph is one of those tools! In this post I’m going to introduce you to the MagnetoSpeed V3 chonograph, the high-end electromagnetic chronograph which fills out the top slot in MagnetoSpeed’s equipment portfolio.”
In this 11-minute video Gavin reviews MagnetoSpeed’s top-of-the-line V3 Chronograph. He shows what ships with the unit, how to set it up for both rifles and pistols, and then he puts it through its paces showing how it captures velocity data. Gavin says he will follow-up with future videos showing how to link the MagnetoSpeed V3 to your mobile phone and how to log velocity data for future reference. To learn more about this high-tech chrono, visit UltimateReloader.com.
Given its compact size, reasonable price, and easy of set-up, we believe all serious shooters should have a MagnetoSpeed in their gear collection even if their primary chronograph is a LabRadar. The MagnetoSpeed V3 complete system is available now for $399.99 from Sportsman’s Warehouse (MSRP is $449.00). A Labadar Chrono by itself is $625.00 but they are currently out-of-stock.
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The Magnetospeed V3 chronograph is affordable, easy to transport, and easy to set up. With a MagnetoSpeed barrel-mounted chrono you can quickly and easily record muzzle velocity (MV) without having to set up tripods or walk down-range. The compact MagnetoSpeed chronos are easy to operate and transport. With the full-featured V3 model, everything you need comes in a small fitted case. In the top photo are the components used with the MagnetoSpeed V3 Kit:
1. V3 Bayonet sensor
2. Display and control unit
3. Bayonet spacers (plastic and rubber)
4. Cords and mounting hardware (left), suppressor heat shield (right)
5. Alignment rod (square cross-section)
6. Rail adapter (sold separately)
Our friend Gavin Gear of UltimateReloader.com reviewed the MagnetoSpeed V3 and came away impressed. Gavin explains that a good chrono is essential: “If you want to load and shoot precision ammunition, you need the tools that will produce and validate the precision of your loads. A good chronograph is one of those tools! In this post I’m going to introduce you to the MagnetoSpeed V3 chonograph, the high-end electromagnetic chronograph which fills out the top slot in MagnetoSpeed’s equipment portfolio.”
In this 11-minute video Gavin reviews MagnetoSpeed’s top-of-the-line V3 Chronograph. He shows what ships with the unit, how to set it up for both rifles and pistols, and then he puts it through its paces showing how it captures velocity data. Gavin says he will follow-up with future videos showing how to link the MagnetoSpeed V3 to your mobile phone and how to log velocity data for future reference. To learn more about this high-tech chrono, visit UltimateReloader.com.
Given its compact size, reasonable price, and easy of set-up, we believe all serious shooters should have a MagnetoSpeed in their gear collection even if their primary chronograph is a LabRadar. The MagnetoSpeed V3 complete system is available now for $399.99 from Shop.GoHunt.com (MSRP is $449.00).
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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 some years ago, 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.
Barrel Velocity Variance
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).
IMPORTANT: 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, 6mmBR, .243 Win, 6.5×47 Lapua, 6.5 Creedmoor, 6.5×55, .308 Win, .30-06 Springfield, or .338 LM 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. [Editor’s NOTE: The original test was conducted in 2008. The velocity of current-production Lapua factory ammo might be higher or lower, so your results may vary.]
When you complete a new 6mmBR rifle, it’s definitely smart 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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If you have been waiting to purchase a chronograph… now is a great time to buy. You can get the reasonably-priced MagnetoSpeed Sporter for $249.00. 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.
See MagnetoSpeed Sporter Chronograph Features Reviewed in Video
We’re impressed by the Sporter chrono, as are other shooters — this unit is very popular. Like the MagnetoSpeed 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 offers most of the features of the more expensive models (see chart below for details) and has a updated sensor. MagnetoSpeed says the 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.
Q: Will the Sporter Chrono work with thicker barrel (i.e. greater than 1″ diameter)?
A: The manufacturer recommends the $449.00 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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SUMMARY: This article reviews a device that “triggers” the LabRadar chronograph to register bullet speed. Rather than activate by sound or Doppler reading, this $35 JKL Inertial Trigger works from the rifle’s instantaneous recoil pulse when a shot is fired. After some frustration with his LabRadar when shooting at a range with reflective surfaces, our tester is now reporting that 100% of his actual shots are being captured correctly by his LabRadar chrono equipped with the JKL Inertial Trigger. He won’t use his LabRadar without it now. Other users have become instant fans of this inertial LabRadar trigger as well. It is very affordable and it works great. VIEW LARGE PHOTO.
JKL Inertial Trigger for LabRadar Chronograph
Product Review by F Class John
The LabRadar chronograph has been one of the most revolutionary tools in the shooting world because of how it collects velocity data, how it reports (and stores) that data, and, ultimately, the ease with which it can be positioned and operated. However, it’s not a perfect system. A majority of the complaints come from users whose LabRadars sometimes fail to record all the shots fired in a string. For the average plinker, this may not be an issue. But for serious shooters trying to do ladder tests or load development requiring all shots to be reported, it can be frustrating when a shot is missed.
Traditionally, LabRadar has recommended trying different settings that compensate for the gap between the unit and muzzle as well as well as having different options for how the unit recognizes a shot fired. While these options work to some degree, they aren’t a guaranteed fix especially when shooting at ranges with concrete baffles or with roofs, walls, and dividers that can alter sound waves. While nobody can precisely explain why shots are lost under certain circumstances, the fact remains it DOES happen. In addition, the default system can sometimes pick up stray shots from nearby rifles.
Not willing to give up on this sophisticated chronograph, many shooters have looked for a foolproof way to prevent such failures from happening. In fact, for this shooter, the frustration was so high that I actually sold my first LabRadar and went back to another chronograph before ultimately buying another LabRadar almost a year later. But I made that repeat purchase only after vowing to finding a way to make the LabRadar work — EVERY time, for EVERY shot.
See How JKL Inertial Trigger Works in this Video
JKL Inertial Trigger — Outstanding Product That Works Great
Enter the JKL Gen 2 Trigger for the LabRadar. This is an easy-to-use, inertial-driven trigger that activates simply from the recoil of your gun. The unit consists of a small rectangular pad attached to a long audio cable. All you do is plug in the audio cable, attach the pad to your gun with the provided hook and loop (Velcro) material. Then (important), you must change the LabRadar trigger settings from “Doppler” to “Trigger”. The unit works great and is easy to set up. In my experience, the unit will activate no matter where you place it on a stock. However the recoil of every gun is slightly different, so you will need to make sure you find a location that doesn’t interfere with your shooting setup.
An unexpected benefit of using the JKL trigger is that it gives you a larger area in which to place your Labradar unit, making it more convenient to setup on benches or range stations. I found this a welcome relief since the LabRadar originally seemed somewhat fussy about where I placed it. Now I can place the LabRadar in more convenient locations — as long as it’s still near my gun and pointed at the target correctly, I get consistent bullet speed data.
Are There Issues with “False Positives”?
If there is any downside to using the JKL Inertial Trigger, it’s that a very hard bump or aggressive working of the action can trigger a false reading. However these are easy to identify in your data, because the speed value is way lower than true fired shot values. Simply remove that low entry or otherwise ignore it in your calculations. To be fair, this “bump activation” really doesn’t happen very often once you get used to using the inertial trigger.
SUMMARY — Outstanding Accessory for LabRadar Users
Bottom line — if you own a LabRadar, then definitely get a JKL Inertial Trigger. Priced at just $35.00 this device is not expensive, yet it’s one of the most effective accessories you can buy for the LabRadar. I’ve recommended these inertial triggers to dozens of shooters. Every one of those guys who did buy a JKL trigger says they can’t imagine using a LabRadar without one. If you love what the LabRadar can do, but have been frustrated with shots not getting recorded 100% of the time, then definitely get yourself a JKL Inertial Trigger. It turns a good system into an amazing system. JKL Industries states that its inertial trigger “will work on anything from a .22 LR to a suppressed system or with standard rifle and brake.”
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To optimize your loads and to generate precise ballistics tables, you need a quality chronograph. Having precise readings of bullet muzzle velocities lets you calculate ES and SD to determine the most repeatable load with least vertical dispersion. Very accurate velocity data is also essential to created a precise drop table for long range and to predict the effect of winds. There are many good chronographs on the market, ranging in price from around $100 to $1000, not counting tripods.
Today’s Saturday Movie showcase features a variety of modern chronographs. We include comparison tests, as well as video reviews of the new, small-format Bulletseeker Mach 4 and AndiScan Micro A2 Doppler Radar chronographs. If you are in the market for a new chronograph and have the resources, you should definitely consider one of these new small chronos, which are easy to set-up and can be mounted directly to your rifle. For those with a limited budget, MagnetoSpeeds still offer great performance for the price. However, you may have to conduct load tuning separately with the MagnetoSpeed removed.
Triple Chronograph Comparison Test
LabRadar, MagnetoSpeed, and Shooting Chrony Alpha Master
This video has an interesting comparison test with three chronograph devices operating at the same time. A Shooting Chrony Alpha Master unit was set up downrange, while a modern LabRadar was placed to the right side of the rifle. On the barrel of the rifle a MagnetoSpeed chrono was attached. This allowed the tester to compare shot velocity values from all three chrono systems at the same time. The video creator explained: “I was curious to see if my old [Shooting Chrony] chronograph could still give me useful velocity information compared to using the newer MagnetoSpeed and LabRadar.”
Chronograph Functions and Features — Vortex Nation Podcast
In this 78-minute video, experts from Vortex explaining how modern chronographs work. The discussion covers the technical features of various chronographs. Multi-time F-Class National Champion Ian Klemm and former sniper Tony Palzkill examine different chronograph types, explaining how they operate. Ian discusses the pros and cons of different chronograph designs, and provides many good tips for chronograph owners. This 78-minute discussion covers multiple chronograph designs, including LabRadar, MagnetoSpeed, and Caldwell Ballistic Precision. There is also extensive discussion of ballistics in the first 20 minutes.
MagnetoSpeed vs. Caldwell Ballistic Precision Chronograph
In this video the host compares a MagnetoSpeed with an older, first generation Caldwell Ballistic Precision Chronograph, mounted a few yards downrange on a tripod. The tester favored the Magnetospeed saying it was “incredibly accurate” while being much easier to set up and transport. He also says the MagnetoSpeed App was very “user-friendly”.
NOTE: Skip Forward to 5:40 to see the Bulletseeker field-tested as mounted on rifle and on tripods.
The Bulletseeker Mach 4 is a new radar chronograph that mounts directly to your rifle. The advanced Bulletseeker features 120 Ghz radar with a beam-forming lens. Developed in Europe, with made-in-Germany core components, this unit is sold in the USA for $999.00 by Longshot, trusted maker of long-range target cameras. We think this is a game-changer. You get advanced radar ON YOUR GUN, with no need to haul around a bulky LabRadar.
Comparison test with the Bulletseeker Mach 4 and LabRadar
Another Bulletseeker tester was very impressed: “Based on my experiences with the device it seems like a good product that does everything it advertises. All the benefits of a LabRadar without the drawbacks.” (SEE Product review HERE.)
In this video, our friend F-Class John tests the innovative, ultra-compact AndiScan Micro A2 Doppler radar chronograph. This unit is small enough that it can be fitted to your rifle, or attached to a front rest or mini tripod. John tested an early pre-production model. The production model is now available for 800 Euros on the SQI-AndiX eShop. The manufacturer notes: “The next large 2023 production series is expected to be ready by the end of February.”
Product Description: “The AndiScan Micro A2 is an advanced ballistic velocity Doppler radar for measuring muzzle velocity of projectiles. It operates in 24GHz frequency band. It is a highly integrated and extremely small form-factor device that is intended to be directly mounted on the rifle. This frees the user from a complicated setup alignment and it also allows to perform measurements under dynamic conditions. It is the first device [with] this form-factor on the public market.”
JKL Inertial Trigger for LabRadar
The JKL Inertial Trigger for the LabRadar is an easy-to-use, inertial-driven trigger that activates simply from the recoil of your gun. Rather than activate by sound or Doppler reading, the JKL Trigger works from the rifle’s instantaneous recoil pulse when a shot is fired. The unit consists of a small rectangular pad attached to a long audio cable. All you do is plug in the audio cable, attach the pad to your gun with the provided hook and loop (Velcro) material. Then (important), you must change the LabRadar trigger settings from “Doppler” to “Trigger”. The unit works great and is easy to set up.
The text in this article is Copyright 2023 AccurateShooter.com. No site shall reproduce this article without express authorization.
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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 some years ago, 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.
Barrel Velocity Variance
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).
IMPORTANT: 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, 6mmBR, .243 Win, 6.5×47 Lapua, 6.5 Creedmoor, 6.5×55, .308 Win, 30-06, or .338 LM 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. [Editor’s NOTE: The original test was conducted in 2008. The velocity of current-production Lapua factory ammo might be higher or lower, so your results may vary.]
When you complete a new 6mmBR rifle, it’s definitely smart 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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Why You CANNOT Rely on the MV Printed on the Ammo Box!
When figuring out your come-ups with a ballistics solver or drop chart it’s “mission critical” to have an accurate muzzle velocity (MV). When shooting factory ammo, it’s tempting to use the manufacturer-provided MV which may be printed on the package. That’s not such a great idea says Bryan Litz of Applied Ballistics. Don’t rely on the MV on the box, Bryan advises — you should take out your chrono and run your own velocity tests. There are a number of reasons why the MV values on ammo packaging may be inaccurate. Below is a discussion of factory ammo MV from the Applied Ballistics Facebook Page.
Five Reasons You Cannot Trust the Velocity on a Box of Ammo:
1. You have no idea about the rifle used for the MV test.
2. You have no idea what atmospheric conditions were during testing, and yes it matters a lot.
3. You have no idea of the SD for the factory ammo, and how the manufacturer derived the MV from that SD. (Marketing plays a role here).
4. You have no idea of the precision and quality of chronograph(s) used for velocity testing.
5. You have no idea if the manufacturer used the raw velocity, or back-calculated the MV. The BC used to back track that data is also unknown.
1. The factory test rifle and your rifle are not the same. Aside from having a different chamber, and possibly barrel length some other things are important too like the barrel twist rate, and how much wear was in the barrel. Was it just recently cleaned, has it ever been cleaned? You simply don’t know anything about the rifle used in testing.
2. Temperature and Humidity conditions may be quite different (than during testing). Temperature has a physical effect on powder, which changes how it burns. Couple this with the fact that different powders can vary in temp-stability quite a bit. You just don’t know what the conditions at the time of testing were. Also a lot of factory ammunition is loaded with powder that is meter friendly. Meter friendly can often times be ball powder, which is less temperature stable than stick powder often times.
3. The ammo’s Standard Deviation (SD) is unknown. You will often notice that while MV is often listed on ammo packages, Standard Deviation (normally) is not. It is not uncommon for factory ammunition to have an SD of 18 or higher. Sometimes as high as 40+. As such is the nature of metering powder. With marketing in mind, did they pick the high, low, or average end of the SD? We really don’t know. You won’t either until you test it for yourself. For hand-loaded ammo, to be considered around 10 fps or less. Having a high SD is often the nature of metered powder and factory loads. The image below is from Modern Advancements in Long Range Shooting: Volume II.
4. You don’t know how MV was measured. What chronograph system did the manufacturer use, and how did they back track to a muzzle velocity? A chronograph does not measure true velocity at the muzzle; it simply measures velocity at the location it is sitting. So you need to back-calculate the distance from the chrono to the end of the barrel. This calculation requires a semi-accurate BC. So whose BC was used to back track to the muzzle or did the manufacturer even do that? Did they simply print the numbers displayed by the chronograph? What kind of chronograph setup did they use? We know from our Lab Testing that not all chronographs are created equal. Without knowing what chronograph was used, you have no idea the quality of the measurement. See: Applied Ballistics Chronograph Chapter Excerpt.
5. The MV data may not be current. Does the manufacturer update that data for every lot? Or is it the same data from years ago? Some manufacturers rarely if ever re-test and update information. Some update it every lot (ABM Ammo is actually tested every single lot for 1% consistency). Without knowing this information, you could be using data for years ago.
CONCLUSION: Never use the printed MV off a box of ammo as anything more than a starting point, there are too many factors to account for. You must always either test for the MV with a chronograph, or use carefully obtained, live fire data. When you are using a Ballistic Solver such as the AB Apps or Devices integrated with AB, you need to know the MV to an accuracy down to 5 fps. The more reliable the MV number, the better your ballistics solutions.
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If you have been waiting to purchase a chronograph… now is a great time to buy. You can get the affordable MagnetoSpeed Sporter for under $180.00. You can set up this device in a few minutes. Just mount the unit to the end of your barrel with a strap. 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.
See MagnetoSpeed Sporter Chronograph Features Reviewed in Video
We’re impressed by the Sporter chrono, as are other shooters — this unit is very popular. Like the MagnetoSpeed 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 Adapter (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 $179.00 at Brownells and $179.00 at Amazon.
The Magnetospeed Sporter 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.
Q: Will the Sporter Chrono work with thicker barrel (i.e. greater than 1″ diameter)?
A: The manufacturer recommends the more upgraded V3 model, $380.00 on Amazon 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. The video below covers the Sporter’s features and operation.
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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 at top, the problem is obvious — he ventilated his Chrono.
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.
Other Forum members offered some sarcastic responses:
Try it on an overcast day – it might work again.
It looks like the V-Max performed just about as advertised.
Aww…a little duct tape and some Super Glue and you’re good to go.
Double Check Your Aim Point and Trajectory BEFORE You Shoot
The lesson learned here is that you should never change targets (or aim points) without checking your bullet’s flight over the chronograph. We like to align the barrel so the bullet exits a good 6-8 inches above the electronics (check your manual for recommended shot height). In addition, we always boresight the barrel so we can see the actual target through the bore. Then, with gun UNLOADED, bolt removed and action clear, we look back down the barrel so we can see daylight through the bore, with the gun set on solid rests. If you look through the middle of the “V” formed by the sky screen supports and you can’t see light shining through the barrel’s bore, you probably have a set-up problem and you should re-align the rifle.
Use a Test Backer to Confirm Your Bullet Trajectory
You can put tape on the support rods about 6″ up from the unit. This helps you judge the correct vertical height when setting up your rifle on the bags. Another trick is to hang a sheet of paper from the rear skyscreen and then use a laser boresighter to shine a dot on the paper (with the gun planted steady front and rear). This should give you a good idea (within an inch or so) of the bullet’s actual flight path through the “V” over the light sensors. Of course, when using a laser, never look directly at the laser! Instead shine the laser away from you and see where it appears on the paper.
After you have used the laser boresighter to get the rifle centered up in the chrono’s “sweet spot”, confirm with a test shot or two (see photo). Even when using an in-chamber laser boresighter, it is not uncommon for the bullet’s actual point of impact to be different than the laser’s dot location.
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Barrel Velocity Variance
