Long distance shooting: Strelok PRO an essential application

Author: Jérémy COMPIEGNE

The TLD is becoming more and more fashionable in France and the phenomenon is likely to gain even more speed in the coming years . Many people start the TLD every year, the configuration of a ballistic calculator is an inevitable step but which is often not done with the seriousness that this step deserves. In this article we will break down the configuration of the STRELOK PRO calculator. This application is no longer available on Android and iPhone for reasons of ban and the war in Ukraine, the images presented here are taken from the Android application, there may sometimes be some differences with the iPhone version.

This article explains the importance of each element and can be duplicated to any ballistic calculator whose functionality is identical, only the user interface changes.

The goal of this article is to understand the importance of each of the data entered and not to forget anything! This method is broken down into 5 steps, the first 3 are to be done only once per weapon. The last two will be done for each shooting outing because the conditions are never strictly the same.

There is only one thing to keep in mind regarding ballistic calculators in general: The accuracy of the output data will depend 100% on the input data!

Good entries = Good exits / False entries = False exits

Step 1: Configure the data related to the scope

1.1 Setting distance (distance at which you have currently zeroed your scope). Zeroing consists of aiming point = point hit at a certain distance with the elevation turret at zero. Generally for the TLD we choose a zeroing at 100m.

1.2 The height of the scope , this height is very important to calculate the convergence of the barrel-scope axis. This height is the barrel-scope center distance and not the space separating your barrel from your lens

1.3 The value of your clicks , generally either 0.1 (for 0.1 mrad scopes) or 0.25 (for ¼ MOA scopes), some scopes have uncommon values ​​that can still be entered here (1/8 MOA or 0.2 mrad etc…)

1.4 Selecting your scope units either mrad or MOA (always written on your scope turrets, sometimes you will see mil, mil=mrad in the USA.

1.5 Selecting the reticle will help you in case of counter-aiming, strelok has a very interesting menu on this point, you will find the name of your reticle on the documents of your scope

1.6 Finally the application asks you to choose whether your reticle is at the first focal plane (FFP First Focal Plan) or at the second focal plane (SFP second Focal Plan). If your reticle is at the second focal plane the application will need to know your reference magnification which is generally materialized by a point on the magnification adjustment wheel , for example here the reference magnification is at 11

Step 2: Configuring ammunition-related data

Step 3: Configuring weapon-related data

3.1)  The rifling pitch in inches , the latter is used for two things: to calculate the gyroscopic drift and to give you a gyroscopic stability index . Concerning the gyroscopic drift even without wind your projectile due to its rotation will deviate laterally. The faster the bullet turns on itself and the more this drift is important, the rotation speed depending on the rifling pitch it is important to inform it correctly.

Regarding the gyroscopic stability index:

- A value less than 1: the bullet will not be stabilized in your barrel.

- A value between 1 and 1.5: marginal stability, risk of lack of stability under certain weather conditions

- A value greater than 1.5: good stability in most situations.

Be careful, however, this stability calculation tends not to strictly correspond to reality in the case of using a very tapered projectile.

3.2) No rifling on the left or right, 99% of barrels have a rifling pitch on the right, it is unlikely that you are in the case of a barrel with a pitch on the left. It is important to know the direction of rotation of the bullet, in fact if the pitch is on the right the bullet will have a gyroscopic drift to the right, conversely if the rifling pitch is on the left the gyroscopic drift will be to the left.

Step 4: Geographic and wind intelligence before shooting

4.1) Target distance , be aware that an error of a few meters at large distances can lead to significant errors. For this, either GPS data or a quality rangefinder is used.

4.2) the angle between the horizontal and the target , this angle is important when shooting at significant relief (mountain or cliff), when the angle is less than a few degrees it has no importance.

4.3) The wind speed in absolute terms, for this an anemometer will be the essential tool! But be careful, it measures the wind at the shooter's level which will not necessarily be the winds 100 or 500 meters further. For this, experience and practice will allow you to better understand the evaluation of the wind. (As our cousins ​​across the Atlantic say: "Elevation is science windage is experience")

4.4) The direction of the wind , the angle of incidence of the wind will have a different impact depending on its origin. To do this, head towards the target, if the wind comes from the target towards you then you have a wind at noon 12 o'clock or 0°, if it comes from your left a wind at 9 o'clock or -90°. For the curious: the calculator breaks down the wind into two components (like a vector). The component perpendicular to your trajectory is the most important, however a strong headwind or at 6 o'clock can make you impact high or low, in fact the ball no longer brakes in the same way because its speed relative to the air is no longer the same.

4.5) The Coriolis effect , This effect comes from the fact that the earth rotates on itself and that during the flight of the bullet the target will have moved. This phenomenon is only to be taken into account in the case of shooting more than 1000m upstream, the Coriolis effect is almost insignificant.

Step 5: Weather information before shooting

5.1) The outside temperature must be filled in accurately, the application needs this data to calculate the air density, the higher the temperature the lower the density and therefore the less the ball decelerates.

5.2) Atmospheric pressure in hPa, this data is also used to calculate the air density, the higher the Atm pressure, the higher the air density and the faster the bullet will be slowed down. (It is better to shoot in the mountains than at the seaside when it comes to shooting very far)

5.3) Humidity has a very slight influence on air density, it is the least important weather parameter in calculating air density.

5.4) The temperature of the powder is only used if when entering your speed you entered speeds at several temperatures, in fact a munition will not start at the same speed between 0°C and 25°C. Combustion is a chemical reaction whose starting temperature is a factor influencing the combustion speed.

Last step: Start the calculation and understand the application outputs

Once you have completed the 5 steps, all you have to do is start the calculation using the " Calculate!" button and the application will determine what correction you need to make in order to hit the mark!

The first data line contains the information about the vertical plane (projectile fall) expressed in MOA, MRAD, cm and clicks. The letter U in front of the values ​​corresponds to Up to say Climb.

The second data line contains the information about the horizontal plane (projectile drift) Expressed in MOA, MRAD, cm and clicks. The letter L in front of the values ​​corresponds to Left, which means that the projectile must be sent to the left because of the firing conditions.

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Kind regards,

Jeremy