Drop Charts
- Thread starter Clayne_b
- Start date
Tom,
The feet apply to altitude, not distance. He's got different cards to adjust for air density.
fyi, you'd be better off creating these for Density Altitude instead of density with a fixed temperature. Guessing the "59" is 59F for standard conditions.
http://demigodllc.com/datacards.php
The feet apply to altitude, not distance. He's got different cards to adjust for air density.
fyi, you'd be better off creating these for Density Altitude instead of density with a fixed temperature. Guessing the "59" is 59F for standard conditions.
http://demigodllc.com/datacards.php
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Why BDC anything for LR simply doesn't work. A small change in the parameters and you have a huge error in result.
Remember this assumes your ammo AND BC remain the same at both altitudes..... It may not.
Jerry
No, he meant that it can change from lot-to-lot.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Sorry, should have been more specific and in this stuff... specific is a good thing.
Manf is such that bullets can change from lot to lot. A new die and the bullet can be quite different inshape.
But if you have made all your data based on a specific BC value, you are now wrong.
Then there is the actual velocity which can change due to changes in ambient conditions.
With any of this, you have to confirm in the real world.... which is why BDC products which assume a "standard" flight through the air is more then likely wrong
Jerry
One must take into consideration Density Altitude. Just because you may be at a known altitude, let's take 4000ft as an example, the actual density of the air may be anywhere from 2000-6000ft Density Altitude.
I have found major differences at different ranges and they DO make a significant change to your POI.
I have found major differences at different ranges and they DO make a significant change to your POI.
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Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
And this happens over the course of a day.... anyday.... everyday
Jerry
Jerry
Wow!!! I had now idea it was all this complicated!!! I thought recording come ups once for a given caliber/bullet/load, was all I needed!! from there sighters was all I ever needed,give or take a 1/4 1/2 moa. I've converted a lot of sighters for score. "Density/altitude" sounds like some new rocket science, or is it the same as relative air density?? that we studied faithfuly for 2-stroke carberated engines, except our sighters(jets) were blown pistons hehehe
It isn't a huge issue if you're shooting on a known distance range where you have sighter shots, target markers and people in the butts that can radio back feedback. It does become an issue when you're interested in making first round hits at different locations.
Density altitude is not the same as air density. Air density requires three variables: temperature, pressure and humidity. There can be multiple combination of the three that create the same air density. What density altitide does is essentially combine everything into one number. So, you only have one variable to keep track of. Weather meters like the Kestrel will give you DA.
Theres a proper explanation of it in the link I provided above...
Density altitude is not the same as air density. Air density requires three variables: temperature, pressure and humidity. There can be multiple combination of the three that create the same air density. What density altitide does is essentially combine everything into one number. So, you only have one variable to keep track of. Weather meters like the Kestrel will give you DA.
Theres a proper explanation of it in the link I provided above...
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So density altitude is RELATIVE air density?? I understand that if a known trajectory in a known air density is known, that through mathematical formula's the trajectory can be established for a differant desity altitude. However I have not found the guy at the range that has been able to read his Kestral and make the first shot be any closer to zero??? The military has sophisticated instuments to accomplish this and contrary to popular belief, snipers still usually require sighting shots for long range hits. I am sure that one could spend a lot of practice time studing DA and get a lot closer to centre on first shots, but that a lot of time I'm predicting! For jetting 2-stroke engines we had a guage that expressed relative air density as a percent, and had a adjustable ring around it, that whenever, whereever you established the right jet you set the ring for that size jet at that RAD reading. As the RAD changed the ring would do the math for you and indicate the appropriate jet!! easy peasy! Maybe I could bring out my RAD guage and establish some sort of correlation to bullet drop??? Or not! maybe I'll use the time recording my actual practice results until someone gives me actual proven results hehehe!
Sometimes I think the more experienced shooters on here get into to deep of topics for the less experienced ???
Marc
If you want a thorough explanation, try this:
http://wahiduddin.net/calc/density_altitude.htm
Maybe you aren't shooting with the right group of guys. At many of the sniper shoots down in the, you only get two shots at eack unknown distance target. The targets can be out past 1000 yards. Here, at the NSCC Precision Rifle competition, there is a side match known as the sighters match where the score is all of the sighter shots out to 800 meters. The guys who win it typically shoot all bulls.
Doesn't need to be complicated. With a weather meter and a good ballistic calculator on your phone, you just plug in the numbers and it spilts out a solution. Give it good data, and it will give you a good solution. Input garbage, and you'll get garbage back...
http://wahiduddin.net/calc/density_altitude.htm
Maybe you aren't shooting with the right group of guys. At many of the sniper shoots down in the, you only get two shots at eack unknown distance target. The targets can be out past 1000 yards. Here, at the NSCC Precision Rifle competition, there is a side match known as the sighters match where the score is all of the sighter shots out to 800 meters. The guys who win it typically shoot all bulls.
Doesn't need to be complicated. With a weather meter and a good ballistic calculator on your phone, you just plug in the numbers and it spilts out a solution. Give it good data, and it will give you a good solution. Input garbage, and you'll get garbage back...
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
You do more to set up your scope, confirm tracking, confirm zeros, confirm load tuning over varied conditions, etc, etc, etc.
I know you are confident that when that shot arrives on target, that spotter is telling you the right info to adjust.
Most LR shooters and hunters, don't put in this much effort and too many depend on tech or at least what they are told the Tech does, for their lack of practise and preparation.
All of this is as simple or as complicated as one wants BUT if trying to hit a small object way out there is the goal, depending on a bunch of generated numbers may not lead to success.
Jerry
I hope not too many of the guys I shoot with read this one!! hahaha
How big is your bull???
I have a hell of a time getting a drop chart that is within a 1/4moa after inputting all the data as accurratly as possible??? maybe I'm missing something
