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](https://ace3mod.com/wiki/feature/rangecard.html) and check the cartridge, the zeroed distance, the rifle twist, the muzzle velocity at 15°C and the bore height.
- Open the AtragMx and the `Atmsphr` column, select `Default` and `Done`. [[Manual]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=15)
-`Open Gun` the 7.62x51mm M80 in the `GunList`. [[Manual]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=25)
- Select `E` (English unit) at the top right. [[Manual]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=10)
- Open the `Gun` column, check and update the `Bore`, the `Rifle Twist` and `Done`.
- Select `M` (Metric unit) at the top right.
- Open the `Gun` column, check and update the `Muzzle Velocity`, the `Zero Range` and `Done`.
- *The Muzzle Velocity Table will be automatically updated.* [[Manual]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=22)
- *(Must be edited manually for specific cartridges according with the range card)*
- Optionally, `Save Gun` and `Done` in the `GunList`.
- Update the `Target` column (the [wind arrow](https://ace3mod.com/wiki/feature/weather.html) will also help). [[1]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=16) [[2]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=30) [[3]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=32) [[4]](https://horusvision.com/download/manual_Horus_ATrag-v385.pdf#page=33)
- The `Default zero distance` can be overwritten with the [Scopes module](https://ace3mod.com/wiki/feature/scopes.html) or the [Settings Framework](https://ace3mod.com/wiki/framework/settings-framework.html).
- In this case, the [Range Card](https://ace3mod.com/wiki/feature/rangecard.html) will be automatically updated, NOT the AtragMx.