Thanks Bro. Got it ordered.
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LABRADAR PROS AND CONS
- Thread starter Bill Norris
- Start date
Thanks Bro. Got it ordered.
MikeMcCasland
Team Texas F-T/R
I've now run mine twice off the inertia trigger while I had an MS V3 attached.
First time I did it was when the LR was new to 'check it's accuracy'. It was within ~5 FPS. In the initial testing, I was convinced it was dead on.
Second time I did it was a month or two after owning it. I was getting numbers with the LR that I didn't believe... 30-50fps velocity swings in minor temp changes using H4350. I put the MS V3 on it and shot a string, and the shots were within ~1-5FPS for all 20 of them.
So far as I'm concerned, the LR is accurate with the inertia trigger.
On a related note, you see some interesting things chronographing every round. Changed the way I viewed certain powders/primers/bullets.
Ledd Slinger
Silver $$ Contributor
If you want to go deeper down the rabbit hole...
There has been some discussions about certain powders that are normally considered temp stable in most cartridges now exhibiting temperature sensitivity in certain case designs. It would seem that in some instances, case dimensions "might" change the characteristics of a powder with how it reacts to temp changes.
However, I am uncertain if there were other atmospheric conditions other than temperature taking effect. H3450 is normally considered a temp stable powder. I am curious which cartridge you experienced this with and whether or not all other atmospheric conditions were the same besides the slight temp difference? Humidity, barometric pressure, etc... Maybe the position of the moon and its level of gravitational pull on the earth?
Lol.But seriously, I am curious because I have also experienced some crazy speed changes in slight temp swings with powders that did not exhibit the same characteristic in other cartridges/rifles.
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Dusty Stevens
Shiner
My 10,000ah lasts for weeks
@powderbrake where did you get the eye protector bit? Very sensible.
Dusty Stevens
Shiner
1/4” tubing laid in the notch
nmkid
Gold $$ Contributor
Lowe's tomorrow morning.
PatMiles
Silver $$ Contributor
arkcomatt
Matt Owens
I bought one from mkmachining.com. Works great and Lr will still fit in the carry case with an arkcomachine.com base.
Couldn't help it. My base and their sight work. Great combination.
nmkid
Gold $$ Contributor
Thanks. Just ordered one.
nmkid
Gold $$ Contributor
So, knowing nothing about these chargers...Do you just buy the one that provides the highest mAh?
PatMiles
Silver $$ Contributor
You can probably go about as big as you want but then you'll end up with a Die Hard from Sears.
The 20,000mAh battery will last you a loooong time before you have to charge it. No worries about arriving at the range and finding that the batteries in your LR are tango uniform and your load development is not gonna happen.
You won't be sorry.
powderbrake
Gold $$ Contributor
I never responded to this. I was hoping to get a response from LabRadar before doing so.
The manufacturer claims it "has an accuracy of 0.1%" (From their FAQ.) However they don't explain what this number is, what statistic it represents, let alone the test conditions under which it was determined. Does it mean that every shot's recorded speed will be accurate to within +/- 0.1%? Think of that as the ES of error. That would be great assuming a high enough number of samples in their test to provide great confidence (interval), none of which we know. Is 0.1% the standard deviation of error? An error SD of 3 fps, versus an average of 3000 fps, would be relatively average even with a high sample count. Or is it another statistic called "Standard Error"?
Standard Error is used to describe the mean of a sample set. That's a very different statistic from the random error of the measurement device. Focused on SD in your load development etc? That's the random variance of your load and the random error of your measurement device combined (on a RMS basis). The latter is not Standard Error.
https://www.radford.edu/~biol-web/stats/standarderrorcalc.pdf
(You can derive SD from Standard Error if you know the number of samples. SD = SE x SQRT(N). If a sample size of 25 (quite low) produced a Standard Error of 3 fps vs an average of 3000 fps then the SD is a whopping 15 fps. That would be p*ss poor.)
So basically the problem is that without more information we have little idea about how 'accurate' or 'precise' the device is. The average velocity of a bunch of shots has only limited value, even if it is accurate. (Most people only think of this average when thinking about device accuracy.) If you look for velocity flat spots in group ladder tests (shot in the same session/setup) it's helpful. The absolute figure provides a starting guide for extrapolating trajectory/drop at further distances, but you'd want to confirm these on paper anyway. It doesn't help at all if you are focused on variance. Here you'd like to know that the measurement device is very precise (has low measurement error) and care less about the absolute number.
Maybe someone got more information from LabRadar or other sources.
Ned Ludd
Silver $$ Contributor
Regardless of the precision/accuracy of any chronograph made, the small sample numbers (n) we use for typical load development usually mean that there is not a whole lot of statistical weight behind the findings. Most of the chronographs I've ever used listed the accuracy of measurement to a percent value. Whether correct or not, I believe most of them simply mean "MV =/- some percent of MV when they use that terminology, because an SD or SE value would not normally be expressed as a percentage. FWIW - the LabRadar value of 0.1% among the lower values among manufacturers that actually provide such information. Given other variables that go into the equation such as properly setting up/aiming any chronograph device, the typically small shot sample number (n), etc., I think there is a limit to what we can and can't say from most typical chronograph data. Nonetheless, shooters use chronographs because they work, and they allow for load analysis in a way that is better than it would be without them.
Agreed on this part. And not many understand confidence intervals and just how they're affected by N, and hence how little (statistical) confidence they can have in 3-5 shot strings.
I've been chewing on getting a LabRadar for awhile now. I just hate it when a manufacturer tosses out a technical specification that is utterly meaningless. Currently I use the Two Box Chrono. I have confidence in its inherent precision (very low random error SD) because I've studied the dataset Adam put up on his website. It's accuracy (how well it measures absolute velocity) is very setup-dependent (likely much more so than LabRadar); so much so that I simply don't fuss with setup and rely on it for SD only. It has a few other constraints (forward of firing point, picks up a LOT of other shots on a busy range etc) but these are generally manageable plus it's damn cheap. It does what it was designed for extremely well. I rely on my Shotmarker for average velocity (and back calc muzzle velocity). That said I like toys and it would be nice to see the LabRadar provide both good precision and accuracy.
I called LabRadar and asked them the question about their accuracy statement. I didn't expect the guy who answered the phone to know the answer but sure hope he goes and gets it. Politely he took down my email address and said he would respond. I hope he does. We shall see.
Ned Ludd
Silver $$ Contributor
I seem to recall asking someone at LabRadar the same question some time ago. I don't actually remember what the specific answer was, but I do seem to recall he at least gave me an answer. Hopefully, the LabRadar folks will address your inquiry in a satisfactory manner.
In some cases, manufacturers provide performance analysis results for their equipment in very nebulous terms when they really don't want too much attention given to any specific measure of accuracy/precision. A very good example is analytical balances. Inexpensive analytical balances of questionable reliability often provide calibration figures in such a way it is very difficult to determine exactly what they mean. In contrast, high end analytical balance manufacturers such as Mettler, Sartorious, OHaus, etc., actually provide calibration data far beyond what most users would ever need or even understand in most cases. In other words, they must really want the users to know how good their products are. With the various chronographs I've owned, I don't recall ever seeing a velocity measurement accuracy number that wasn't simply a percent. If you get a good explanation of what that value really is, please share it with the rest of us here.
As far as accuracy and precision, in the last few years, I have used both a MagnetoSpeed and more recently, the LabRadar. In terms of direct comparisons using both chronographs, the precision was equally good as far as I could tell. All variations within any single velocity data set were faithfully reproduced by both units. However, the LabRadar consistently returned a value slightly below that of the MagnetoSpeed (lower, but within ~10 fps, or less). The difference between the two units was small enough that it didn't make a noticeable difference in terms of bullet drop at 600 to 100 yd. In terms of "accuracy", I have had very good results from either unit in terms of using the established velocity numbers along with BC and atmospherics to predict drop at various distances out to 1000 yd. However, my readout for that is often based on comparing where my elevation turret ends up in order to center a shot string in F-Class competition at some set distance to my known 100 yd zero, which is not necessarily the most accurate way to do it. Nonetheless, it represents one "real world" use for chronograph data. In actuality, I am often surprised how close to the target center I can put shots with loads I have never fired at distances over 100 yd, so presumably the velocity data can't too far off. I still hesitate to read too much into though, simply due to my sample size typically being only 4 or 5 shots.
I have been a big fan of the MagnetoSpeed since it was first released. It is very reliable and fairly simple to use. However, it's weakness is that it affects barrel harmonics and can interfere with the load development process. The advantages of the LabRadar are that it doesn't affect barrel harmonics. That is a big deal for me...no more loading double the number of test rounds to shoot the same load with the MagnetoSpeed for velocity, and without, for grouping. The LabRadar certainly has a few quirks/issues, such as picking up shots from neighboring shooters. But all in all, I find it to be a step up from the MagnetoSpeed in term of convenience and usefulness.
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