What are you guys using for your information on your dope cards when shooting matches or just a day out at the range. Density Altitude or...... Looking for some different ideas when I don't have time to reference my Kestrel or a ballistics calculator. Looking to print or write something out on a card and use it on my wrist coach.
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If you know the altitude you'll be shooting at and approximate temperature, you can put together a dope-card that should get the job done. Air pressure variation "should be" small enough to not be a big factor. And humidity doesn't make much difference anyway.
I have charts for multiple density altitudes. What I did was figure out how much of a change in DA changed my data by .2 at 1k yards, then make charts incremented that amount. For my 6 Creedmoor, that's 1500ft DA, so I have -1500, 0, +1500, 3000, and 4500. If I am going out west, I might make one for 6k, as well. I put the data in a small Excel template I made, print them on cardstock, and get them laminated at the nearest office supply store in their heaviest laminate. I also have UKD solving charts that were made the same way, as well as 1MPH wind charts for my rifle and trainer.
Before I go to a match I will pull the physical altitude of the range from a map, and pull the weather forecast data for hourly temp/baro pressure, then I'll use JBM to create a full ballistics chart. I usually use the temp for late morning as the midpoint between cold morning and warm afternoon. I'll print a full page chart and throw it in my bag as a backup, and also print out a smaller chart that I put in my wrist coach. Nice to have a hard copy in case of electronics failure.
Links I use are:
https://www.daftlogic.com/sandbox-google-maps-find-altitude.htm
https://weather.com/
http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi
Links I use are:
https://www.daftlogic.com/sandbox-google-maps-find-altitude.htm
https://weather.com/
http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi
A day or two before a big match (one that warrants the effort), I'll take a guesstimate at the DA based on what it is currently and the weather forecast. Then I'll make charts , by hand, at the nearest even DA, and one 2,000 ft higher and 2,000 ft lower. So, if I look up (or measure) the DA at the match site and it's 5768 midday, I'll make up cards for 4,000 - 6,000 - 8,000. I'll "laminate" these with packing tape, durable enough for the day and easy to do myself.
If the stages and ranges are given out before the match, I'll even fill out a dope card for each stage the night before. Any shot longer than 600 or so, I'll put an asterisk next to it to remind me to reference the actual DA on match day and adjust my data if necessary. Anything I can do to easily reduce my workload during a match, I'll do it. I prefer to avoid electronics during a match if possible, and with my system I will 90% of the time.
If the stages and ranges are given out before the match, I'll even fill out a dope card for each stage the night before. Any shot longer than 600 or so, I'll put an asterisk next to it to remind me to reference the actual DA on match day and adjust my data if necessary. Anything I can do to easily reduce my workload during a match, I'll do it. I prefer to avoid electronics during a match if possible, and with my system I will 90% of the time.
I use a 5700 elite and typically use the applied ballistics custom curve. Thoughts?
I'm not Sheldon, but no matter what I started with (G1, G7, AB custom curve, Hornady custom curve, etc), I'm going to actually test my bullets out of my barrel, preferably with everything else as close to match conditions as possible. Once you have tested data, it's usually pretty straightforward to fit a solution.
Yep, exactly what Carl said. No matter what app or tool you are using you go prove the data in the field and come back home to tweak the settings in your calculator so they match up with real world results. My approach is generally get accurate velocity with a quality chrono, then make slight adjustments to the G7 BC based on long range 1000+ yard tested dope.
So you change the BC to make your dope match actual hits instead of changing your velocity?
Correct. I'm using a quality chronograph (magnetospeed) and I shoot enough inside 600 yards to know that the velocity is accurate and data is good. Changing BC a few points based on impacts at 1100 yards or so doesn't affect my data inside 600 yards, where if I adjusted velocity to true the long range data I would be affecting my dope at all ranges.
In super sonic flight you should be adjusting the MV, in subsonic flight you should be adjusting the drag scale.
Note that if you are on target at say 500 yards, and you change the BC itself you could alter your close range impact predictions when using a BC. So using either a ballistic calibration and adjusting drag scale or just using a CDM is a better option.
Which is all great if you are using the full applied ballistics engine with drag scale factor and proprietary custom drag models. You guys have a good product and it makes sense that you recommend using the things that you sell.
However, if a shooter is working with traditional inputs of G7 BC and muzzle velocity, it makes much more sense to use accurate velocity to true up their close range impacts (600 yards and in) and to use BC to true up the long range impacts.
Example... I shoot at at a target distance of 1200 yards which is mach 1.2 and want to true up my data. I can do that by either adjusting velocity or adjusting BC.
If I adjust BC, I can move the BC across a MASSIVE range without affecting my 500 yard dope. With a 105 hybrid I can be anywhere between .255G7 and .291G7 and my 500 yard dope remains the same. At 1200 yards that is a 1.1 Mil window that I can true my data with.
If I adjust my velocity to correct the 1200 yard data, I can only move it within a 40 fps window before I start affecting my 500 yard dope. And a 40 fps range is only a 0.3 mil window at 1200 yards that I can work with before affecting my close range data.
I've been using the CDMs for years now, and the only time I have had an issue with data is when I screwed something up, or when it was a known external influence (light condition, updraft from terrain).
Thank you very much for that detailed explamation. I will digest a little bit more of that and probably ask a few follow-up questions. But that is extremely helpful and the way you explained it made a lot of sense.
