Calculating B.C. with LabRadar. Tutorial on my method.

[entoptics]

Here's a relatively detailed description of my method for obtaining ballistic coefficient values using a LabRadar. I'm hoping that we as a community can start using a relatively standardized method to calculate B.C. and share those results. Something along the lines of the excellent Hammer Hunter load data thread.

I'm also hoping discussion can mostly avoid philosophical debates on the utility of B.C., manufacturer methods and motivations, etc, and focus on the nuts and bolts of the data gathering and processing using a LabRadar.

Perhaps with some good brainstorming, we can come up with a method that everyone who owns a LabRadar can use, so we can get some more "standardized" data out there. With that, we could begin to investigate variables like twist rate, velocity, and atmospheric conditions, and perhaps gain more insight on B.C. variability.

I also encourage anyone else with a method they use to start their own thread. Name it something easily searcheable with LabRadar and B.C. in the title though, so we can all find it and link it when searching and posting. I'm happy with my method, but no doubt others may have as good or better techniques they can share.

My method...

Tools you'll need...

1) LabRadar
2) An SD memory card installed while shooting. We want to use all the data we gather, not just the pre-programmed intervals that LR spits out (watch video for why that's a problem). A memory card is the only way to capture that on a LR.
3) Computer with Excel, Numbers, Open Office, etc. We're going to need to do a little data processing. My spreadsheet is attached below.
4) Weather monitoring tools. Kestrel, home weather meters, smart phone barometers, etc. We need reasonably accurate values for temperature, pressure, and humidity. These need to be at the shot location in real time.
5) Rifle, powder, bullets.
6) This one is the hardest to find...Primers.
7) JBM Ballistics free online calculator (their may be others, but this one works for me).

Setup

A) When programming your LabRadar, set the far velocity yardage to something MUCH greater than the unit will track.

The unit will stop tracking a few yards past whatever the furthest yardage you set. Instead, we want it to track as far as it can. I believe the maximum value you can set is 300 yards? For large diameter bullets (e.g. 44 mag, 50 BMG, etc), tracking often goes all the way to the maximum the software allows. I regularly get 130 yards with 0.264, and 180 yards with 0.308 diameter, though I shoot in an ideal area (see below).

B) If possible, set up your shooting lane with as little vegetation or obstacles as feasible.

Radar will bounce off anything in the cone, and this will reduce accuracy, precision, and tracking distance. I'm lucky enough to shoot in a wide open field, hence the great tracking I routinely get. Regardless, do your best to reduce interfering objects in the widest path you can to the target.

If you can't clear your shooting lane, I recommend just going out in your front yard and aiming the LabRadar straight up, and firing your rifle into the open air (assuming no trees, power lines, etc are going to interfere). Preferably you should use full auto like one does at a wedding celebration. You can get tons of data fast, and you don't have to worry about a backstop...

C) You need to get accurate atmospheric conditions at your location, though basic tools will do just fine. You just need Temp, Barometric Pressure, and Humidity (least important).

Get these values at your shooting position, and not some nearby place your phone weather app polled. Use actual station pressure (not corrected for sea level).

Take readings frequently, and record the time, particularly if the weather is changing (e.g. early morning, late evening). If the values are changing significantly during your session, LabRadar files have a time stamp, so use the environmental data you recorded closest to the shot when calculating B.C.

The B.C.calculation will be off roughly 0.001 (G1) per degree of temperature error, and .002 per 0.1 inHg pressure error. Small but significant if you just use a weather app that pulls data from an airport 15 miles away, or using data that you collected two hours ago before it got cloudy...

D) Aim and stabilize your LR carefully.

I highly recommend making or buying a sighting system. I epoxied a little piece of stainless tubing to my sighting V, carefully squared to the unit face, but you do you. For longer range tracking, aiming is important.

I have a gorilla pod tripod, but brace it all with small bag of lead shot on each leg. Probably 20 lbs on that sucker. Whatever you choose, make sure it isn't vibrating or getting off aim during tracking.

Check your aim periodically. I've lost entire strings of bullets because my LR wobbled off of aim because of my superb MBM brakes, an errant wind gust, or just poking buttons. I still got velocity readings, but not good tracking files.

E) Have your target a little further away than you can reliably track bullets if possible.

LabRadar will track through some types of targets (cardboard, foam board, maybe even wood/metal/unobtanium?), but the interference will degrade tracking. You're artificially limiting your tracking distance by placing a target between the bullet and the radar.

Here's how I setup. Note the clump of tall vegetation, just to the right of my shooting lane at the edge of where the tilled and harvested field meet about 30 yards out. That caused poorer than normal tracking for me during this session.

Data Extraction and Reduction

My spreadsheet is attached as a zip file below. When using my spreadsheet, you'll want to allow Macros (a pop up will show up when you open it). Excel (Microsoft in general) is pretty much the angry nanny of software, so if you don't have the option to unblock the macros when the spreadsheet opens, you can easily do so in the file properties (Click here for instructions on unblocking a file).

If you don't trust the macros, you can use it without them just fine, but will have to manually copy and paste data from the LabRadar file, and will lose the automatic sorting button.

Here is a YouTube video demonstrating the use of the spreadsheet and the free calculator from JBM Ballistics (Click Here for JBM). It's long and boring. It does point out some of the shortcomings in LabRadar's pre-programmed velocity interval data, which might be helpful to those who want accurate velocity readings, even if they don't plan to calculate B.C.



Concluding Remarks

This method is not as good as $100,000 dedicated doppler setups. It's only tracking for 100-200 yards after all. That said, if you're using G7 B.C., the velocity vs B.C. curve is usually pretty flat, so it should hold up to quite a ways out there.

This method is better than estimating the B.C. based on the bullet measurements.

This method is probably better than estimating the B.C. using shot drops (at least G7 B.C.), unless you have some serious skill, perfect weather, and lots of ammo. Since it's so easy, you should ideally be recording all the shots you are taking to confirm your D.O.P. E. at range, and calculating the B.C. (and velocity) simultaneously with both methods.

The more care you take in setting up your LabRadar for good tracking, collecting accurate environmental data, and thoughtfully inspecting the data, the better your results will be.

Now that I have my system down, setting up at the range only takes me 15 minutes or so. Culling the data and typing it into JBM takes about 1 minute per shot.

This method may seem a bit daunting to folks who don't use spreadsheets much, but it's no more daunting than telling a relatively new long range shooter how to calculate B.C. or "true" their velocity (bad idea) from shot drops.

My spreadsheet and data reduction is not the only way to do it. If you're an Excel whiz, please make your own and share. All you really need is way to get the best fit regression from the data array, and to use that to calculate the velocity at two points, and the distance between those two points.

Please let me know if you try this out, and if you have any troubles or questions.

 

[FEENIX]

Here's a relatively detailed description of my method for obtaining ballistic coefficient values using a LabRadar. I'm hoping that we as a community can start using a relatively standardized method to calculate B.C. and share those results. Something along the lines of the excellent Hammer Hunter load data thread.

I'm also hoping discussion can mostly avoid philosophical debates on the utility of B.C., manufacturer methods and motivations, etc, and focus on the nuts and bolts of the data gathering and processing using a LabRadar.

Perhaps with some good brainstorming, we can come up with a method that everyone who owns a LabRadar can use, so we can get some more "standardized" data out there. With that, we could begin to investigate variables like twist rate, velocity, and atmospheric conditions, and perhaps gain more insight on B.C. variability.

I also encourage anyone else with a method they use to start their own thread. Name it something easily searcheable with LabRadar and B.C. in the title though, so we can all find it and link it when searching and posting. I'm happy with my method, but no doubt others may have as good or better techniques they can share.

My method...

Tools you'll need...

1) LabRadar
2) An SD memory card installed while shooting. We want to use all the data we gather, not just the pre-programmed intervals that LR spits out (watch video for why that's a problem). A memory card is the only way to capture that on a LR.
3) Computer with Excel, Numbers, Open Office, etc. We're going to need to do a little data processing. My spreadsheet is attached below.
4) Weather monitoring tools. Kestrel, home weather meters, smart phone barometers, etc. We need reasonably accurate values for temperature, pressure, and humidity. These need to be at the shot location in real time.
5) Rifle, powder, bullets.
6) This one is the hardest to find...Primers.
7) JBM Ballistics free online calculator (their may be others, but this one works for me).

Setup

A) When programming your LabRadar, set the far velocity yardage to something MUCH greater than the unit will track.

The unit will stop tracking a few yards past whatever the furthest yardage you set. Instead, we want it to track as far as it can. I believe the maximum value you can set is 300 yards? For large diameter bullets (e.g. 44 mag, 50 BMG, etc), tracking often goes all the way to the maximum the software allows. I regularly get 130 yards with 0.264, and 180 yards with 0.308 diameter, though I shoot in an ideal area (see below).

B) If possible, set up your shooting lane with as little vegetation or obstacles as feasible.

Radar will bounce off anything in the cone, and this will reduce accuracy, precision, and tracking distance. I'm lucky enough to shoot in a wide open field, hence the great tracking I routinely get. Regardless, do your best to reduce interfering objects in the widest path you can to the target.

If you can't clear your shooting lane, I recommend just going out in your front yard and aiming the LabRadar straight up, and firing your rifle into the open air (assuming no trees, power lines, etc are going to interfere). Preferably you should use full auto like one does at a wedding celebration. You can get tons of data fast, and you don't have to worry about a backstop...

C) You need to get accurate atmospheric conditions at your location, though basic tools will do just fine. You just need Temp, Barometric Pressure, and Humidity (least important).

Get these values at your shooting position, and not some nearby place your phone weather app polled. Use actual station pressure (not corrected for sea level).

Take readings frequently, and record the time, particularly if the weather is changing (e.g. early morning, late evening). If the values are changing significantly during your session, LabRadar files have a time stamp, so use the environmental data you recorded closest to the shot when calculating B.C.

The B.C.calculation will be off roughly 0.001 (G1) per degree of temperature error, and .002 per 0.1 inHg pressure error. Small but significant if you just use a weather app that pulls data from an airport 15 miles away, or using data that you collected two hours ago before it got cloudy...

D) Aim and stabilize your LR carefully.

I highly recommend making or buying a sighting system. I epoxied a little piece of stainless tubing to my sighting V, carefully squared to the unit face, but you do you. For longer range tracking, aiming is important.

I have a gorilla pod tripod, but brace it all with small bag of lead shot on each leg. Probably 20 lbs on that sucker. Whatever you choose, make sure it isn't vibrating or getting off aim during tracking.

Check your aim periodically. I've lost entire strings of bullets because my LR wobbled off of aim because of my superb MBM brakes, an errant wind gust, or just poking buttons. I still got velocity readings, but not good tracking files.

E) Have your target a little further away than you can reliably track bullets if possible.

LabRadar will track through some types of targets (cardboard, foam board, maybe even wood/metal/unobtanium?), but the interference will degrade tracking. You're artificially limiting your tracking distance by placing a target between the bullet and the radar.

Here's how I setup. Note the clump of tall vegetation, just to the right of my shooting lane at the edge of where the tilled and harvested field meet about 30 yards out. That caused poorer than normal tracking for me during this session.
View attachment 393913

Data Extraction and Reduction

My spreadsheet is attached as a zip file below. When using my spreadsheet, you'll want to allow Macros (a pop up will show up when you open it). Excel (Microsoft in general) is pretty much the angry nanny of software, so if you don't have the option to unblock the macros when the spreadsheet opens, you can easily do so in the file properties (Click here for instructions on unblocking a file).

If you don't trust the macros, you can use it without them just fine, but will have to manually copy and paste data from the LabRadar file, and will lose the automatic sorting button.

Here is a YouTube video demonstrating the use of the spreadsheet and the free calculator from JBM Ballistics (Click Here for JBM). It's long and boring. It does point out some of the shortcomings in LabRadar's pre-programmed velocity interval data, which might be helpful to those who want accurate velocity readings, even if they don't plan to calculate B.C.



Concluding Remarks

This method is not as good as $100,000 dedicated doppler setups. It's only tracking for 100-200 yards after all. That said, if you're using G7 B.C., the velocity vs B.C. curve is usually pretty flat, so it should hold up to quite a ways out there.

This method is better than estimating the B.C. based on the bullet measurements.

This method is probably better than estimating the B.C. using shot drops (at least G7 B.C.), unless you have some serious skill, perfect weather, and lots of ammo. Since it's so easy, you should ideally be recording all the shots you are taking to confirm your D.O.P. E. at range, and calculating the B.C. (and velocity) simultaneously with both methods.

The more care you take in setting up your LabRadar for good tracking, collecting accurate environmental data, and thoughtfully inspecting the data, the better your results will be.

Now that I have my system down, setting up at the range only takes me 15 minutes or so. Culling the data and typing it into JBM takes about 1 minute per shot.

This method may seem a bit daunting to folks who don't use spreadsheets much, but it's no more daunting than telling a relatively new long range shooter how to calculate B.C. or "true" their velocity (bad idea) from shot drops.

My spreadsheet and data reduction is not the only way to do it. If you're an Excel whiz, please make your own and share. All you really need is way to get the best fit regression from the data array, and to use that to calculate the velocity at two points, and the distance between those two points.

Please let me know if you try this out, and if you have any troubles or questions.

Thanks again for taking the time and effort to share information.
Ed

 

[Pdvdh]

That's a bunch of information to digest. I've been calculating bullet BC values using my LabRadar for ~5 years.

I read your post, but I didn't open your attached document and analyze your excel program, macros, spreadsheet.

Interesting that you reliably record .308 bullet velocity out to 180yds. I normally lose data quality at 100-125 yds for 30 cal diameter bullets. So the past 3-4 years, I set my LabRadar to collect velocity out to 100yds. I record velocity data virtually every time I shoot. And then revisit my BC values again. Even with my 100yd data limit, I find very consistent BC values over time. Which bolsters my confidence that 100yd velocity tracking is sufficient to calculate solid G7 BC values. And that the LabRadar is reliably recording data, consistently over time.

How different would your calculated BC values be if you used velocity decay data over 100yds bullet flight versus 180 yards? Significant differences? The differences I see between 80yd and 100yd downrange velocity data has been minimal. 80yds of data would yield the same G7 BC value as 100yds of bullet velocity. Over time, I'll see variances of approximately +/- 0.003. Which I consider excellent...

Multiple reasons I continue to record LabRadar velocities and calculate my own BC values. The biggest being, I've learned I start with a truer G7 BC, when calculating one from bullets fired from my barrels. Compared to the manufacturer's value.

I do expect the tech level of your thread, and the described process, is going to exceed the interest level of most. For one reason or another. But I applaud your efforts.

 

[entoptics]

...Interesting that you reliably record .308 bullet velocity out to 180yds. I normally lose data quality at 100-125 yds for 30 cal diameter bullets. So the past 3-4 years, I set my LabRadar to collect velocity out to 100yds....

...How different would your calculated BC values be if you used velocity decay data over 100yds bullet flight versus 180 yards? Significant differences? The differences I see between 80yd and 100yd downrange velocity data has been minimal. 80yds of data would yield the same G7 BC value as 100yds of bullet velocity. Over time, I'll see variances of approximately +/- 0.003. Which I consider excellent...

...I do expect the tech level of your thread, and the described process, is going to exceed the interest level of most. For one reason or another. But I applaud your efforts.

Based on the piles of replies so far, I think you're way off on the interest level...

Funny enough though, I think your method of pulling the pre-programmed values might be just as much work as mine, as I'm assuming you'd have to manually record the near/far from the LabRadar menu or App, unless you're using the shot report file generated on the memory card. My method, once you have it down, involves a couple of mouse clicks, and then it provides the near/far in the spreadsheet.

As mentioned, I'm guessing my good tracking is a result of my excellent shooting location, though some credit probably goes to my aiming/stabilization scheme.

I've not yet done an experiment on tracking distance vs B.C. My thought is that the further the bullet has to decay, the more any local errors will be averaged out. If there's a 0.1% error in velocity associated with the LabRadar, then a 50 yard tracking file would compound the errors twice as much as a 100 yard tracking file. That said, it sounds like your method is very good if you're only getting 3 in the 3rd variation. I see far more than that with my method.

Regarding the pre-calculated velocity settings from LabRadar, you might check out this post #4 in this thread again (it appears I was actually replying to your comments back in 2018 )...

Calculating BC with LabRadar. It works!

Picked up a LabRadar a couple days ago. It's a very nice machine. Quick Review (though you've heard it all before). Pros - Easy to setup, appears very accurate (tested against ProChrono), can run two rifles side by side with a buddy without repositioning, amazing data collection, so far no...

www.longrangehunting.com

Firmware updates since that post have improved the issue a fair amount, but as I mentioned in the recent tutorial video, it still happens too often for my taste. For someone that collects a lot of data like you, it's probably less of an issue, as it's rare enough to average out over the long haul. For those that only shoot a few 3 shot groups to develop a load (or worse, those that fire 1 shot ladders looking for "nodes" ), it might end up being problematic.

 

[Pdvdh]

I do pull my LabRadar data off the shot report file, on the memory card. Below is a pic that shows how I manipulate the shot report file to obtain the desired velocity data. I set the LabRadar distances at 20 40 60 80 100 yards. Then the LabRadar shot report file provides the velocities at each of those distances. I program some Excel functions on the shot report file to evaluate the velocity loss per 20 yards for each bullet fired... As well as the total velocity loss across the 100yds.
Once I'm comfortable with the quality of the velocity data, I use the average velocities from all bullets fired.
I input the Avg MV into my ballistics program, input the atmospheric conditions from the Kestrel at the time/location I collected the velocity data, and then adjust the G7 BC input value until it best matches the Avg velocities collected for that batch of bullets.

Here's what my typical shot report file looks like, after some tinkering. I've deleted some frivolous columns, and added some Excel functions to help evaluate the data. I think you'll get the gist of it...

I own and use the Patagonia Ballistics ColdBore 1.0 Desktop ballistics program.

 

[adk hunter]

I worked hard reading the original post.
Marveled at the details and thought about math more than I had in a long time.

Then I resolved to accept who I am.
I want to play on the dozer, thought of my Grandmother making quilts like that and wish you would get rid of the factory cardboard box and get a case from Harbor Freight! The orange one of course.

I love my labradar.
Nice job getting all that intel from yours!

 

[med358-boise]

I am not sure what problem you are trying to solve? The purpose of mathematics is a decision, not a number.

I would assume the decision you are trying to make is "What is the proper hold/set of clicks?"

My understanding of BC calculations is that at the end of the day, they are extrapolations leading to a derived value. When I consider the preceding, inconjunction with:

1) Inside of 800 yards, trajectories are actually quite linear in 50-100 yard segments
2) Outside of 800 yards, minor mis-estimation of range will have a greater effect on drop errors that typical BC errors
3) Items 1 & 2, also aplly to wind.

Given the above, it would seem that actual recording of POI at various distance given a specific zero would be a more effective decision process than all the calculations because there appears to be nothing in your approach that is going to lead to a more accurate calculation of BC which would result in better decisions.


While I sincerely applaud the intellectual exercise, I don't see how the method described leads to better decisions than the method of relying on manufacturer's published data followed by actual field validation via shooting.

 

[Pdvdh]

Say what?

 

[VenatusDominus]

I do not own a LabRadar but have used a buddies I shoot with. I generally adjust my BC based on POI (the range I shoot at has steel from 100 to 1000 yards). I have used both Applied Ballistics software with my Kestrel 5700 and Hornady's 4DOF software and both give me accurate DOPE. Using LabRadar for MV data and numbers from Hornady's 4DOF program for 100 yard velocity (Hornady 6.5mm 147 ELD-M), I plugged the variables into the JBM Ballistics program and it gave me a G7 BC of .121.

This is quite different from Hornady's published G7 of .351 for this bullet. The numbers are: MV 3077, Far Velocity 2949, Chronograph Separation 100, Drag Function G7, Temp 74 F, Pressure 29.11 (non-corrected), Humidity 17.0, Alt 908. Atmospheric data was collected with my Kestrel 5700 and used in both the Hornady 4DOF and JBM Ballistics.

I understand Hornady's G7 may be exaggerated (though their 4DOF calculator is spot on with this round) but I can't see it being off by .230.

 

[entoptics]

I do not own a LabRadar but have used a buddies I shoot with. I generally adjust my BC based on POI (the range I shoot at has steel from 100 to 1000 yards). I have used both Applied Ballistics software with my Kestrel 5700 and Hornady's 4DOF software and both give me accurate DOPE. Using LabRadar for MV data and numbers from Hornady's 4DOF program for 100 yard velocity (Hornady 6.5mm 147 ELD-M), I plugged the variables into the JBM Ballistics program and it gave me a G7 BC of .121.

This is quite different from Hornady's published G7 of .351 for this bullet. The numbers are: MV 3077, Far Velocity 2949, Chronograph Separation 100, Drag Function G7, Temp 74 F, Pressure 29.11 (non-corrected), Humidity 17.0, Alt 908. Atmospheric data was collected with my Kestrel 5700 and used in both the Hornady 4DOF and JBM Ballistics.

I understand Hornady's G7 may be exaggerated (though their 4DOF calculator is spot on with this round) but I can't see it being off by .230.

Your "chronograph separation" distance units were set in feet instead of yards...

 

[VenatusDominus]

Your "chronograph separation" distance units were set in feet instead of yards...

Haha, I figured it was user error. I couldn't imagine the program would be that far off. Thanks for the correction.

 

[VenatusDominus]

Using the velocity numbers from the 4DOF program (and yards instead of feet ), the JBM Ballistics program gives me a G7 of .362 for the first 100 yards and a G7 of .317 from 900 to 1000 yards. If I use the MV and 1000 yard velocity I get a G7 of .341, and MV - 700 yards give a G7 of .351 which is the published G7 from Hornady for the 6.5mm 147 ELD-M. Based on this, wouldn't the 100 yard (or even 200 yard) LabRadar data yield a BC too high to produce accurate DOPE for long range shooting?

 

[entoptics]

Using the velocity numbers from the 4DOF program (and yards instead of feet ), the JBM Ballistics program gives me a G7 of .362 for the first 100 yards and a G7 of .317 from 900 to 1000 yards. If I use the MV and 1000 yard velocity I get a G7 of .341, and MV - 700 yards give a G7 of .351 which is the published G7 from Hornady for the 6.5mm 147 ELD-M. Based on this, wouldn't the 100 yard (or even 200 yard) LabRadar data yield a BC too high to produce accurate DOPE for long range shooting?

Your using one model based on drag coefficients to check another model based on ballistic coefficients, so it's hard to evaluate what's real (perhaps neither one is?), though there's nothing wrong with doing that thought experiment, and it provides useful insight.

What I can say is, those differences are relatively small in the scheme of things for extended hunting range. Using JBM's trajectory calculator, at 3000 fps, there's less than 2" POI difference at 700 yards (1 scope click), and only 50 fps velocity difference between a 0.341 and 0.362 G7 BC. Heck, it's only 5" and 65 fps at 1000 yards.

As another data point, I've got 89 LabRadar B.C. measurements of the 147 ELDM from my 264 WM, 1:8 twist, at similar velocities, and the average for me is 0.326 G7. I'm probably not a good enough shooter to tell the difference between 0.326 and 0.351 B.C. or 0.351 and 0.362. A 3 mph 90° wind vs 270° wind makes that much difference in the 4DOF app due to aerodynamic jump (I think that's why anyway). Using 0.326 in my calculator (Ballistic App) does seem to work pretty good for me though. I've tried 4DOF too, and it works pretty good too...

In summary, the variance among quality models should be relatively small, and your example demonstrates that nicely. It also demonstrates that a $750 consumer setup can get you within spitting distance of one of the world's most sophisticated ballistics laboratories.

 

[VenatusDominus]

Your using one model based on drag coefficients to check another model based on ballistic coefficients, so it's hard to evaluate what's real (perhaps neither one is?), though there's nothing wrong with doing that thought experiment, and it provides useful insight.

What I can say is, those differences are relatively small in the scheme of things for extended hunting range. Using JBM's trajectory calculator, at 3000 fps, there's less than 2" POI difference at 700 yards (1 scope click), and only 50 fps velocity difference between a 0.341 and 0.362 G7 BC. Heck, it's only 5" and 65 fps at 1000 yards.

As another data point, I've got 89 LabRadar B.C. measurements of the 147 ELDM from my 264 WM, 1:8 twist, at similar velocities, and the average for me is 0.326 G7. I'm probably not a good enough shooter to tell the difference between 0.326 and 0.351 B.C. or 0.351 and 0.362. A 3 mph 90° wind vs 270° wind makes that much difference in the 4DOF app due to aerodynamic jump (I think that's why anyway). Using 0.326 in my calculator (Ballistic App) does seem to work pretty good for me though. I've tried 4DOF too, and it works pretty good too...

In summary, the variance among quality models should be relatively small, and your example demonstrates that nicely. It also demonstrates that a $750 consumer setup can get you within spitting distance of one of the world's most sophisticated ballistics laboratories.

I love to collect and analyze data (probably the engineer in me) and then apply what I have learned to try and improve my shooting. Thanks for starting this thread. I'm now seriously considering getting my own LabRadar to start creating my own custom drag models.