Preliminary LabRadar Testing

[Bryan Litz Ballistics]

I got some very preliminary results from the labradar today.

There will be more extensive reporting to follow, for now I'd like to focus on accuracy and precision.

To test the accuracy of an unknown chronograph, I place it inline with my Oehler mounted indoors on a 12' spacing with artificial lighting. My 4' Oehler, which I put downrange for BC measurements sits inside the 12' box on center, so it can be verified that the two are reading the same. These two chronos were fired over and the difference was between 0 and -2 fps. The Labradar was compared to these readings.

A couple concerns I had about this testing configuration was that my Oehlers and light boxes might obscure the view of the labradar, since it's placed off to the side of the line of sight. I'm also shooting through a portion of indoor bay before the bullet goes outside, so I'm also concerned about possible interference with things in the building being close to the line of sight. Nevertheless, I set it up and started shooting.

Another major caveat to todays testing is that there was a light rain coming and going. That couldn't have helped anything, and I'm planning more extensive testing in better conditions. Here's what I got today under these conditions.

Once I found the correct combinations of settings, the unit started reading the 215 grain Hybrids pretty reliably (308 Win FTR Competition rifle). The Labradar corrects the MV to be actual MV at the muzzle. When I accounted for velocity decay from muzzle to the center of the Oehlers, here's what I found:
For a 10-shot string, every velocity returned from the Labradar was within +/- 2 fps from the corrected 12' Oehler measurement. The average velocity from the Labradar was -0.6 fps compared to the corrected 12' Oehler which is incredible accuracy and precision.

The SD of the Oehler data is 9.2, and the SD from the Labradar on the same 10 shots was 10.0. ES on the Oehler was 28, and it was 30 fps on the Labradar.

This is a very good result in terms of both accuracy and precision.

To further test the unit, I set up a .223 Remington to shoot 55 grain bullets. More challenging as the bullet is smaller and faster.

Results were not as good in this case. About 1/3 shots didn't read, and 1/3 produced wildly inaccurate numbers (like 2000 fps when actual is closer to 3500). 1/3 of the shots resulted in realistic numbers, but they weren't quite as good as the .308 data. For the 5 shots of 223 that I got 'good' data for, they read on average 15 fps slow compared to the corrected Oehler data, and there was more scatter in the error.

I won't dwell too much on the 223 scenario, as I believe it's a result of interference from the rain, or possibly equipment near the line of sight, or both (my guess is it's mostly rain related). So all you can take from these .223 results is that the unit isn't reliably accurate in the rain which is not a big surprise or mark against the product.

At the end of about 4 hours continuous testing, the batteries were more than 1/2 drained (according to the on-screen battery indicator). The unit is always going into screen-saver mode to save battery, but still they drain pretty quick. It's a good thing it has a battery indicator. I would advise storing a fresh set of six AA batteries with the unit in case they go dead on the range.

The SD card saved a lot of the track data, which I couldn't resist playing with to determine BC from the range/velocity data. Reverse engineering the slope of a linear fit to the range/vel data from muzzle to 40-80 yards resulted in a very close match to the bullets known BC, but I wouldn't advise using the unit for the purpose of measuring BC. The data file also stores a bunch of other data including signal to noise ratio for each shot.

Based on this first look, I would say the Labradar definitely shows promise and I'm eager to test it under better conditions. The data on the 308 was spot on but I'm a bit concerned about the high velocity small caliber scenario having a 15 fps average error but I'll try it again in clear conditions before worrying too much about it because it was most likely the rain that caused this result.

There's more info on the LabRadar testing in this Snipers Hide article: http://snipershide.scout.com/story/1535699-labradar-my-personal-radar?s=541 It talks a lot more about the use-ability of the device rather than focusing on the accuracy and precision. All good info with pics, video, etc.

-Bryan

 

[dcali]

Very cool. Did you happen to do any uncertainty analysis on the BC calculations made only from the Labradar data? In other words, an an explanation of where the pitfalls lie in relying only on that short range data, even if its fairly accurate data. That would be a great topic for the next book...

 

[Bryan Litz Ballistics]

I haven't looked at it close enough, only had a short time with the data so far.

 

[missed]

Good to hear ! I have been holding off on another chronograph waiting for this to come out.

 

[dmoran]

Capital information once again from the Litz camp. Thanks for taking the time to report !.!.!
Will be looking forward to fallow-ups.....
Donovan

 

[Berger.Fan222]

Thanks for the report. This device has tremendous possibilities. If things pan out as expected, one may be able to use the LabRadar in real time to determine whether shots that hit high are due to those specific bullets having a higher than expected muzzle velocity or BC (and vice versa for shots hitting low).

When we have a shot go high, we often suspect that the round "cooked" too long in the chamber before firing. It would be nice to have ES and SD on both MV and BC in the course of a 20 shot string and then to know whether the highest and lowest MVs and BCs were dropped points.

 

[dcali]

I'm interested in knowing if the BC, even at such a short range, can be calculated accurately and precisely enough to give us an idea of the bullet to bullet variation in BC. It seems obvious (or maybe not...) that long range is required for an accurate BC calculation, but you would think we would still be able to discern differences in the short range data from shot to shot. The question is if it will be sufficiently precise data to draw any conclusions about the consistency of a lot of bullets. If so, that would be pretty cool.

 

[Bryan Litz Ballistics]

Here's a sample of the track data; this one goes out to 150 yards, but as you can see, the data gets sparse and scattered past 60 yards.

The linear fit is to the LabRadar track, and shows -1.586 fps/yard of velocity loss. The red dots are the calculated velocity loss for this bullet, in the conditions and MV of the shot.

Granted, this is a linear fit and not a curve as in reality. Just showing a sample.

The highest quality track data appears to be up close, but the problems with up-close data are that: 1) the angle between the radar and your LOS is significant, so you're only getting a component of velocity not total velocity. 2) right out of the muzzle (first ~20 yards or so) the bullet can be dampening out launch dynamics that will not be present for the rest of it's flight. Measuring BC there would be misleading. 3) Measuring BC out of the muzzle will only give you the BC at 'high velocity', which will not be the same as the long range average. And finally 4) the engineer from Labradar specifically advises against using track data from the Labradar to measure BC.

I agree it's fun to look at, but my bet is it could get you within +/- 5% at best, which is not good enough for accurate trajectory modeling at long range. It would probably be good for shot-to-shot comparisons, but I wouldn't count on it to give you a truly accurate BC.

-Bryan

 

[Berger.Fan222]

Some of the questions I am considering are:

Is it better to have a BC inferred from LabRadar for a specific gun, load, bullet, stability, and conditions or a BC from Sierra or Applied Ballistics that was determined with a different gun, load, bullet (likely a different lot), stability and conditions?

In cases where the BC from Sierra is significantly different from the BC from Applied Ballistics, would a BC from LabRadar for a specific gun, etc. give a hint on whether Sierra's BC or Applied Ballistic's BC is more likely better to compute long range trajectories?

How useful would shot variations and lot variations inferred from LabRadar data in the first 100 yards be for diagnosing dropped points at 600-1000 yards? This seems to be the most promising application that just is not possible with other chronographs.

 

[Bryan Litz Ballistics]

For a bullet that is fired with adequate stability, there will be very little difference in the average BC thru supersonic range, based on the specific rifle. In other words, I don't think you need to measure the BC of a bullet from your specific rifle in order to have an accurate BC for the bullet. Lot variations in bullet production can have more of an effect than differences in rifles, but they're typically quite small as well.

One of the biggest problems with inconsistent BC's is the use of G1 BC's and their dramatic velocity sensitivity. If bullet brand 'X' advertises a G1 BC of 0.500 for a bullet, and I measure it over 1000 yards and report it's average BC to be 0.420, it doesn't mean that brand 'X' lied or inflated the BC; it could just mean that brand 'X' only measured the BC over 100 yards where the velocity was high, and the G1 BC really was 0.500.

So if you used the labradar to get a BC over 100 yards, you're more likely to get a number that matches brand 'X', which is an accurate measurement over high velocity at 100 yards. HOWEVER, that's not the true average effective BC over long range which is what you need for trajectory modeling.

If you use the labradar to reverse engineer a G7 BC over short range, that will be a lot better because BC's referenced to the G7 standard aren't nearly as sensitive to velocity as G1's, but there's still something to say for measuring the flight of the bullet over long range rather than extrapolating short range info.

You mention using the labradar to diagnose low shots on target and dropped points. I don't think you would be allowed to have the unit on the line during a match. Rules aside, I don't know how you could keep the unit from triggering on everyone elses shots. you might rack up a whole lot of data real fast! In a practice session it could be used as you describe though.

IMO, high and low shots come from either velocity or gun handling/bag/bipod issues. Unless you have bullets with worse than average uniformity, you're probably not seeing much vertical due to variation in BC.

-Bryan

 

[Berger.Fan222]

I think you may be right about most of your points above, but a lot of doubt has arisen since reading this article a few years ago: http://www.6mmbr.com/bulletpointer.html
It's natural to try and blame the bullets rather than our skills.

There is also a reasonable desire to know with greater confidence whether a given rifle/bullet combination is really demonstrating "adequate stability" under given conditions. Is a 1 in 7 twist adequate for the 90 grain SMK or a 1 in 10 twist adequate for a given 230 grain .308 bullet? Failing to see the expected high and uniform BCs in the first 100 yards could quickly end what might otherwise be a longer and disappointing trial of those bullets in a given rifle. Hard data is more compelling than theoretical formulas and recommendations from experts that seem to be based on the same formulas.

There seems to be some variation among clubs regarding how the F-Class rules are interpreted regarding use of electronics. As friends and I have worked to improve inferring causes of dropped points, we haven't yet had any negative feedback regarding a coach or friend behind the shooter using a Kestrel to record wind conditions or a camera to record flags for each shot for after-action analysis on dropped points. With this experience, I doubt we'd find objections to a coach of friend operating a LabRadar behind the shooter to record velocity vs. distance for each shot for after-action analysis. There does seem to be a triggering challenge to overcome, but I bet an external microphone next to the shooter would do the trick.

It would also be tempting to use a LabRadar to see what is happening with the bullets of the highest scoring shooters. I expect it would validate my hypothesis that there are no magic bullets, just shooters who read the wind better with bullets that are performing about the same as everyone else on the line. Such might motivate some to improve their skills rather than focus on their equipment.

 

[dcali]

Another interesting application could be to correlate variance in BC to variance in bullet dimensions. We could finally find out how finely to sort bullets by bearing surface, or whether to sort them at all.

All of it depends on being able to reliably detect variance in BC, which sounds like it's still in question, but it's an interesting possibility.

 

[dmoran]

Another interesting application could be to correlate variance in BC to variance in bullet dimensions. We could finally find out how finely to sort bullets by bearing surface, or whether to sort them at all.

I get the "jist" of what your desirie, and all good and cool the desire may be, the true facts in actuality have been repeatedly proven over many years already, by individual testings.
If you yourself have not not tested your own components from your own rifles and at your intended distances, how is someone else's 100yd resultants going to prove anything to your own set of unique circumstances?

Real life examples: in one Lot of bullets I had an 18% decrease in group sizes after pointing the meplate's. In another Lot of the same bullets, I had no measurable gains to group size.
And can say the same thing for Base to Ogive variance, where I've had some Lot's more effected by it then others to grouping capability.

Sorry if I sound pessimist here, but much to those scenario's can only be factually proven individually, and to each ones own unique scenario's, demands, and bullet Lot's.
Do to all the obvious variables from one persons scenario to another's, is where generalization resultants would only deem righteous to some and be totally wrong and damaging for others - or so is my experience.
Donovan

 

[dcali]

I'm not so pessimistic. You can separate out factors if you're able to measure them. It seems to me that you might see meaningful BC variations with variations in bearing surface (for example) within a lot of bullets. If you can measure both, you can see if that its true to a degree that matters.

Of course, bearing surface also impacts internal ballistics, so it's not as simple as that, but it looks like it may be possible to at least quantify the effect on external ballistics, which is something. Every little bit helps.

A simpler case would be bullet pointing. Everyone "knows" that it helps "a little" with BC, and "a little" with consistency. If you can measure individual bullet BC's, you can quantify this for each bullet type by using empirical evidence. You can make an individual decision as to whether or not it's worth your time for your bullet.

When ever I hear someone say (or say myself), "It just depends on what the rifle likes", I see an opportunity to understand something better. Because rifles don't like anything. If we can measure it, we can understand it. And the Labradar unit strikes me as a potentially significant step towards being able to measure a lot more than we used to be able to. I don't know squat about radars, but if it's possible to improve the performance of their chronograph with the next model or the model five years from now, we could see some really neat stuff come out of it.

It seems like the potential to rapidly prototype bullets is also something that could benefit from this. Make a change, CNC a bullet, fire a few rounds, and do it again. A guy could learn a lot with that capability. It doesn't sound like we're quite there with this unit, but here's to the future!

 

[bigngreen]

Could the LabRadar be triggered by the sonic crack if it's set up at 1000 yards behind a steel plate and shot ran past it?

 

[Jay Christopherson]

Could the LabRadar be triggered by the sonic crack if it's set up at 1000 yards behind a steel plate and shot ran past it?

I would bet that by the time the report catches up and supposing that it could actually trigger the unit, the bullet would be out of the detection cone at 1000 yards and more.

 

[geneo1]

I also got my Lab Radar and have tested it along side an Oehler chronograph.
The shooter was shooting his 7 mm F-Class rig.
The velocities were within 1 fps of each other, so I was happy (sold my Oehler to get the Lab Radar). It is really easy to set up and every one the line wanted to test it with there rifle. Glad I changed and would do it again, the comment I herd was that the person with the Oehler chronograph was going to order the Lab Radar when it out for sale.
The things I like:
Really easy to set up.
Works in the shade.
Light and easy to carry.
Won’t lose it because of the color.
And did I mention, really easy to set up!!

 

[dmoran]

Thanks for the report geneo1.........
Real glad to hear your initial positive review.

Personally I am real glad to see innovation come to chronographs, and advancements in other directions then optical eyed sensor types. Acoustic, magnetic, radar, etc. are in my opinion steps in the right direction for advancement.

I personally hope the LabRadar kind of puts all others to shame sort to speak, so that then the other mfgs. are forced to step it up to further advancement to compete in the market.

I have used chronographs for many years and strive for the data and will never be with out them. I have spent a lot of money on them and on my setups for them. But I desire new innovation and advancements, and will gladly take the lose to better myself with future innovation.
Donovan

 

[Bryan Litz Ballistics]

More testing today; pristine conditions this time.

In summary, I saw the same exceptional accuracy and precision compared to the 12' Oehler for .308. Error between the Labradar and 12' Oehler* was between 0 and -3 fps for 9/10 shots; one shot had a -5 fps error.
* data for 12' Oehler was corrected for velocity lost from muzzle to chrono center.

So for the 10-shot string with .308, the average MV measured by the Labradar was 2 fps slower than the Oehler, and the standard deviations were 6.6 for the Oehler and 7.6 for the Labradar.
This is the same exceptional performance that I saw with this unit in the initial test in the rain.

Now to see if the smaller 223 Remington shooting 55 grain FMJ's at ~3500 fps would work better in clear conditions.

same set up, same result. Most shots didn't read, of those that did read, most were several 100 fps slow. Only 3 out of 14 shots had results that were anywhere in the ballpark.
Thinking that my set up (with the big Oehler in front of the rifle) may be interfering with the Labradar's view, I moved the Oehler out of the way and got the same result. Most shots triggered but didn't track or gave bad numbers.
Finally, I moved completely outside to eliminate any possible interference with anything in the shooting bay. Same result. Even with wide open space, the unit just doesn't seem to be capable of tracking the .223. The behavior was exactly the same as it was in the rain.

To test something 'in-between' .308 and .223, I set up a .260 shooting 130 gr bullets. These results were similar to the .308; extreme accuracy and precision compared to the 12' Oehler. For 10 shots with the 260, the shot-to-shot variation in readings ranged from -4 to +3 fps, and there was less than 1 fps difference in the average! Outstanding performance in this case.

I was out of time after the .260, but I plan to test further to see where the unit begins to have problems between .260 and .223. Hopefully it works for 6mm. Not sure if the magnitude of the velocity is a factor or just caliber. My understanding of Doppler is that higher velocities should be 'easier' to track so it may just be a caliber limitation. We'll see; this is why we test.

Oh, and this thing definitely likes to eat batteries! After only a few shots into the testing today the unit started giving up and complaining about low batteries. It's very good that it has a battery level indicator, and lets you know when the juice is running out. Replacing with fresh batteries didn't seem to affect accuracy or precision so that's a good thing. It eats batteries, but the unit is designed well so you can manage it.

My next test will be with 6mm. Hopefully the small caliber issues can be addressed with a firmware upgrade and the problem isn't a hardware/sensor limitation.

-Bryan

 

[CJ6]

Bryan, Have you played with the different sensitivity settings to see if that will or would be an issue with the smaller caliber bullets? Just wondering how those settings may affect it.