Detailed Comparison of the LabRadar, MagnetoSpeed, and Two-Box chronographs

Discussion in 'Reloading Forum (All Calibers)' started by Ammolytics, Sep 6, 2019.

  1. Ammolytics

    Ammolytics

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    Going into this, I didn't think it was going to be enough and wanted to use more chronographs, rifles, and ammo. Now that I've done it and it took me a month just to process all the data and write the article, I know that I was already in over my head.

    Since they haven't changed much since he wrote it, there's a much more rigorous comparison of optical chronographs in Bryan Litz's book, which I link to in my article. He did use a first-gen MagnetoSpeed, but the LabRadar and Two-Box chrono weren't on the market yet. I'm not sure that I could have added much more to his comparison.

    I'm also looking forward to seeing how the LabRadar matures. Although if you saw my work on the Open Trickler, you can understand why I'm intrigued by this little gadget.

    https://groupgets.com/campaigns/586-a111-breakout-board
     
  2. SGK

    SGK Silver $$ Contributor

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    What have you actually compared? Is the variance in shot to shot velocity readings coming from the rifle and the ammo or is it the inherent measurement error of the chrono? All your numbers are rather meaningless I'm afraid.

    The Two Box isn't great for absolute velocity measurement. It requires very careful setup to get that right. But it wasn't built for that purpose. Where the Two Box excels is in its extremely low inherent measurement error SD. It was built for load development and someone wanting to measure velocity SD and not someone wanting to measure absolute average velocity. In that context, setup couldn't be easier - just plonk the boxes down and start shooting. It takes about 20 seconds to set up.
     
    Last edited: Sep 8, 2019
  3. Ammolytics

    Ammolytics

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    Hey, thanks for sharing your feedback!

    The question you've asked doesn't leave me with the impression that you've read the article? In particular, you may want to re-read the "How I Compared" section, in which I detail my goals and describe the challenges of comparing chronographs. Further, in the Disclaimers, I make it clear that this was not a focus on my firearms/ammo and can only really apply to the specific units that I tested. All of these should sufficiently answer this question for you, but I'd love to know if I could clarify anything!

    Regarding the Two-Box: If this isn't its purpose, then I'd argue that its goals/non-goals should be made much more clear on the website/marketing material. If you're questioning how I set it up, I described in the article just how careful I was (even using bubble levels). Perhaps this will be more clear in the YouTube video, since I did record myself setting it up.

    The only way to really know whether any model/brand chronograph is accurate or precise is to use different kinds at the same time -- that's exactly what I did and I still believe that it can be beneficial for everyone to learn from my approach and results.

    Either way, I'm sorry if you didn't find this useful. I'd love to hear your thoughts on how I could do it better next time!
     
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  4. jthor

    jthor

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    Looks like the LabRadar and Magnetospeed are pretty consistent and close to each other while the Two Box Chrono is inconsistent and off much further than the other 2 chronos.
     
  5. SGK

    SGK Silver $$ Contributor

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    I read it. More than once. Like I said, your numbers and statistics are meaningless and you simply can't draw any conclusions from them. (The problem with your penultimate comment above in post 23 and is that you don't know which of the three was more accurate. You recognize this in the article but then proceed and attempt to draw conclusions, or let others do so, even when you know the analysis is deeply flawed.) To do it better you need a known-good reference measurement - and implementing that sort of test is very hard to do.

    Regarding usability, your comments are fair except to say that if you have a chronograph which picks up neighboring shots (i.e. accepting that for the moment) having the ability to download the data is rather pointless - your data dump includes a lot of samples that need to be deleted. For practical use and load development the ability to download to an excel spreadsheet simply isn't necessary. You have relatively small sample sizes and it is very easy to shoot and then note the velocity with pen and paper. Keying these into Adam's online calculator https://www.autotrickler.com/stats-calculator.html avoids the need for constructing a spreadsheet and knowing the formulae for all the statistics. More importantly, confidence interval analysis and determining whether two sample sets are meaningfully different is much more powerful for load development than just knowing the simple average and SD/ES. Understanding the maths behind this and even inputting such formulae into a spreadsheet would stretch a lot of people. Magnetospeed and, I believe, LabRadar don't incorporate such analysis tools into their products.

    Of course, having a chrono that doesn't pick up neighboring shots is advantageous but practical use of the Two Box isn't difficult or annoying. With regard to positioning/setting it up, if you even care about this, I think you will find having the sensor boxes at the same height is much more important than having the boxes sitting level. So the bubble levels likely don't add much if anything at all.

    PS I have both the Magnetospeed and the Two Box. I don't use the Magnetospeed anymore. If I want to compare the SD/ES of strings of fire I shoot over the Two Box with a "just plonk it down" set up. Its measurement of variance (SD) isn't clouded by as much inherent measurement error and I don't care about the absolute figures per se. For absolute average velocity measurements, for computing (rough) expected trajectory for example, I just use my ShotMarker.
     
  6. hogpatrol

    hogpatrol Don't criticize the farmer with your mouth full. Gold $$ Contributor

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    No good deed goes unpunished.
     
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  7. F Class John

    F Class John NRA Life Member Gold $$ Contributor

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    I think he actually states in his report that he feels the two-box while not necessarily as accurate was probably the most ‘precise’. This supports views above regarding its efficacy for load development however may not lend itself as well to disciplines that require more ‘accurate’ numbers for distance calculations. Ain’t nobody gonna ever agree on a stupid chrono in my opinion. I’ve owned all three, I love my MS for what I do and others love their respective ones for what they do. I get picked on for having an MS, I see others catch flack for owning something different. Sadly it’s what happens when people get invested in technology (apple vs android??). It’s all about finding the tools that help you accomplish you goal and while inconclusive (like nearly every other chrono comparison I’ve seen) it does help give some notions as to how and why one could be better for someone than another and in that sense I think it accomplishes it goals.
     
  8. dmoran

    dmoran Donovan Moran Silver $$ Contributor

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    @SGK
    I found all Eric's data in his report to be very relevant, and appropriate to such a report.
    One of the best reports I've ever read on the topic.

    Your obvious bias to the 2 Box Chronograph, has turned into rant (the way I see it).
    Appears to me you just don't get it, or your just being a troll, or both.

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    Eric,
    Hope this guys bias rant, doesn't detour you to bad.
    But is a good example of why many don't share much here any more.

    Again... Great Report .... and Thanks for sharing
     
    Last edited: Sep 9, 2019
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  9. Ammolytics

    Ammolytics

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    The best-case scenario is to compare against a known-good reference -- I agree! However, it also useful (though not as rigorous) to compare each device's measurements to the mean of all devices used. (Bryan Litz says as much in his book, which I linked to in the article).

    Unfortunately, I don't personally have access to the laboratory-like facility which would support such an endeavor, nor the budget for that matter. I knew that going in, which is why I set different goals for myself. As with all of my work, I'm much more interested in the truth than being right or wrong. If I make a mistake, or could do things better, I'm happy to accept constructive criticism so that I can learn from it and improve!



    There's a lot in here to unpack, so I'll try to be concise and enumerate each of your pieces of feedback.
    1) As I wrote, everyone has different use-cases, so the "practicality" of it's usage is highly dependent on the type of range/environment folks have access too. It's subjective.
    2) My point about being able to download the data was one of time-management and also goes along with the previous point, since it may not always be practical for the user to write down every reading the Two-Box displays. If a device records data and gives it to you without having to write it down or type it in manually, then it will save you time (and prevent possible typos).
    3) One thing I did not write was that the screen glare was bad enough during this experiment that I may not have been able to do that anyway.
    4) I agree that the simple statistics that folks commonly use are not the best indicators, and that spreadsheets kind of suck! I am working on a separate article which focuses purely on statistics, which will cover this much more thoroughly and will be sure to glaze over many eyes.


    I had written about a previous experience with the Two-Box where we used it at a busy 600-yard line. We weren't super careful with how we set it up (just plopped it down basically, like you had suggested earlier) -- the sensor boxes were clearly tilted, which we suspected had lead to them picking up neighboring shots. That's why I decided to be much more careful this time, even to use bubble levels to avoid any potential sources of error. It may not be necessary, but it also shouldn't hurt.

    You raise an interesting point though -- were my boxes at the same height? I'm not sure I have a good way to measure that, honestly. Here's a photo snapped from the video where I was getting it lined up, so you can see for yourself. Obviously, the camera doesn't show the same angle as my eyes. Anyway, getting the same height actually seems like kind of a hard problem to solve -- you don't have a ton of wiggle room when shooting prone and no real way to measure their relative height.

    It would be nice to see a solid-mount system for the Two-Box, like a rail, to make it a bit easier to align.

    Screen Shot 2019-09-07 at 10.39.45 PM.png


    Hey, if the Two-Box works for you -- that's great! We're fortunate enough to get to use the ShotMarker every week during 600-yard F-Class practice. I really like that they provide velocity data, though I have not seen it's error rate published, so I'm not sure what variance to expect.

    Anyway, it seems like you have some strong opinions about this and that's fine -- it's fine to disagree!
     
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  10. PatMiles

    PatMiles Gold $$ Contributor

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    I have to wonder HOW LONG the rail would have to be? What would be optimum, 2 feet, 6 feet, 10 feet, 15 feet? I would guess that 15 feet would be best but that's a long rail.
     
  11. F Class John

    F Class John NRA Life Member Gold $$ Contributor

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    Yes it would. When I had mine I played with a telescoping pole both for alignment but also so I could set it up or take it down while behind the firing line.
     
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  12. PatMiles

    PatMiles Gold $$ Contributor

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    That is one helluva routine to go through to set up a chrono.
     
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  13. wkdickinson

    wkdickinson Gold $$ Contributor

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    Ammolytics, I also want to commend you for sharing your work. I found it very enlightening. I never thought your purpose was to prove which system was the most accurate, but rather to compare measurements of the 3 systems for the same shot. I believe you accomplished that and wrote a great report detailing your findings (with all the "weasle" words appropriately noted).

    I find it appalling that people feel the need to belittle other's work, ideas or questions, particularly on this forum. It seems the majority here are part of the greater collective, trying to increase the overall knowledge base. I am a long time shooter, reloader and competitor and while I don't necessarily agree with everything I read here, I would never "attack" the contibutor, which happens way to often here. I can see why people are reluctant to offer information or ask questions (I am personally very hesitant to ask a question anymore, after experiencing several such responses).

    Seriously, if you disagree with someone, at least be civil in your critism, or just don't say anything at all and go on about doing things the way you KNOW they should be done! The rest of us less knowledgable will glean what we can and hopefully do better.

    FYI - I have anew Magneto Speed V3
     
    Last edited: Sep 9, 2019
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  14. SGK

    SGK Silver $$ Contributor

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    @dmoran It's not a rant at all. I read the report looking for useful info on the LabRadar, the one of the three (actually four if you count the ShotMarker) I don't have. If you don't understand that the statistics presented don't have any practical value I can't help you.

    @F Class John you can't conclude from the lower SD of the sample observations from the Two Box yielded that it has lower measurement error either. It could have underestimated the actual SD with greater measurement variance error.

    The point is, the analysis - while well intended - falls victim to the exact caveats presented. And so producing the data and trying to draw conclusions from it is misleading. Without a known good reference point you can't tell whether one or another is under or over measuring absolute velocity, SD or anything else. Unfortunately, you can't tell anything from the numbers. Doing the right analysis is very, very hard and, as Ammolytics notes, requires some expensive kit.

    (For 'accurate' absolute velocity measurement with the Two Box both sensors need to aligned with bullet path - in both planes. Chasing that sort of setup is likely an unrewarding endeavour. Just use it for what it was designed for: ES/SD sampling. If you want your chrono for bullet drop estimation - something that should always be validated by actual shots at range anyway - don't buy the Two Box.)

    FWIW Ammolytics your commentary on setting up the LabRadar was appreciated. You might want to read Adam's blog statistics series ahead of writing your article on same.

    Anyway, you guys are taking my comments all the wrong way so I'm out. Have fun.
     
  15. Ammolytics

    Ammolytics

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    Thanks for the kind words -- I'm glad you enjoyed it!
     
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  16. jthor

    jthor

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    I have a lot more faith in the LabRadar and Magnetospeed for FPS accuracy. All tests I’ve seen of the LR and Magneto side by side has them very close to each other in FPS. This is the second comparison of the 2 with the 2 Box Chrono where the 2 Box was well off from both the LR and Magneto.
     
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  17. mchees1

    mchees1 Silver $$ Contributor

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    Surprised to hear you had problems with the Labradar. I have a Labradar that I bought when they first came out and have never had any type of problems. I found the Labradar people absolutely great to work with when I did have questions. Did you try to work with Brownell's or did you contact the Labradar people? Once you understand the settings, the size and shape of the radar cone, and how to set up and aim the unit correctly, it works perfectly. I shoot 20 Vartarg up to .338 Norma Mag and all track without any problems. I can't imagine trying to develop loads without my Labradar. Way better and easier than my CED M2 and my Magnetospeed - both of which I have sold. Takes me about 2 minutes to mount it to my tripod, aim it, verify settings, and shoot. Hope you get to enjoy the benefits of the Labradar in the future.
     
  18. JimSC

    JimSC

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    First problem was the bluetooth. It would not connect to my Samsung tablet, Samsung phone or daughters Iphone. I called Labradar but it was a Friday afternoon and the guy sounded like he wanted to get off the phone and out of the office as quickly as possible. The CS amounted to the Labradar is working as designed it is your devices that won't connect, have a nice weekend and goodbye. I did some emails to them also but it eventually came down to the bluetooth ain't gonna work so suck it up or return it to Brownells. I really wanted this thing to work however and resigned myself to no remote control and I took it back to the range again. That's when I found out I needed to buy a microphone adapter for .22 LR. Even with a aiming tube rigged on it it was a pain to focus and would miss at least one or two shots every couple of groups. Sucks when shooting for SD's. The last straw was when the USB port that you connect the external battery up with went out. As others have pointed out this thing eats batteries if you forget to disarm it except when actually shooting . I am sure Brownells would have replaced it instead of giving me a refund but quite frankly I was fed up by that time. There is a thread on here I started seeking help from other owners here but I think I have most of the details correct.

    The reason I had bought it was that my old Pro Crono had a internal rattle after eight years of being bounced around in a jeep wrangler and died a tragic death when it got knocked off a bench and fell 4 ft onto a concrete apron. Other guys had the Labradar and most had give good reviews and one helped me set mine up the first time I used it. Even he had a hard time getting it to pickup shots reliably so it may have been a bad unit straight from the box.

    Anyway after getting my money back from Brownells I ordered a replacement Pro Chrono for 110 bucks. I use the optional Digital Link which always hooks up to any of my phones or tablets without fail. It gives me better data and more options on what data than the Labradar software did and I can import that data straight into Office with no SD card required. The accuracy of the Pro Chrono is very acceptable. Last week I shot 5 shots while zeroing a new scope at 100. I took the avg velocity plugged it into a ballistics calculator and rang a 1 MOA gong at 300 on the first shot. It works with everything I shoot with no adapters needed unless I want to go indoors , which I don't. I set it up using a laser boresighter to align it and a 15 foot piece of rope for consistent distance from the bench. Takes five minutes and missed shots are rare. Batteries last forever

    I think the Labradar unit I received may have been a lemon. But my initial experience with them was not good. I may buy a Labradar V2 if one ever comes out. But at the moment between the software, the PITA setup, the battery life, the CS, and the cost I was never so unhappy with a purchase. As of now I am perfectly happy with the ProChrono and Digital Link. As far as my technical ability I was a Navy nuke and after retirement I did commercial and industrial refrigeration. I have just a tad of tech savvy

    edit - I wonder why the people that made this thing did put the magnetron and main electronics in one cabinet and the antennae and microphone in a smaller unit that could sit in front of a rest or bipod. Seems to me that solve a lot of problems. I set my bench, flags, spotting scope etc in a certain way whether in practice or match so having that 12 inch orange square blocking whichever side of my shooting lane sucked. They also need better data readout on the unit as well as improved software for data output, maybe some LED lights to let you know when it is armed it would be more user friendly. If they could do all that for ver 2.0 I might even buy one for bragging purposes. Best thing about technology is it always gets better and cheaper. This is just the first generation of these things
     
    Last edited: Sep 10, 2019
  19. David101

    David101

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    I have done comparisons of my Magnetospeed against a lab radar and the Original Gold Standard the Oehler with the proof channel and maximum distance. The results while not all the same absolute number all tracked the same with the same offsets between them. The absolute number was not a big difference and could be attributed to the distance from the muzzle ect.
     
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  20. tonyben

    tonyben

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    Hey, I recognize that range! I love my Labradar. Good write-up! I've

    I need to play with my LabRadar more but so far, it's leaps and bounds better than my old CED M2 chronograph and less of a hassle.

    I recommend using junk ammo to setup the Labradar before testing a string to make sure you've got the position set up correctly for the rifle you're about to do load testing on. Once the position and sensitivity is verified, then it should be smooth sailing.

    I like the fact that, especially at TCGC, I can setup the Labradar on a hot range and there's no downrange setup. I also like the fact that I don't have to clamp anything to my rifle. I'm testing a short barreled M14 and there's no way I can mount a Magnetospeed to it.
    [​IMG]

    I just use a tripod on the left side of the bench and run with it.
    (one of my guests shooting a GA Precision)
    [​IMG]

    That was my first day using the Labradar.

    I really need to join you guys at the 600 yard shoots more often. I've got a co-worker who wants me to introduce him to long range shooting.

    Tony.
     
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