Density Altitude In Shooter App?

[TX_Diver]

Got out and shot yesterday for the first time since buying Shooter App. Would appreciate some feedback on if I'm doing this right or if I have an error somewhere.

6.5CM - 147 ELD-M - 2513 FPS MV (avg of 10 shots over a magentospeed at around 70 F) - 41.0gr H4350 - Starline Brass - CCI LRP

Shooting yesterday at 4,000' Elevation and about 102F.

I put all that into Shooter app and after getting a zero based on an 18 shot group (.2 down and .1 left from top group) then check with 5 shots on the blue tape I went out to ~500 and 600 yards.

At 495 yards I dialed in 3.0 Mil which was the Shooter dope for 495 yards. 5 shots were roughly 9.5" below my waterline. Dial another .5 to 3.5 and I'm pretty well on there.

At 610 Shooter gave me 4.0 Mils and after chasing my tail on steel for a few min I went back to paper and found I needed to dial 4.5 Mils. No pic of this one.

When I enter DA in the app it has a spot to put "Density Altitude" and "Temperature". I was at 4,000' Elevation and it was just over 100 F, so using a DA chart I got a DA of 7,500'. When I put it in the App though I put in 7,500' for "Density Altitude" and 100 for "Temperature"

Now after playing with it today I'm wondering if I wasn't supposed to put my actual altitude there and let the app calculate DA. If I put 4,000' and 100 F it gives me 3.3 Mils at 495 and 4.5 Mils at 610. If I was just supposed to put DA in the app why would it care what the temp was (since powder temp has it's own input)?

If anyone wants to sanity check me or point out what I'm doing wrong that'd be appreciated! I can play with velocity truing but it seems like .5 Mils is more likely an error on my part.

 

[Formidilosus]

When I enter DA in the app it has a spot to put "Density Altitude" and "Temperature". I was at 4,000' Elevation and it was just over 100 F, so using a DA chart I got a DA of 7,500'. When I put it in the App though I put in 7,500' for "Density Altitude" and 100 for "Temperature"

Now after playing with it today I'm wondering if I wasn't supposed to put my actual altitude there and let the app calculate DA. If I put 4,000' and 100 F it gives me 3.3 Mils at 495 and 4.5 Mils at 610. If I was just supposed to put DA in the app why would it care what the temp was (since powder temp has it's own input)?

The temperature is there when using DA because it’s needs it to calculate the speed of sound.

Changing the temp from 0° F to 100° F does not change your trajectory at 610 yards. It’s only .1 mil difference at 800 yards.

If anyone wants to sanity check me or point out what I'm doing wrong that'd be appreciated! I can play with velocity truing but it seems like .5 Mils is more likely an error on my part.

You have an input off somewhere.

 

[ElPollo]

That’s interesting. The version of Shooter on my iPhone doesn’t have an option to enter density altitude, just altitude. I’ve played around with it a bit and it seems to default to calculating DA if I enter altitude and temp. At least the addition of a barometric pressure doesn’t seem to change things substantially inside of 600 yards.

Here is a DA chart:

 

[Formidilosus]

That’s interesting. The version of Shooter on my iPhone doesn’t have an option to enter density altitude, just altitude. I’ve played around with it a bit and it seems to default to calculating DA if I enter altitude and temp. At least the addition of a barometric pressure doesn’t seem to change things substantially inside of 600 yards.

Here is a DA chart:

Go into the setting for the app and select “use density altitude”, then close the app and reopen.

 

[ElPollo]

Go into the setting for the app and select “use density altitude”, then close the app and reopen.

There doesn’t appear to be a way to get into setting in the version I have. It does not line up with the directions that Shooter provides to edit the settings either. It’s perplexing.

 

[Formidilosus]

There doesn’t appear to be a way to get into setting in the version I have. It does not line up with the directions that Shooter provides to edit the settings either. It’s perplexing.

Android or apple?

 

[ElPollo]

Apple

 

[atmat]

Apple

It’s not in settings withim the App.

Go to your home page —> Settings —> Scroll down to where it starts showing your apps and select Shooter.

It took me way too long to find it because I was searching for the settings within the app, when it’s not there

 

[Formidilosus]

Apple

As atmat wrote, it’s in the main settings on your phone. Not within the app.

 

[TX_Diver]

Getting to DA took me awhile too lol.

Here's my inputs. When I do this today it gives me 4.4 or 4.6 Mils at 610. Not sure what I changed between them.

Frustratingly even if I use velocity calibration and when it says 4.4 it doesn't change it. If I use velocity calibration when it initially says 4.6 mils, and I input 4.5 at 610, then it tells me 4.4 mils after.

At that point I think I'm close enough, but I'd really like to figure out why it varies slightly.

 

[ElPollo]

It’s not in settings withim the App.

Go to your home page —> Settings —> Scroll down to where it starts showing your apps and select Shooter.

It took me way too long to find it because I was searching for the settings within the app, when it’s not there

Holy crap! That was helpful. Thanks!

 

[TX_Diver]

So I just recalculated and now I get a different solution...

On a side by side comparison I notice the stability factor changes from 1.89 above to 1.9 below... but I don't see anything else changing?

 

[Formidilosus]

Have you measured your powder temp MV difference?

 

[TX_Diver]

Have you measured your powder temp MV difference?

Yes, albeit with a small sample size for the colder rounds.

It was a few weeks ago before I moved and was only with 3 rounds. I haven't finished unpacking from the move so my data book is still missing, but from memory I left a magazine in the freezer for 2-3 hours, checked it with the IR temp gun and it was around 6F. I then shot those 3 quickly and want to say there was about a 15 FPS between the average of those 3 shots and 2513 which was my 10 shot average when it was about 75F.

If I didn't do that right I will throw some rounds in a cooler this weekend and try it again. It's an hour to my shooting spot now though whereas a few weeks ago I could shoot off the porch.

 

[Formidilosus]

Yes, albeit with a small sample size for the colder rounds.

It was a few weeks ago before I moved and was only with 3 rounds. I haven't finished unpacking from the move so my data book is still missing, but from memory I left a magazine in the freezer for 2-3 hours, checked it with the IR temp gun and it was around 6F. I then shot those 3 quickly and want to say there was about a 15 FPS between the average of those 3 shots and 2513 which was my 10 shot average when it was about 75F.

If I didn't do that right I will throw some rounds in a cooler this weekend and try it again. It's an hour to my shooting spot now though whereas a few weeks ago I could shoot off the porch.

That is not enough of a difference to be factoring right now.

You have a lot going on in the app. You need to simplify it. Turn off all the extraneous stuff- just use a single G1 BC of .697. One MV. No spin drift, Coriolis, etc.

 

[TX_Diver]

That is not enough of a difference to be factoring right now.

You have a lot going on in the app. You need to simplify it. Turn off all the extraneous stuff- just use a single G1 BC of .697. One MV. No spin drift, Coriolis, etc.

I thought I had all that stuff turned off lol. I started using Shooter as it appeared simpler!

The toggles for that stuff were off, but I just went into settings again and found "Simple" and "advanced" and saw I could disable some more features. Thanks! I switched that to simple and disabled almost everything else.

Current settings:

With the singular BC of .697

With 3 BC Values

On the off chance that since my MV is more inline with the second BC value Hornady published I tried that as a single BC also but it didn't make much difference.

All of these are getting much closer though so I appreciate the help!

 

[Flyjunky]

@Formidilosus

At what range do you enable spin drift?

Last year we spent the day shooting from 800-1200 and I experimented with it in shooter. It seemed to help with more accurate impacts but it was only about 25 shots and it was an inconsistent wind day. So I don’t know if it was just me imagining it or not.

 

[Formidilosus]

@Formidilosus

At what range do you enable spin drift?

Last year we spent the day shooting from 800-1200 and I experimented with it in shooter. It seemed to help with more accurate impacts but it was only about 25 shots and it was an inconsistent wind day. So I don’t know if it was just me imagining it or not.

If I think about it and there is absolutely zero wind, I will account for spin drift by using a left .2-.3 mil correction in my holds starting at about 900’ish yards. But, I don’t really care all that much either, and hits rates don’t dramatically change when I don’t use it. I’m most often shooting in windy, broken terrain and the wind error swallows the error from spin drift.


If I have a complete precision shot with no setup time crunch I will use spin drift at 700+ yards, and multiple wind inputs as well all in the app.

 

[Flyjunky]

If think about it, and there is absolutely zero wind, I will account for spin drift by using a left .2-.3 mil correction in my holds starting at about 900’ish yards. But, I don’t really care all that much either, and hits rates don’t dramatically change when I don’t use it. Im most often shooting in windy, broken terrain and the wind error swallows the error from spin drift.


If I have a complete precision shot with no setup time crunch I will use spin drift at 700+ yards, and multiple wind inputs as well all in the app.

Makes sense, thank you.

 

[Formidilosus]

Makes sense, thank you.

Yes sir.