Horus ATragMX software considers atmospheric conditions, gun data, ammunition, range, speed and muzzle velocity to calculate precise aiming solutions with "come-up" results – and even accounts for Coriolis and spin drift effects. ATragMX, loaded on a handheld computer made by TDS Recon, is easy to use and lightning-fast. The Recon meets the rigorous MIL-STD-810F military standard for drops, vibration, humidity, altitude and extreme temperatures.
- Open the [Range Card]({{ site.baseurl }}/wiki/feature/rangecard.html) and check the ammunition: bullet diameter, bullet weight, rifle twist, muzzle velocity at 15°C, zeroed distance and bore height.
-`Dir of Fire (deg from N)`: *The value is therefore given as the direction of the barrel axis from true north.* [Horus manual p.14]
-`Wind speed (m/s)`: *Two wind speed values (low and high) may be entered on the target screen,[...] Lead/Wind2 button on the screen.* [Horus manual p.32]
- Wind takes into account geographic location, season, time of day, obstacles, altitude and surface roughness: [Wind Profile](https://wind-data.ch/tools/profile.php?lng=en).
-`Wind Direction (clock)`: *Wind Direction is expressed in clock points.[...], wind is always described in terms of where it is coming from.* [Horus manual p.16]
-`Inclination Angle`: *The degrees field is marked with a “d” and the cosine field with a “c”.* [Horus manual p.33]
- Apply vertical (Page Up and Down keys as default) and horizontal (Left Ctrl + Page Up and Down keys as default) elevations to the [scope]({{ site.baseurl }}/wiki/feature/scopes.html).
- Hold Breath (Left Shift as default) and Fire (Prim. Mouse. Btn. as default).
> This process is called “Truing Drop”, or simply “Truing”. It involves taking 2 or 3 real flight data points (finding bullet drop at 2 or 3 places along its flight) and feeding it into the calculation parameters. [Horus manual p.23]
> The Truing Drop function is opened from ATrag’s main screen by selecting “Options” [...], then selecting “Truing Drop” from the menu that appears. [Horus manual p.23]
- The `Default zero distance` can be overwritten with the [Scopes Options]({{ site.baseurl }}/wiki/feature/scopes.html), the [Scopes Framework]({{ site.baseurl }}/wiki/framework/scopes-framework.html) or the [CBA Settings System](https://github.com/CBATeam/CBA_A3/wiki/CBA-Settings-System).
- Open the [Range Card]({{ site.baseurl }}/wiki/feature/rangecard.html) and check the ammunition: **bullet Class Name**, bullet diameter, bullet weight, rifle twist, muzzle velocities, zeroed distance and bore height.
- Open the AtragMx and the `Atmsphr` column, select `Default` and `Done`.
- *The AtragMx accepts only **G1 ballistic coefficient**.*
- *G7 ballistic coefficient can be converted, for example, with the online [JBM Ballistics Calculators](http://www.jbmballistics.com/cgi-bin/jbmgf-5.1.cgi)*.
> Note: The ballistic coefficient can be calculated by using the [360 Degree Training Course mission](#5-resources) as a chronograph at different distances and [JBM Ballistics Calculators](http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi) for example, an another ballistic software at your own convenience, or the [AtragMx Truing Tool](#33-example-with-truing-tool).
- Check target's [slope distance and azimuth]({{ site.baseurl }}/wiki/feature/vector#23-slope-distance-and-azimuth) (hold both R and Tab keys as default).
- Open the [AtragMx properly configured before](#32-example-with-m14-and-default-762mm-20rnd-mag) according to current rifle and ammunition.
### 3.8 Example with AtragMx and default ballistic (M14, 7.62mm 20Rnd Mag)
> Note: ACE3 has two external ballistics, the vanilla default ballistic (enabled as default) and the [Advanced Ballistics]({{ site.baseurl }}/wiki/feature/advanced-ballistics.html) (must be enabled). The ACE3 default ballistic doesn't take atmospheric conditions (except wind), powder temperature, rifle twist and Earth effects into account. The AtragMx will need for `Gun` column: `Bore`, `C1 Coefficient`, `Muzzle Velocity` and `Zero Range`. With `Target` column, `Latitude` and `Dir of Fire` are useless. `Atmsphr` column must not be updated.
**Start of the mission:**
- Open the [Range Card]({{ site.baseurl }}/wiki/feature/rangecard.html) and check the ammunition: **bullet Class Name**, muzzle velocity, zeroed distance and bore height.
- Update the `Target` column and `Done`. Requirement: [Wind arrow]({{ site.baseurl }}/wiki/feature/weather.html), [Protractor]({{ site.baseurl }}/wiki/feature/advanced-ballistics#22-protractor), [Map Tools]({{ site.baseurl }}/wiki/feature/maptools.html). For advanced tools: [ACE3 Equipment]({{ site.baseurl }}/wiki/feature.html).
-`Wind speed (m/s)`: *Two wind speed values (low and high) may be entered on the target screen,[...] Lead/Wind2 button on the screen.* [Horus manual p.32]
- Wind takes into account geographic location, season, time of day and obstacles.
-`Wind Direction (clock)`: *Wind Direction is expressed in clock points.[...], wind is always described in terms of where it is coming from.* [Horus manual p.16]
-`Inclination Angle`: *The degrees field is marked with a “d” and the cosine field with a “c”.* [Horus manual p.33]
- Apply vertical (Page Up and Down keys as default) and horizontal (Left Ctrl + Page Up and Down keys as default) elevations to the [scope]({{ site.baseurl }}/wiki/feature/scopes.html).
- Hold Breath (Left Shift as default) and Fire (Prim. Mouse. Btn. as default).
