What ballistics app are you using on your mobile device? and an Applied Ballistics specific program question.

[Varminterror]

I think one could learn decades worth of conditional corrections, from live fire, in 30 min worth of playing with the 4DOF app.

Absolutely - and I can vouch for that, LITERALLY, in my personal experience.

I grew up calling the local Co-op to get weather data when I started shooting long range, and we made data cards - DOPE - which cataloged trajectory for the day against other conditions. We'd pick a standard condition, then have columns on a range card then based on that DOPE which showed "+.25 for every XX degrees temp" or "+.25 per increased humidity". In college, I learned about Density Altitude, so then we had columns for "+.25 per YYYft DA" and at one point, I printed multiple range cards which varied by 500ft DA, from 500 to 3500. Some of that trajectory was predicted from databases, such as the trajectory tables included in the back of the Speer reloading manual, corrected with DOPE for actual environmental conditions.

Today, all of that is condensed into a calculator on my phone or on my Kestrel, not a database, which has the ability to produce nearly infinite combinations of environmental conditions to produce extremely accurate predicted trajectories. I made my first Ballistic Calculator in Excel around 2004, and transferred it to a PalmPilot for use in the field, but the air density calcs were clunky at best. Now, I have almost a dozen ballistic calculators on my phone to do the job even better.

But... Garbage in, Garbage out... If we don't have good inputs, we don't get good outputs. For example, using 1300ft physical altitude when it's 2500ft DA actual air density.

 

[JFrank]

I'd bet dollars to doughnuts the error is between physical altitude as an input on the site vs. Density Altitude. Berger's site calculator isn't very clear that the "Altitude" for their inputs is actually "Density Altitude," not physical altitude. Inputting my physical altitude, right now, and comparing against the conditions I shot on Sunday with my well-trued and proven calculator (thousands and thousands of shots confirmed against that trajectory), I get 1, 2, 3, and 4 tenths mils error for 7, 8, 9, and 1000yrds. If I input the correct Density Altitude into the "Altitude" box on Berger's site, the trajectory comes perfectly in line with what StrelokPro kicks out for my known true trajectory. And vise versa, if I put my physical altitude into StrelokPro instead of Density Altitude in the DA box, then I get the exact same trajectory (down to the 1/100th mil) as I get from Berger's site if I use physical altitude on their site as well...

So it's a misidentification on their site - "Altitude" should be "density altitude," which is really only obvious for folks REALLY familiar with the air density calcs, because Berger's site only asks for Temp and Altitude, which would also require baro pressure and dew point (or percent humidity) if physical altitude were the correct input.

I’ll have to study up on that a bit more.
Thank you

 

[Varminterror]

I’ll have to study up on that a bit more.
Thank you

We've had match days where I've gone from -500ft to 2000ft DA, and at the same range, later in the season, we've seen as high as 4500ft. In a nutshell, DA is an "equivalency" to standardize changing environmental conditions at different physical altitudes. Not so different than the difference between Station/Absolute Pressure and Barometric Pressure - DA is just a means to standardize different environmental conditions. So when my DA is showing 2500ft on the Kestrel, even though I'm standing at 1200ft physical elevation, that means the environmental/atmospheric conditions are ACTING as if I was at standard conditions at 2500ft physical elevation, instead of 1200ft.

 

[Walkalong]

One more reason to use AB on a Kestrel, it calculates all of that for you where you are at.

 

[JFrank]

Well, I have a Birthday coming up, maybe my wife will look into that Kestrel thingy.
Probably not since I just paid for another new barrel and Tom will call any day with my bullet order ready.

 

[Varminterror]

I just paid for another new barrel

I can't decide if I'm lucky, or not so lucky this week. I had two barrels from Bartlein finish a month early, and a prefit barrel from Proof finish two months early, so I had to pay for a lot of steel this week... After my new Manners just finished up and had to be paid last month (REALLY didn't love that pricetag on their big monster), my fun budget sure took a beating the last ~3wks.

 

[JFrank]

I can't decide if I'm lucky, or not so lucky this week. I had two barrels from Bartlein finish a month early, and a prefit barrel from Proof finish two months early, so I had to pay for a lot of steel this week... After my new Manners just finished up and had to be paid last month (REALLY didn't love that pricetag on their big monster), my fun budget sure took a beating the last ~3wks.

Dude, I waited 16 months for my Krieger order, if I hadn’t won a certificate for xx off the price I would have grabbed a Brux or Bartlien no waiting.