Tutorial

Here you'll find a full walkthrough of Weta Precision, along with some tips and information.

I'll update it and add to the FAQ as I receive feedback.

Location Information

When you first run Weta Precision, you will be asked to allow access to your location. We use the OpenWeather online service to retrieve environmental information in your area, and for this to work Weta Precision requires access to your location.

We do not save your location, or use background location data.

Where to Start

Click the menu icon at the top left to open the drawer. Here you'll see a list of your rifles and bullets - we've started you off with one of each.

You can edit their details by clicking the pencil icon to their right.

Settings

However, as different countries and people prefer varying combinations of units, you may like to get started by clicking Settings and choose your preferences.

Edit Rifle

Next, edit the sample rifle by clicking the pencil icon as described above.

I find it useful to enter my serial number here as I'm required to provide it at one of my shooting ranges.

The rifle type (rimfire, centrefire) is purely to set a maximum distance in the calculator screen.

Save Rifle

Remember to set your scope height - this is the distance from the centre of the barrel to the centre of the scope, measured in the middle of the scope.

To do this, measure the barrel diameter and halve it. Measure the scope diameter and halve it. Finally measure the distance between them and add all three numbers together.

You should also select your turret type and click Save once you've finished.

Select Rifle

The item will update with your new details. When selected, it will be highlighted as shown above.

If you have already selected a rifle before editing it, there is no need to select it again after editing - the changes will take effect immediately.

You can add as many rifles as you like. Just click "Add New Entry" under Rifles. Once added, they will be selected - new bullets are always added to the selected rifle.

Edit Bullet

Once you've selected your rifle, the list of Bullets will display the bullets you've added to it.

You can add multiple bullets to a rifle by clicking the Add New Entry row.

Edit the sample by clicking the pencil icon, just as you did for the rifle.

Save Bullet

Overtype the text with your own details remembering to select the correct drag model (G1, G7 etc) for the information you have available.

The entries under Spin Drift are only required if you want spin drift to be calculated for you. You can often find the bullet head length online.

I'm working on allowing multiple BCs per bullet, so check back for updates!

Select Bullet

Your changes will be reflected in the Bullets card right away.

Select it and slide the drawer away to get back to the main screen.

You can add as many bullets to the rifle as you like. Just click "Add New Entry" under Bullets when you have a selected Rifle.

Weather

Your environmental conditions have enormous impact on bullet performance and trajectory.

Tap the top right location icon to see your current conditions as determined by the OpenWeather service.

min and max refer to the predicted minimum and maximum temperature in your location.

We also fetch your what3words as Emergency Services are increasingly able to use them to locate you.

Override

You can override the forecasted humidity and air pressure (both very important for accurate calculations) by tapping that area of the screen.

Make your changes then click Confirm to save them. Your air pressure will be set in the unit you chose in Settings:

  • Inch of mercury (inHg)

  • Hectopascal / Millibar (hPa)

Temperature

You can fine tune the temperature to your exact location by sliding the display up and down, overriding the forecasted weather.

When overriding, the temperature, min, max & feels like will all read the same value, and are not used in any calculations.

Navigate back to the calculator...

The Calculator

Set the Range

The calculator screen is broken down into cards such as WIND and RANGE. Each one has its own purpose: Some display information and others allow input of data.

Set the distance in the RANGE card by sliding the indicator. You can fine tune it by clicking - and +. The distance is shown between them in the units you chose in Settings. A long press (1+ seconds) on the distance button will pop up a dial, but more on that later.

The highlighted bar shows the distance past your zero range. Here we have zero set at 100 yards and the distance is 600 yards.

As you change the distance, the drop is calculated automatically and updates the ELEV and WIND cards.

The ELEV card shows us that our bullet will drop more than 8 feet so we need to adjust our .1 Mil scope (1/10th milliradian) UP 47 clicks.

Set the Wind

Specify the direction the wind is coming from in the WIND card by sliding the dial to the appropriate position.

This assumes you are facing your target.

Next, specify its strength by spinning the wind speed meter inside the direction dial.

Here we've chosen a 5mph wind coming towards us, slightly from the left. You'll see that the WIND card has updated itself to show that the bullet will veer more than a foot to the right, so we need to adjust 6 clicks LEFT in our milliradian scope.

You'll also notice the lowermost card updating with the time taken to reach the target, final mach number and speed.

Hit RESET to return the dial to the top and wind strength to 0.

Shooting Angle - Tracking

Angle

The ANGLE card allows you to set your shooting angle (up/down).

By default it assumes you are on a level surface: 0 deg.

Double Tap

The ANGLE card can detect your angle.

To do this, double tap it. It will use your phone's accelerometer to detect the angle.

On a flat level surface, it should read 0.

Single Tap

Set your phone on your turret or barrel to detect the angle, then single tap it to set the angle.

You can slide the indicator to manually set the angle.

Hit RESET to set it back to 0.

Pull-down Details Card

The top most 'Details' card displays the make and model of your selected rifle and bullet.

Slide it down to reveal additional information, including your rifle's serial number if you filled it in while editing.

All details are only ever stored on your device.

Extra Distance

If you need to push further than the range slider will allow, hold down the range button for at least 1 second. When you release, a popup will allow you to dial in a longer distance.

Click Confirm to update the calculator.

New Calculation

The new trajectory will be calculated and the range button updated with the furthest your bullet will travel before it loses too much energy.

Here, my .308 load will only realistically reach 1700 yards, though not accurately!

Trajectory Table - Zero

No ballistics app would be complete without a trajectory table showing your drops! To display it, tap the table icon at the top right, next to the Location button.

The table can be scrolled in all directions and displays the mach number, energy and time to distances in increments of 100 for centrefires, and 10 for rimfires.

Your zero range will be highlighted in blue.

Trajectory Table - Transonic

You can see the Energy and Velocity dropping rapidly here.

The calculator adds an extra entry for your transonic point, and highlight it in red.

I'm working on allowing you to export this, so check back for updates!