Labradar can track 485g 45-70 bullets to at least 200 yards!

[JimGnitecki]

My buddy told me recently that the range to which the Labradar can track a bullet's velocity varies notably with the size and shape of the bullet. He said that shooting the big fat 485g 45-70 bullet (that I have been trying to find a good handload for and have failed), I MIGHT find that I can track it beyond the 150 yards that I had assumed was the Labradar's limit. He was right.

At yesterday's range session, I extended the requested distancess from a maximum of 150 yards to 175 and 200 yards as well. The Labradar DID provide velocities for both the 175 and 200 yards ranges, although only for about 70% of the rounds fired at 175 yards, and 57% of the rounds fired at 200 yards. But those 70% and 57% velocities looked reasonable and consistent, although the SDs of the velocities were higher at those longer distancess than they were for shorter distances.

So, if you are shooting large bullets, and using a Labradar to track their velocity, your Labradar's working range might surprise you, as it did me.

Jim G

 

[JimGnitecki]

By the way, extending the measuring range of velocity versus distance for that 485g Lee bullet showed that indeed the BC is falling ramatically as the bullet slows, and in fact at 200 yards, it is at the same velocity as at 175 yards:



Very strange. And causes me to again wonder: Is this some strange transonic effect? If so, is that why this bullet refuses to group better than 2 to 3 inch 3-shot groups by the time it gets to 150 meters = 163 yards, even though it grouped fine at 100 yards?

Jim G

 

[ms6852]

I just learned something today. Was not aware the Labradar could track velocities through the distances. I just have the chrono that most of us have shot or will shoot one day. Now I might put this on the bucket list to buy.

 

[Gordon]

By the way, extending the measuring range of velocity versus distance for that 485g Lee bullet showed that indeed the BC is falling ramatically as the bullet slows, and in fact at 200 yards, it is at the same velocity as at 175 yards:

View attachment 1172694

Very strange. And causes me to again wonder: Is this some strange transonic effect? If so, is that why this bullet refuses to group better than 2 to 3 inch 3-shot groups by the time it gets to 150 meters = 163 yards, even though it grouped fine at 100 yards?

Jim G

Quite possibly it is a trans sonic effect. Some , most infact bullets do experience buffeting in that range which can mean un predicable bullet movement. I have also found that velocities do not drop as predictably in the 200 fps or so range of the trans sonic area of travel. Things are pretty normal out of that area. Note that is why certain cartridges have problems in really long range work. Most .308 Win. loadings for long distance work go trans sonic range around 1000 yards, more or less.

 

[25-20 WCF]

…although the SDs of the velocities were higher at those longer distancess than they were for shorter distances.…

That could be due to the smaller sample size so they are not really comparable. I’ve used my Labradar to confirm the actual BCs of various bullets in various calibers; some bullets match the published BC pretty closely, others are further away. (I use the Hornady ballistic software to estimate the BCs so take that into consideration).


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[AJC1]

The base of your 45 caliber bullet is large enough to get good signal to noise ratio for a return. A boatail 22 is exactly the opposite... if the data helps you great. You may play with the sensitivity settings for best results