EXTREME RELOADING (SPECIAL EDITION): Calculate Ballistic Coefficient (BC) with the LabRadar

Did you know you can calculate ballistic coefficient using your Labradar? Do bullet manufacturers inflate the BC of the bullets? Check out this video and find out.
Links:
JBM Ballistics online www.jbmballisti...

[@bgeipel]

Excellent video! I have done something very similar with my Lab Radar. I also ran my calculated BC though a ballistics calculator and compared the intermediate velocity data in the calculated data to what my Lab Radar saw on my actual shoots - it was nice to see just how close the data is!

[@sdkweber]

Hello Barry, Thanks for watching and posting. That is another good use. So you were able to determine velocity at let's say 375 yards if so desired.

[@justice1327]

One of the best explanations I have seen on this topic. Keep up the great work. One thing I have done is to use Excel and creat the formula for determining the BC, as JBM does, in Excel. This way you don’t have to go back and forth.

[@sdkweber]

Is the conversion a direct, linear conversion? I agree it would be much easier in Excel but I do not know the conversion formula. Thank you for watching and posting.

[@sdkweber]

@Duane Reyelts Gladl to hear it Duane. Thanks for watching and posting.

[@skycam321]

Excellent content. LabRadar should be here tomorrow, can wait to use this information.

[@sdkweber]

I think you will like your LabRadar. Thanks for watching and posting. I am glad you found our video helpful.

[@OshoRamseyGump]

Title should read, Calculate Ballistic Coefficient with JBM Ballistics

[@benb1355]

That was really interesting and covered a use I hadnt considered - thanks for putting that video together!

[@sdkweber]

You are welcome. And thanks for watching and posting.

[@Rico11b]

Awesome video! I think the Lab Radar is a great device, however I question the validity of the down range velocity numbers. How can we be SURE that the data is spot on, and the velocities and ranges are EXACT? I mean the Lab Radar shows that it recorded a velocity at 100 yards. How can we know FOR SURE that the distance was EXACTLY 100 yards, AND the velocity was also accurate??? I'd love to see a series of videos from Lab Radar explaining the radar and how it works, and the accuracy of measurements from the different ranges it can track.

[@sdkweber]

Thank you Rico11b. I can't answer your question on the accuracy of the Labradar at range. I think I saw where some had folks had run a few Labradar units simultaneously and compared results. Again, if I recall correctly, they found the systems reported surprisingly similar results. However, if there were a systematic error in Labradar units in general, one would expect similar results. Ideally, Labradar would be compared against results from Oehler. I have not seen this done and it would need to be done very carefully to yield reliable results.

[@Rico11b]

@@sdkweber I found this video. kzbin.info/www/bejne/goWTZZuffLatmJo. In it the guy mentions that he talked with the Lab Radar folks about SNR, and he discusses it a bit. He also revealed that the radar captures a LOT more data than just Dx1-Dx5 data points. Very, very interesting.

[@sdkweber]

@@Rico11b Yes, there is an entire folder created for each session called the tracks (TRK). The track files record every velocity observation and by paying attention to the signal to noise value we can screen out bad data and use only the good data to calculate BC, etc. I think you will like the video we did looking at the track files kzbin.info/www/bejne/pauvpZSjpbBpbKM

[@asherdog9248]

It seems odd that Lab Radar dosent include BC as a standard computation?

[@Lin-pr8sh]

There are some acoustic chronographs that can also provide exterior ballistic information both BC and Cd as well as velocity data. Pendragon BCI has one available and Oehler system 89 (supposed to be out soon). They are more difficult to set up than lab radar, but they can provide better results especially on low cross-sectional area projectiles.

[@sdkweber]

Oehler was planning to release that about a year ago. I also have an Oehler 33 that I have used since the late 80's. It is excellent but truly a lot of work to setup. Thanks for watching and posting!

[@Lin-pr8sh]

@@sdkweber Yes, I found this quite informative. I have a lab radar and have used it to characterize bullet BC for a number of years, funny I used JBM as well. The thing I noticed is there tends to be a lot of scatter with labradar out to 100 yds - at least when I do it. If I look at the Velocity vs Distance data that lab radar has per shot. For a .308 cal bullet I generally only consider the data reliable to 60-80 yds. Not sure if you have looked at that before.

[@sdkweber]

@@Lin-pr8sh I have always used muzzle vs "as far out as I can get it", let's say 100 yards or even 150 yards. Are you seeing more variability in calculated BC at these distances compared to using muzzle and 50 yards? I have not tried it, but am not intrigued if I am understanding you correctly. Let me know if you have a chance.

[@Lin-pr8sh]

@@sdkweber Yes - I don't use the furthest out data point, or I curve fit the first 50 yds and extrapolate to 100 yds. The last data points can get very noisy. I am including a link to an image I saved on my google drive. I plotted the lab radar velocity vs distance in the lab radar track csv file. This round isn't too bad, I have seen worse, and better - but it can be somewhat variable. This is my experience - but maybe LR accuracy varies from unit to unit? drive.google.com/file/d/1Eec9ijCd6GGgSGBMLE1RZRXEygf1z0b8/view?usp=sharing

[@sdkweber]

@@Lin-pr8sh Thank you very much for sending this. I am going to look into this a bit more with my data. I wonder if you would see the same dispersion away from the trendline if you used time on the X-axis instead of distance. I have read that the LabRadar is a relatively weak doppler system (this is to make it affordable) which might explain the results. I think there is also a power setting in the unit. I need to double-check but may need to set mine to max or full power if possible.

[@saleembarmania5295]

Have you watched the Hornady podcast about bullet drag and ballistic coefficient?

[@sdkweber]

Yes, that was a good pod cast. It is also a timely question as we are releasing a new video very soon on calculating drag coefficient and analyzing variance with Labradar data.

[@saleembarmania5295]

@@sdkweber that's gonna be such a great vid! I look forward to it.

[@theaccountant5133]

ARE YOU CALCULATING FOR TEMPERATURE AND PRESSURE ON THESE NUMBERS?

[@sdkweber]

Air density is the important variable and it is used in the BC calculation. Temperature and barometric pressure are not part of the equation (of course, ambient temperature and barometric pressure influence air density).

[@YERAFirearms]

Use 2 Labradars, one near the target and one near the MV

[@ctclimberguy34]

Have you used your derived BC from your analysis & plugged that new BC into a ballistic app (strelok, geoballistic,kestralAB etc ) & used those numbers & shot it at extended distances 600-1000yds?.

[@sdkweber]

Not really. You will notice there is a range of BC's calculated using this method and the BC posted (in this case by Sierra) falls within that range. Thus, I have continued to use the BC posted by Sierra. But you raise a good point. I am now thinking about running more calculations to get about 100 samples and then use the mean or median of that value for my loads. Have you tried something like this? Thanks for watching and posting. Good question.

[@ctclimberguy34]

@@sdkweber I have not tried this. I don't have a Labradar (yet).

[@sdkweber]

@@ctclimberguy34 I think it is a good "chronograph". A bit pricey for sure. I also have an Oehler model 33 and it is very good, but it takes about 15-20 minutes to setup, several cables, etc. The Labradar simplifies all this and gives good results.