Managing the Wind
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www.snipershide.com Advanced Marksmanship Managing the Wind for a New Shooter
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Great stuff. I do want to delve deeper into understanding when your gun number changes based of distance/velocity. I’m sure that it’s pretty easy once you’ve identified where your projectile sheds if B.C. 1/10th. But that’s not something we commonly discuss.
I remember seeing the Sierra website where they assigned BC based off of velocity ranges. i.e. X cartridge had a G1 BC .475 from 2100-2750fps.
So if you turned those Velocities into distances. As in you drop below 2100fps, does your BC value drop to a .375 and in turn your gun number/ wind bracket become a 3MPH?
So if you turned those Velocities into distances. As in you drop below 2100fps, does your BC value drop to a .375 and in turn your gun number/ wind bracket become a 3MPH?
From the article:
As the bullet slows down, the B.C. changes; for a 308, this change might happen between 600 and 700 yards. For other calibers, it might happen later in the bullet’s flight. Recognizing this fact, we move the gun speed down, between 200 and 800 we have a 6 M.P.H. gun, at 900 to 1000 we have a 5 M.P.H. gun and after it drops to 4 M.P.H. This adjustment helps us manage the flight path and the changes in bullet speed.
Yeah, I read the article. Frank and I had this conversation in person before he wrote the article.
When can just make adjustments to Gun number artbitrarily and from experience. But I’m interested in the quantifiable numbers that would indicate it’s time to change wind number bracket.
Thank you for this article.
I’ve said it before and I’ll say it again. Jacks wind rose should replace everything in all military manuals.
Ya,
Ted's charts are amazing.
I think the BC banding is a valid way to look at this, for sure, I am not sure we can dig up enough of Sierra's data to build a basic yard line chart for us, like the 308, 6.5, etc.
If we can find that change, the location in space, we can then create a better chart
Ted's charts are amazing.
I think the BC banding is a valid way to look at this, for sure, I am not sure we can dig up enough of Sierra's data to build a basic yard line chart for us, like the 308, 6.5, etc.
If we can find that change, the location in space, we can then create a better chart
Where does a typical 308 go subsonic? Like 1100?
Depends on a couple of things, velocity, temp, etc,
I have seen them go weird just past 900 with the shorter barrels
I have seen them go weird just past 900 with the shorter barrels
Yeah the transonic area it always gets a little caddywompus. I was driving at we see the shift on 308 Around 600ish. 65 creed around 800ish. That’s 50% of the transonic range. Just trying to correlate where the shift occurs
Yeah. It’s correlating to the distance where the bullet is at 50% supersonic speed. That’s what I’m getting at. Center of pressure is moving as the bullet slows increasing drag and all that.
I’m driving at we see the 600 shift in a typical 308 because a typical 308 goes subsonic at 1100ish maybe even 1k. Just trying to establish a zone to start in.
Been running this method for a bit now.
It’s so easy people argue with me that it can’t be that easy.
I hope to test it out on really high G1 bc Bullets this winter
It’s so easy people argue with me that it can’t be that easy.
I hope to test it out on really high G1 bc Bullets this winter
While I know this topic is about wind correction. The topic of change in Bc and velocity came up and wanted to add this chart as a visual representation of an example of the drag increase that occurs in the transonic realm.
M1 is around 1125.
M1.8 is around 2025 fps.
M2.5 is around 2800Fps.
M1 is around 1125.
M1.8 is around 2025 fps.
M2.5 is around 2800Fps.
Could you clarify the question? Here are the 2 options.
1. when a BC and Velocity cause the initial gun number to drop a MPH (example: this gun is a 5 mph gun or this gun is a 7mph gun)
2. what yardage the gun MPH will step down for a given BC and velocity (example: at .55G1 and 2850fps this gun steps at 700,1000, and 1300yds)
Thanks
If gun number is derived from BC. And BC is semi dependent on Velocity. Is there a point where BC is degraded so much by velocity slowing down, that we could assign a new gun number? And if so, how do you quantify that?
If you haven't seen this, check out this thread. I worked on this last year a bit. This is where is started from.
https://www.snipershide.com/shooting/threads/extended-range-wind-gun-mph.6988053/
I stated the same method in August of 2019 here:
www.snipershide.com
It works just like Ted says it will.
It is pretty cool how a community of us can reinvent old methods and modify them to function well in the field. I likely never would have come across the bc method without the podcast Mike and Frank did. It should be the mainstream strategy for getting wind calls in my opinion.
As for figuring out where the shift from 7 mph to 6 mph to 5 mph happen, simply put the numbers in your favorite ballistic calculator and look at where the numbers line up for the conditions you are shooting in. Skookum had really good rules of thumb in one of the threads on making adjustments without electronics. He explained how to adjust for both DA and velocity.
If you make bedtime reading out of all of the threads on the subject here you will have a good understanding of the method as well as ways to make it really simple, or more complicated but also more accurate.
People put there own twist on it to get it to work for them depending on if they are shooting larger targets as fast as possible or if they need the accuracy to shoot smaller targets.
Calculating mph rifle
At a recent match, many on my squad were describing their wind calls in terms of mph, by saying eg: I used a 5mph wind( rather than describing it in terms of mils). These were good shooters doing this. (I just got on their squad by accident). Where can I learn about this technique, and...
www.snipershide.com It works just like Ted says it will.
It is pretty cool how a community of us can reinvent old methods and modify them to function well in the field. I likely never would have come across the bc method without the podcast Mike and Frank did. It should be the mainstream strategy for getting wind calls in my opinion.
As for figuring out where the shift from 7 mph to 6 mph to 5 mph happen, simply put the numbers in your favorite ballistic calculator and look at where the numbers line up for the conditions you are shooting in. Skookum had really good rules of thumb in one of the threads on making adjustments without electronics. He explained how to adjust for both DA and velocity.
If you make bedtime reading out of all of the threads on the subject here you will have a good understanding of the method as well as ways to make it really simple, or more complicated but also more accurate.
People put there own twist on it to get it to work for them depending on if they are shooting larger targets as fast as possible or if they need the accuracy to shoot smaller targets.
Awesome article thanks frank!
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