Long Range Firing Solutions

[17LiveFree76]

My ballistic range finder is providing firing solutions that have my rifles shooting high. I have to add 200 fps to get my curve to hit at multiple ranges. The information I enter is accurate and I have tried using several rifles with the same results. Using the kilo 5 sig

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[Koda]

I have the same question.
Using the GeoBallistics app. But I think I had some data entered wrong.
I also dont know what "Metro" means and the choices on that are " ARMY or ICAO", under my bullet data.
so for me, data entry and learning the app.

But my question is, just how accurate or reliable these phone apps are?

 

[DLS]

Metro = Meteorological?

Just a guess based on ICAO being one of the choices in the category.

 

[P7M13]

I used Strelok, on my phone, for ~5 years. It worked well for me. My range finders were Leupold and Leica. I like the Leupy because it gives angle. Brunton for wind, elevation and temperature/RH.

 

[17LiveFree76]

I have the same question.
Using the GeoBallistics app. But I think I had some data entered wrong.
I also dont know what "Metro" means and the choices on that are " ARMY or ICAO", under my bullet data.
so for me, data entry and learning the app.

But my question is, just how accurate or reliable these phone apps are?

I have a friend that swears by shooter app. I downloaded it yesterday but the MOA it's providing me is still going to cause my point of impact to be too high.

 

[Member 66129]

Have you chrono'd the exact ammo you are using? Did you input the correct B.C, and environmental data?

 

[Member 34319]

I don't know what you put in value wise, but if you are willing to share it here, I bet a handful of us would input it into whatever app or calculator we have and see if it is a match or different than the Sig range finder.

 

[Koda]

My guess is it comes down to the difference between the published BC value and your actual BC value.

Also estimated atmospheric or environmental values may not exactly match where your at.

 

[YippeeKiYoRed]

Hornady and Berger have online apps you can use for comparison.

Air pressure and altitude make a difference. Example using Hornady 130 grain ELDM/6.5 Creedmoor: For Douglas Ridge I use 500 ft/29.4 in-hg. For COSSA I use 3500 ft/26.3 in-hg. The differences at 1000 yards are about 2 MOA and 230 fps bullet speed at the target. (in-hg = inches of mercury.)

 

[Certaindeaf]

Try the YEET app. You need to measure your arm accurately though.





Lulz

 

[Xmark1]

My guess is it comes down to the difference between the published BC value and your actual BC value.

Also estimated atmospheric or environmental values may not exactly match where your at.

BC is relative to many other variables.

Also, a headwind or tailwind, midflight, can alter POI. Same with changes in air density during TOF. And don't forget Coriolis Effect, the direction you shoot does effect your POI.

I use Strelok. It's a nice place to start, but I always have to tweak the numbers. I carry a logbook for each rifle I'm shooting and make detailed notes of actual results. This helps in future outings.

Interesting note about changes in temp. Yesterday I was shooting my 300WM about 400 yards. Midday my elevation dope was 5.75 MOA but by late day the temp had lowered by about 10 degrees, I had to change my dope to 6.25 to get the same POI.
Also, long ago, I drove my Harley from Sacramento to Tahoe in the early morning hours. As I went up and down through the foothills, temperature changes were very noticeable as I went up or down, it was cold!

 

[17LiveFree76]

I don't know what you put in value wise, but if you are willing to share it here, I bet a handful of us would input it into whatever app or calculator we have and see if it is a match or different than the Sig range finder.

300WM
Using the sig kilo5
My chrono is a Caldwell and velocity was 2875
Using 212g .308 hornady ELDx bullets G7 .334

When entering this info I hit around 1' high at 550 yards(estimated shooting at steel)
I had to enter 3150 for velocity to hit my marks at varies ranges out to 550

 

[Member 34319]

300WM
Using the sig kilo5
My chrono is a Caldwell and velocity was 2875
Using 212g .308 hornady ELDx bullets G7 .334

When entering this info I hit around 1' high at 550 yards(estimated shooting at steel)
I had to enter 3150 for velocity to hit my marks at varies ranges out to 550

Does the calculator ask for sight height and twist rate/direction?

What is the ammos SD?

What is the zero? What groups can we expect at that distance?

This process is sort of considered "truing your data" where you are finding your rifles ballistics with this round and bullet, which is not the test rifle used to get the numbers the manufacturer obtained.

For instance, say you shoot this round at 100 yards for your zero. This ammo usually prints 1.5" groups at that distance. That's going to be around 6" at 500 that is deemed acceptable. Add a few extra variables and that could easily be 1 foot off at 550.

 

[17LiveFree76]

Does the calculator ask for sight height and twist rate/direction?

Have you ever trued any of the data?

Sight height yes. Twist rate no. I have downloaded shooter app now that asks all of that and need to test it but I think it's going to have me shooting too high also. I have this issue with all of my rifles I use hitting too high unless I lie about my velocity

 

[Koda]

I have this issue with all of my rifles I use hitting too high unless I lie about my velocity

My guess is this means your actual BC is different than the bullets advertised BC.

 

[Member 34319]

Sight height yes. Twist rate no. I have downloaded shooter app now that asks all of that and need to test it but I think it's going to have me shooting too high also. I have this issue with all of my rifles I use hitting too high unless I lie about my velocity

Dang you replied before I could edit. See above.

 

[ORhutner]

I run Applied Ballistics which is a $30/app and never been bothered by the cost when you consider that is less than one wasted box of centerfire rifle ammunition these days. Have also run Strelok but won't be putting any more effort into that app until the stupid sanctions are lifted. Based on your comment that all your rifles are shooting high in comparison to the initial dope in your app it leads me to believe that either a setting isn't getting setup correctly or an input is consistently off. Have you compared your chrono's data to another chronograph to make sure it is pulling accurate velocities within an acceptable margin of variance?

I know this may sound like a really silly question but is your app setup for the proper unit of measure your using? We use a range that is setup in meters frequently and were told it was yards and did not verify each berm/target prior to starting to shoot. All our drop tables were in yards and we started to have a heck of a time 400 yards and out. Then one of us lasered the targets and found out everything was in 100m increments instead of 100yd increments. Adjusted our apps to meters and everything was back to spot on.

With good inputs for BC (G1/G7), twist rate, height over bore and velocity along with good environmental's I have only had to do very minor truing of ballistic data. Our typical process has us verifying zero at 100-yards while collecting chrono data, then input data into Applied Ballistics, fire a group at 800 yards to see if drop data is correct or we need to tweak ballistics to true to actuals and then take it out to 1000-yards plus. If we run into any issues at the longer distances we bring things back and trouble shoot. Does your app ask for what distance your zero is set at?

 

[YippeeKiYoRed]

I entered the data from Post #12 into Hornady's 4DOF calculator. I'm confused though. You say the original solution had your rifle shooting high. But adding 200 fps fixed it, meaning adding muzzle velocity made your rifle shoot lower?

Anyways, no mention of zero-range or scope height in Post #12 so I substituted 100 yards and 1.88" respectively. As you can see in the results below, adding 3150 fps lowers the come-ups at 600 yards by over 2 MOA.

So, what exactly is it you're trying to calculate?

MV=2875

RANGE (YDS) TOTAL COME UP (MOA) TOTAL WINDDRIFT (MOA) GYRO
0 0 0 3.23
100 -0.38 0.38 3.46
200 +0.93 0.8 3.72
300 +3.01 1.23 3.99
400 +5.4 1.69 4.25
500 +8.05 2.17 4.54
600 +10.95 2.7 4.86



MV=3150

RANGE (YDS) TOTAL COME UP (MOA) TOTAL WINDDRIFT (MOA) GYRO
0 0 0 3.26
100 -0.35 0.34 3.48
200 +0.59 0.69 3.73
300 +2.24 1.06 4
400 +4.18 1.45 4.3
500 +6.33 1.85 4.61
600 +8.68 2.3 4.9

 

[ferret427]

+1 for Applied Ballistics. They have custom drag curves for hundreds of projectiles they actually measured using some high-end doppler radar (not LabRadar, $100k type radar), and if I remember, measured past trans-sonic. Here's an article from Precision Rifle Blog about BC. Check it out, they talk about how not only projectile consistency but things like what kind of muzzle brake you are using can affect your BC.

Personalized Drag Models: The Final Frontier in Ballistics?

I am super-excited about this article! I've actually been working on it for a couple of months, and...

precisionrifleblog.com

My rangefinder has a built in weather station (wind meter run from cell phone linked to rangefinder) and uses BA drag curves.

 

[17LiveFree76]

Does the calculator ask for sight height and twist rate/direction?

What is the ammos SD?

What is the zero? What groups can we expect at that distance?

This process is sort of considered "truing your data" where you are finding your rifles ballistics with this round and bullet, which is not the test rifle used to get the numbers the manufacturer obtained.

For instance, say you shoot this round at 100 yards for your zero. This ammo usually prints 1.5" groups at that distance. That's going to be around 6" at 500 that is deemed acceptable. Add a few extra variables and that could easily be 1 foot off at 550.

This rifle is zeroed at 100 yards. I just shot 6 rounds and only have 1 hole in the paper. It's extremely accurate. 24" proof barrel on custom grind action rem 700. It shoots great out to 1000. The thing that baffles me is with this rifle and several others, I have to lie about my velocity to get the range finder to calculate my ark correctly. This causes me trust issues out past 500 yards