Thread: Applied Ballistics app ZERO question

using the applied ballistics app for my 7mm RM i have entered a zero range of 200 yards, however when i look at the drop chart it shows the point of impact to be 0.7 inches above zero?

i just cannot get my head around this. the only thing i can think of is the scope height at 1.5 inches, but surely it should still be 0 at zero distance? what am i missing here?

despite this the app is functioning on longer range targets very well so i doubt i'll alter whatever is at play

i have a similar issue with the other rifle i have on the app

can anyone shed some light? thanks!

Have you left the angle on anything other than 0

Or You set your sight in conditions to sea level ( approx 29.8 inhg) and now your settings are above sea level or you have a different barometric pressure value typed in

Double check all your setting are in metric or imperial. I once entered pressure of 29.8 in the metric box (should be more like 1014)...makes a big difference.

Kj

From a distant memory are you zeroed in yard and got your data in metres?

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Yep just checked mine .
If I have a 200 yd zero with my table in metres I have -1 at 200m.
Easy peasy.
So either change your zero to 200 m or your data to yards or just use how ya set it up but at least you know what's going on!

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thanks guys, still no luck, i can't see anything incorrect from any of your ideas so far.

on the 'Add Firearm' entry page does anyone know what 'Elev. Correction Factor' and 'Wind Correction Factor' mean? i have these as 1

do you mind casting your eyes over the data entries i have made? shown below

the only other fields not shown are Spin Drift and Coriolis Effect, which i left both turned OFF for now

cheers!

Ammunition:



Environment:


Drop Chart: (note 200y 0.7 and 0.0 is approx 217y)

Tap the 'pressure is absolute' slider in your shooting environment.

With Alt set at 0 I don't think it should be having an effect, but worth a try.

@LOC
Atmosphere and all that has no effect on the calcs not showing a 0.0 in Path at your selected zeroing range.

The 2 things that affect zeroing height though are Loc Angle (yours is 0 so that's OK). The other thing is Zero Height.
I use Shooter and Zero Height is found in the selected projectile data under Zero Data, Zero Height.
If I change my setting from 0 (normal setting) to 0.7 I can replicate your result.
In Shooter 'Elev. Correction Factor' and 'Wind Correction Factor' are called exactly the same thing and I have never changed the values which are defaulted @ 1 - same as yours.

I believe Shooter and Litz's own app are very similar and Litz also supplies confirmed BC data for Shooter

Originally Posted by zimmer

@LOC

I use Shooter and Zero Height is found in the selected projectile data under Zero Data, Zero Height.
If I change my setting from 0 (normal setting) to 0.7 I can replicate your result.

thats just the thing Zimmer... I can bring it back to 0.0 at 200y if I enter 'Zero Height -0.7' -- just like you can replicate my 200y data by adding 0.7 so why am i getting this difference at 200y then? stumped...

in ammo data you have altitude at 1000ft try zeroing that might make a dif

I think the problem is your ammo data as carlhurley mentioned. You have altitude at 1000ft and pressure as 29.92Hg and atmosphere set at absolute. That means the pressure at 1000ft is 29.92Hg, therefore the pressure at sealevel will be more than this. The ballistic program essentially remembers the angle that the shot is fired at.
Your target is at 0ft and the same pressure, but atmosphere is not set as absolute.
Therefore the target is being shot at lower pressure, so less drag and the shot goes high.

If you use pressure is absolute, you need to set altitude to zero, and use the actual pressure at your height. 29.92Hg is average atmospheric pressure at sea-level. If you don't have something that can measure pressure then use 29.92Hg, put in the altitude you are at and DO NOT select pressure is absolute.
That should be fine out to approx 600 yds, but further than that you need to know the actual pressure at your height.

ok - that is an error in my entries - thanks for picking it up. unfortunately even after i change these values for both Ammo and Target to 0ft and 29.92hg there is still no change in the old 0.7in at 200y issue.... exactly the same drop chart values appear

good explanation re atmospheric influence on the trajectory, thanks.

is anyone else using the Applied Ballistics app that could check their inputs and see if they have a similar issue?

i have turned off the 'Enable Zero Atmosphere' slider so it will assume that the rifle is correctly zeroed at 200y no matter what altitude you are firing at, to keep it simple

Just a thought.. have a play with your 'zero' entries, try re-entering the distance of your zero and the '0's for the offset. I found that sometimes with Shooter, if you change distance or other format, and change it back, it gets a bit screwed up. Yards => Metres => Yards again etc.

Also just for the interest of diagnostics, maybe try sliding 'zero atmosphere' off, run your solution and look for any change. If nothing, you can just flick it back on.
(Nevermind, see you just tried this while I was posting)

Looking at the numbers, something must be confused somewhere.

You have zero set at 200, yet it isn't showing at 200 in your 'real world' run. So therefore, the computer either thinks something in the environment/atmospherics is significantly changed, or one of the numbers is being calculated as different to shown. If nothing else is working, you could also consider creating a new load profile, pretty well identical to the current one, just in case it's become corrupted somehow.

@LOC your question about elevation and windage correction factor is for when your scope turrets do not move exactly 0.25MOA or what ever graduation you have selected.
For example on my scope the turrets move more than 0.25MOA per click, closer to 0.3MOA per click. So I have a correction factor of about 0.8.
For example if I had to move 25" at 100 yds it would work out that 10MOA was needed, so it would multply 10MOA by 0.8 and show me 8MOA as my adjustment.