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Lapua Blog: Ballistics basics - how to get started

1.9.2017

Lapua Blog: Ballistics basics - how to get started

Lapua Ballistics basics - how to get started

As smartphones and tablets are constantly developed, ballistic software and apps are also improving, and with their help our ability to hit targets can improves significantly. This is a short introduction on why and how to use a ballistic calculator, namely the Lapua Ballistics app, and a few pointers that will help you use the app effectively.

Ballistics software and apps are designed to help shooters and hunters make calculations to hit distant targets or take down game in the field by offering ballistic solutions. Lapua Ballistics is the first app utilizing the 6DOF calculation model.

Toying around with ballistics apps is always fun, but effective use of ballistic software requires general understanding of how they work. The app gets information from the user and by using mathematical formulas it provides the solution that will give the user a solid starting point to hit the target.

However, it is also important to remember that the app can’t think - it only calculates a solution based on your parameters. You will not know the error until you have already fired the shot.

1. SET UP YOUR SCOPE RETICLE AND RIFLE

Scope manufactures use different units per click, so it’s important that you use the correct unit in the app. For example, in your scope, one click can be 0.1 mil or ¼ moa depending on the manufacturer. You can find this information in your scope manual and also usually from the scope turrets. Setting your scope reticle is very important, partly because if you use the wrong unit in the app, the ballistic solution will not match your scope. To set up your scope reticle in Lapua Ballistics, go to Manage Rifle / Cartridge Data --> Add Rifle Cartridge Data (or choose to edit a Rifle/Cartridge combo you've already set up) --> Reticle -->. 

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Another thing to setup in Lapua Ballistics is your scope height, i.e. Line of sight to Bore in the Manage Rifle / Cartridge Data window. This is the distance between the center of the scope and the center of the bore. The default height is 45 mm but with tactical rifles, the height can be even 70mm. So check! The height is easy to measure with a ruler. Then there's also the twist rate of your rifle to set up; look it up in the rifle manual, it can also be stamped on the rifle barrel. The rifle twist rate is needed to calculate spin drift and bullet stability. Spin drift should be taken into account with longer distances, and it can be enabled or disabled in Lapua Ballistics. 

2. SET UP YOUR BULLET CHOICE

You can add your bullet of choice from the bullet library, where you find all Lapua bullets. It is also possible to add information manually. In this case, you will need bullet weight, the ballistic coefficient BC and muzzle velocity.

The Ballistic coefficient can be given in G1 or G7 values. G7 is designed for low drag bullets with a boat tail and G1 is used for more traditional flat base bullets. Lapua on the other hand uses Doppler radar based data to calculate a more accurate ballistic trajectory for Lapua bullets by 6DOF model. Anyway, it is good to remember that the ballistic coefficient changes with velocity, so all changes in a flight path cannot be predicted.

The following thing you will need to set up is the bullet’s actual muzzle velocity. You can reverse engineer the number based on your drop or by using a chronograph. It is good to remember that more rounds you shoot, the better average velocity you will get.

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Because temperature effects muzzle velocity, it would be good to shoot velocities in different temperatures and write them down. Those notes can be used with Lapua Ballistics as it is possible to set up the powder temperature variation in the app.

3. SET UP WEATHER CONDITIONS

Lapua Ballistics has settings for temperature, air pressure and humidity. All these effect the ballistic solution and the chance to hit the target. In a nutshell, temperature affects the powder’s burn speed and in that way the bullet velocity. Air pressure and humidity also affect bullet drag.

If you are shooting approximately on sea level, you do not need to change air pressure values, but if you are shooting or hunting in mountain areas or where there is lot of elevation difference, you might want to check the air pressure. On sea level, the atmospheric pressure is 1013 hPa. The higher you go, the less air pressure you will have and thus less bullet drag. Some like to use handheld weather and wind meters that have a function to get actual air pressure and humidity, however the Get Current Weather function in Lapua Ballistics will give you the air pressure reading from your local and most close weather station, provided that your app is allowed to use your location data.

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Temperature is an important variable. To understand how velocity change in different temperatures, only way is to shoot and keep notes. Some ballistic software and apps have values for muzzle velocity in different temperatures. The user needs to input muzzle velocity in different temperatures in order to software to calculate the effect. More velocities in different temperatures the user adds, the more accurate the calculation will be.

4.  SET UP A BALLISTIC SOLUTION

After we have set up our own rifle / cartridge data, there are few things that need to be taken into account when shooting: the distance to the target, the wind and our shooting skills. Distance can be measured for example with a laser rangefinder and then put in. Wind can also be measured with a wind gauge but it is important to remember that the wind in the target area can be very different from that in the shooting position. Lapua Ballistics gives a ballistic solution based on stationary wind, so in the end, the shooter’s task is to estimate how much the wind factor will be. 

It’s good to remember that Lapua Ballistics is a starting point and designed to assist the shooter. Software and apps have ways of helping us adjust the sight and predict the ballistic solution but they will not replace the shooter. We still have to pull the trigger and record our range data. By keeping good range notes and with the support of good ballistic software like Lapua Ballistics, we should be able hit in all environments.

 

 

Article by Matti Paananen

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