Long range shooting for beginners 7. Data, ballistics and a little maths…

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Your rifle has now been zeroed at 100 yds. If it hasn’t go back to the previous chapters and get it sorted! You could go on forever shooting targets at short range. Some guys do. They take up bench rest shooting and chase small group sizes. Some guys just like to go down to the hundred yard line on a Sunday. Chat to their buddies, fire a few rounds, soak up the atmosphere. Both great fun and perfectly legit. This series of articles details long range target shooting. Varmint and long range hunters may also find some useful info here. To get out of the 100yd rut we need to do some geeky stuff. I promise to keep it relatively simple. Make no mistake though, getting hits at a calibres near maximum range needs a little bit of brain power and a patient methodical approach.

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If my maths were off then hits at steep angles would prove impossible..

Data

As mentioned in the previous instalment, keeping records of data is vital for the following process. If you didn’t write anything down then go back to the range and repeat your load testing and this time keep the data. If you have access to a chronograph then now would be a good time to use it. A Chrono will tell you how fast the bullets are travelling when they leave your barrel. If you don’t have access to a Chrono, don’t fret, for a basic “get you on paper” ballistic table we can take an informed guess at velocity later on. To move to the next stage you should have now selected the ammunition that provided the tightest group. Don’t forget this guide is for the beginner. The tightest group isn’t going to be the only factor in deciding which ammunition is best but for now we want to keep things simple. Our aim is to get out to 1000+yds on a limited budget and limited experience..

The flight of a bullet

So what do we do with this vital data? Well we can use it to build a ballistics table. In simple terms a table will tell you how many clicks on the elevation turret need to be dialled to hit a target at any sensible distance.
When a bullet leaves the end of your barrel it flies toward the target (hopefully). Most people believe bullets travel so fast they go in a straight line (flat trajectory). In reality the bullet is being pulled down by gravity the same as anything else on this planet. The faster the bullet travels the less it seems to be pulled down but it is still occurring. The bullet therefore travels in a curve not a straight line as shown in the diagram below.

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When you click your elevation turret “up” the reticle moves which causes you to elevate the barrel a tiny amount so as to centre the reticle on the target. As you increase barrel elevation your range increases, obviously. Using our limited data to build an approximate table Involves using maths to predict these curves. If they can be accurately predicted you can hit targets at any distance using the prescribed number of clicks. The same thing can be done with windage although that is a little more difficult to predict..

MOAs and Mils

Each click on your scopes turrets represents an exact measurement. They must be exact. If you dial in good data and the scope is off then you will really struggle at mixed distances. The measurements tend to be in either MOA minutes of angle or Mils, short for Milliradians. Both of these are measurements of angle. Imagine two lines running into the distance with one at a slight angle. As you move further forward the distance between the lines changes as they get further apart. If the lines were set at an angle of 1moa then at 100yards they would be approximately 1 inch apart. At 200yds 2 inches, 300yds 3 inches and so on. mils give a coarser level of adjustment, 1 mil equates to approximately 3.6″ at 100yds. Remember again as range increases so will the actual distance between the two theoretical lines. At 1000yds a mil works out to be about 6 feet.
If you look on your scopes turrets they will be marked telling you what each click equates to. MOA scopes will generally be 1 click = .25moa. Mil scopes tend to be 1 click = .10mil.

The good news is that you only need a basic idea of the above to be able to shoot. Is you scope in MOA or Mil clicks? That is all we really need to know for now. Later articles will look into ballistics and deeper concepts. For now we deal with some basics as it can be a lot to try and take in.

Ballistic programs and apps

There are two ways to build a ballistic table. The simple but time consuming route would be to zero the rifle at 100yd increments out to maximum range. Record how many clicks you had to dial in to get the bullet hitting centre at each point. It is a reliable way of doing it but it can be time consuming and not always possible to do at a civilian range.
The second way is to cheat and use technology! Yes!!
There are a number of FREE ballistics apps available as well as many paid versions. I use a paid version of Strelok for Android. I bought the pro version for a few pounds. There are others available on Android, IPhone, PC ect. The JBM ballistics page is well worth a look. Several types of ballistics calculators are available there.. http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

This is where your data becomes vital. If you input the correct data, any of these calculators will give you a reasonably reliable table that you can print out and take to the range. If you input the wrong data or you try to guess it all then the tables will not be reliable… Totally useless in shooting terms.
Most calculators will ask for a lot of data. Be prepared! They will want weather conditions on your 100yd zero day and the conditions when you shoot again. Info on your rifle will be required, barrel twist and so forth. The bulk of the info will be data on the bullet itself. There are several ways to get the data. You can often find it online at the manufacturers website. You can take measurements yourself if you have the ammunition and micrometer/scales (tricky to do accurately and some inputs such as BC cannot be measured physically). Last option would be to buy a reloading manual. I highly recommend the first and last options. Leave the accurate measurements and complex math to someone else. I mention BC above. This refers to Ballistic Coefficient. In simple terms it is a number which denotes a bullets performance in terms of drag. Most ballistics apps require BCs and various other info which can be tough to find if your bullet choice is a less popular type. I bought a fantastic book by Brian Litz called Applied Ballistics for Long range shooting. It isn’t cheap but it is superb and invaluable in data terms.

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The main screen of Strelok Pro

The only piece of data you might struggle with is muzzle velocity. If you have Chronograph results for it then great, if not don’t fret. If you selected a common calibre such as .308 you will find 1000s of posts online. If you selected a popular rifle such as a Remington 700 you will find posts relating to muzzle velocities from the same rifle in the same calibre using the same or similar bullet weights. Now your seeing the benefits of selecting tried and tested kit. The data already exists. Try and find a few examples of velocities measured from your chosen rifle and take an average from them. Use that average velocity in your ballistics data input. It won’t be perfect but its the best way without a chronograph.
After all that tedious data input we can now get to the interesting bit. Select a distance to target which is above your zero range (I.e. greater than 100yds if your following this guide!). Select calculate (you may need to make some average weather inputs here if your sat at home. The calculator will then let you know how many clicks of elevation you would need to dial in the hit the target at your chosen distance. It will most likely let you know a bunch of other cool info as well such as flight time, energy, windage, and a choice of inches, moa or mils for your readouts.
Strelok allows me to build custom tables and save them. I can then email them to my PC and print them off. I can then take them as hard copies when I go to the range. You can’t always count on technology working… If your calculator won’t build tables for you then just draw a table out and fill in the info. I would draw it from 100yds to 1200yds in 50yd increments.

We are now ready to make a trip to the range and shoot at greater distances. That is the whole point of this series of articles. We want to aim for 300yds, 600yds, 900yds, 1000yds, 1200yds+
Not everybody has direct access to ranges which can accommodate those distances. You may find you have to travel. Check out where you can shoot at long range and I’ll start writing the next article in this series.
Be safe.

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