We are kicking off a brand new series on our website: Lapua Ballistics app tips! Get the most out of our free of charge ballistics calculator by following our tips which we will be sharing all through year 2020. The first tips are:
Utilizing Point Blank Range and V0 or Muzzle velocity calculation. The next tip will be the Sight-In POI feature, followed by benefits of 6 DOF calculation.
EASY APP SETUP: If you haven’t tried our app yet, download it and check out our guide for easy setup!
TIP: Utilizing Point Blank Range
The Point Blank Range (PBR) feature shows the min to max distance within which the bullet will hit the predefined target area without adjusting the point of aim or scope. Knowing the PBR is useful in situations where you don’t have time to make adjustments to your scope or you don’t know the exact shooting distance – a typical situation when hunting. By calculating the PBR you can optimize your sight-in distance so that the PBR is as long as possible. We will also explain how you can “set” your scope for a distance of e.g. 170 m , even if you only have a 100 m shooting range.
How to use the Point Blank Range feature in Lapua Ballistics:
- Choose your cartridge and set correct muzzle velocity and barrel twist.
- Important – make sure you have entered the correct “Line of Sight to Bore”. Line of Sight to Bore refers to the distance between center of the bore to the optical axis of the scope.
- Weather conditions don’t have significant impact on this feature. Insert the typical temperature, air pressure and humidity for your hunting area.
- Define the target hit area size in relation to the point of aim (the perfect hit), i.e. enter the height of the pipe within which the trajectory should be.
- By comparing (i.e. bracketing) values, you can optimize sight-in distance by changing it to the distance within which the bullet stays within the pipe you have entered.
- In practice, you want a sight-in distance where the highest point of the flight path touches on the top of the pipe you entered.
EXAMPLE: PBR for big game hunting cartridge
In this example, the shooter wants the bullet to hit the target (+/- 5 cm) within a 10 cm window size. If the rifle is sighted in at a distance of 100 m, the shooting distance range is 0 to 160 m without adjusting the scope or changing the point of aim.
By bracketing, the optimum sight-in distance is found to be 170 m, with the shooting distance range of 0 – 200 m without adjusting the scope of changing the point of aim. The Elevation LOS column in the flight path table (below) indicates the elevation height of the bullet in relation to the line of sight.
Utilizing the flight path table
Error calculation / unstable bullet
TIP: Muzzle velocity calculation
Most ballistics programs require the muzzle velocity V (at 0 m/yds) of the bullet as the starting value for ballistic calculation. However, most chronographs have to be installed several meters/yards in front of the barrel muzzle so that the muzzle pressure and muzzle flame do not interfere with the result or damage the chronograph. With the muzzle velocity calculation function, the bullet velocity V measured at a distance of x meters/yards can be converted to the bullet velocity V at the muzzle of the barrel (at 0 m/yds). The function is only intended for short distances, less than (or maximum) 25 m/yds.
Using the function:
- Enter the editing mode of the cartridge you are using (pen image).
- Activate the Powder dv/dT Visible button
- Activate the Velocity V1 Visible button
- Enter the distance from the barrel muzzle to the chronograph in the Range window (unit m or yd; here 10 m) and the velocity reading by the chronograph in the V1 window (unit m/s or fps; here 730 m/s).
- The muzzle velocity of the bullet is shown in the V0 window (unit m/s or fps; here 736 m/s).