Range Report Dope on ballistic app not correct

[Mooseknuckles]

Went out Friday with my 300 win mag to my local range. Sat down to shoot the 500 yard target, pull up my ballistic app and check dope for 500. App said to dial 2.6 mils, so dial in, held for a little wind and first shot sailed over the target . So I dialed .3 mils down and hit dead center in the plate. Moved on to the 540 yard target, app said to dial 2.8 mil, dialed in on the scope and fired. Same thing, sailed over the target. Dialed down .3 mils and bang dead center.

I went to check all my data I had input into my ballistic app, everything looked correct but to get my app to line up with what I actually dialed I had to adjust my velocity up to 3100 FPS from 2860 FPS.
Here is the data I had enter into my app. The app I use is ballistic ae
Weather inputs are
Altitude 800, temp 80, humidity 75, baro 30.1

I have chronographed the rifle and over 5 shot the average is 2864.
load data for the rifle is
300 win mag
Norma brass, cci250 primer
H1000 77.1 grains
208 eldm seats at 3.650
Rifle data
Trued Remington 700
26 inch bartlien #4lt bull
Grayboe stock that is bedded
Timney 517
Silencerco harvester 30 suppressor.

So question is why is my dope so far off from what I actually dialed? I am pretty new to the app I have and I have to be screwing something up. Hope this ramble of a post make since.
If you guys need more data to help me out that I am missing let me know.
thank appreciate it

 

[nn8734]

I use Shooter as a starting point but that’s it. Also experience the same thing you - air mailing the target when relying on app data. Once my dope card is filled out with validated hold overs, the app is forgotten about and I rely on my manually recorded data as a starting point for subsequent sessions in different conditions or areas.

 

[_Windrider_]

Went out Friday with my 300 win mag to my local range. Sat down to shoot the 500 yard target, pull up my ballistic app and check dope for 500. App said to dial 2.6 mils, so dial in, held for a little wind and first shot sailed over the target . So I dialed .3 mils down and hit dead center in the plate. Moved on to the 540 yard target, app said to dial 2.8 mil, dialed in on the scope and fired. Same thing, sailed over the target. Dialed down .3 mils and bang dead center.

I went to check all my data I had input into my ballistic app, everything looked correct but to get my app to line up with what I actually dialed I had to adjust my velocity up to 3100 FPS from 2860 FPS.
Here is the data I had enter into my app. The app I use is ballistic ae
Weather inputs are
Altitude 800, temp 80, humidity 75, baro 30.1
View attachment 7388888
I have chronographed the rifle and over 5 shot the average is 2864.
load data for the rifle is
300 win mag
Norma brass, cci250 primer
H1000 77.1 grains
208 eldm seats at 3.650
Rifle data
Trued Remington 700
26 inch bartlien #4lt bull
Grayboe stock that is bedded
Timney 517
Silencerco harvester 30 suppressor.

So question is why is my dope so far off from what I actually dialed? I am pretty new to the app I have and I have to be screwing something up. Hope this ramble of a post make since.
If you guys need more data to help me out that I am missing let me know.
thank appreciate it

My first question is baro 30.1? Where were you shooting, Death Valley? Looks to me like you used a corrected barometric pressure instead of absolute pressure.

 

[Mooseknuckles]

My first question is baro 30.1? Where were you shooting, Death Valley? Looks to me like you used a corrected barometric pressure instead of absolute pressure.

I must have the barometric pressure off. I checked it using my app now and it says 29.92. I am located up in Washington.
This is at my house. Range is at 800 ft.

 

[shotdown]

I see a G1 BC of .661 for the 208gr ELDM. Since it’s lower, the Ballistic Calc will cause you to
dial more. However, the I got that .661 number from the Applied Ballistics app.
Also, if you are using corrected baro, you need to turn off “pressure is absolute”

 

[Mooseknuckles]

The app has the bc lower then what hornady advertises. The list a bc of .690, .696 was a guess off the top of my head.
Ok I have absolute pressure turn off and the app at 2860 is still telling me 2.86 mils.
I think I am going to have to validate the data by just getting out and shooting the rifle. Well obviously

 

[hafejd30]

Use your app data as a basic reference. Shoot at 100 (zero), 300, 500, 800 yds etc with accurate weather conditions. Then adjust the bc, speed etc until your drop on the app is as close as you can get to your real world data from shooting.

I have yet to see an app that didn’t require some type of tuning to make it accurate inside 1K

 

[_Windrider_]

The app has the bc lower then what hornady advertises. The list a bc of .690, .696 was a guess off the top of my head.
Ok I have absolute pressure turn off and the app at 2860 is still telling me 2.86 mils.
I think I am going to have to validate the data by just getting out and shooting the rifle. Well obviously

Ok next question, are you using a kestrel or a weather flow? You don’t want ballistic AE to pull the data from the www. For all you know that could be from an airport 150 mikes away. You said you are at 900 feet, but it shows 24? There could be a few issues, but I think your enviro data is part of the problem.

 

[shotdown]

Is your sight height correct at 1.9?

 

[Mooseknuckles]

Use your app data as a basic reference. Shoot at 100 (zero), 300, 500, 800 yds etc with accurate weather conditions. Then adjust the bc, speed etc until your drop on the app is as close as you can get to your real world data from shooting.

I have yet to see an app that didn’t require some type of tuning to make it accurate inside 1K

This is what I assumed I would have to do but figured I would run it by you guys that are way more experienced then me. I guess I need to pick a kestrel to get true weather conditions.
@TacticalDillhole
No I am not using a kestrel. I am pulling weather from the app. That could be part of my issue.
I am at 24 feet at my house. The range is at 800 feet. It is about 20 miles from my house.
@shotdown
Yes 1.9 is correct for scope height.

 

[hafejd30]

Ok next question, are you using a kestrel or a weather flow? You don’t want ballistic AE to pull the data from the www. For all you know that could be from an airport 150 mikes away. You said you are at 900 feet, but it shows 24? There could be a few issues, but I think your enviro data is part of the problem.

^ this guy nailed the weather portion. If your pulling from a weather app and not your actual location you can expect your data to be off. That holds true even after you establish your real world drop by shooting variable distance in the same weather conditions

 

[shotdown]

Got it, I could only get your data to line up with a 2.5” sight height.

Also, when you use station pressure (not corrected barometric) leave the “Pressure is
Absolute” on. If using corrected barometric, leave that off. I pulled up Seattle Washington in my weather app as an example, and corrected barometric pressure there now is 30.01. I was just trying to get a reference.

 

[Mooseknuckles]

^ this guy nailed the weather portion. If your pulling from a weather app and not your actual location you can expect your data to be off. That holds true even after you establish your real world drop by shoot variable distance in the same weather conditions

Definitely make sense now that I have it explained to me. Looks like a kestrel is in my future.

 

[hafejd30]

Anytime I work up a load for a rifle, be it mine or someone else I do the following in one shooting session after finding the proper load

1) sight rifle in at 100 yds then zero scope turrets/set zero stop. I also run a few round with the magnetospeed on to get velocity. Then enter known velocity and weather conditions into StrelokPro
2) test drop at 300, 500, 800 (for LR rifles)
3) write exact weather (baro, temp, humidity) in my reloading notes along with the drops
4) Adjust ballistic app (StrelokPro) so the drops match up with the current weather. It’s never perfect but usually can get fairly close (within 1/4MOA at every distance) I adjust the BC and speed mainly

It may not be a perfect method but works for me. However having weather conditions at shooting location is best vs a tower on your weather channel app. Most apps can account for FPS difference based on temp. So it’s important to see how that’s set up in your app. Especially if you use stable powder. My StrelokPro app accounts for 1 FPS for 1 degree in temp unless I change it. I zero everything so it doesn’t change on the app.

The baro and temp on mine seem to affect bullet drop more than humidity. I run the BC based on the G7 numbers not the G1

 

[Long Range 338]

Probably atmospherics as mentioned above, but when did you last chrono the rifle? How many rounds down the barrel and how many when you chrono'd? If you developed the data on a new barrel its feasible that the barrel has sped up and compounding that with minor atmospheric errors could explain the difference.

If it were me I would make sure to use a range book and document all the pertinent data as it will be useful going forward as you hone in on the root problem. Just remember the bullet doesn't lie.

 

[Shawn1492]

If you have an IPhone there is an app called My Altitude, it will get very accurate pressure and altitude readings at you location.
and Hornady 4DOF is free and easy to use. What does 4DOF give you for dope?

 

[pell1203]

There is another Free iPhone app called “Barometer” that provides pressure and GPS altitude at your location that works pretty well too.