Basic rules and how to work with a sniper rifle
PANAGYURISHTE, (BM) – It may seem that the riflescope is parallel to the barrel to the naked eye, but this is not the case. The barrel axis and the optical axis of the sight form an angle called the aiming angle. And the trajectory of the bullet, of course, is not straight, and the target is not always on the same level with the rifle – often, you have to shoot with significant elevation or depression angles. In-flight, the bullet is affected by gravity and various aerodynamic forces that must be taken into account when aiming.
To maximize high-precision sniper rifles’ capabilities, ammunition with increased accuracy, the so-called match-class cartridges, is required. They are manufacturing precision equipment with minimal tolerances. Particular attention should be paid to the design of the bullet. A tapered tail section distinguishes it in the form of a “boat stern” and a cavity not filled with lead in the shell’s bow.
The effect of gravity on the flight of a bullet is quite simple to estimate. For a particular time (or at a certain distance), the bullet decreases. Depending on the firing distance, this decrease can be calculated using a ballistic calculator or using tables and then corrected using the sight’s appropriate flywheel. As a rule, flywheels are graduating in the corners. In the West, minutes of angle (MOA) is taken. In Russia – thousandths of the distance, or milliradians (transverse dimension of 1 m at a length of 1000 m, one mrad = 3.43 MOA) … To facilitate the task, flywheels sometimes calibrate in meters of distance (such an amendment will work for specific ammunition in standard conditions).
Correct distance determination is significant for accurate shooting. There are many techniques for this – from using a laser rangefinder or comparing an aiming reticle with known object sizes to basic signs such as “the movements of a person’s arms and legs are distinguishable from 500-600 m”. Several situations make it difficult to determine the distance visually correctly. The greater the firing distance, the more the error in determining the length will affect the final result – the possibility of hitting the target.
Air resistance slows down a flying bullet. That effect must consider when calculating corrections (especially in non-standard situations – for example, in mountainous terrain, when the air is rarefied). Humidity and air temperature also affect. But much more critical is the aerodynamic sidewind drift. The fact is that when firing at long distances (several hundred meters) along the trajectory of the bullet, the wind can change several times – both in strength and direction. High-rise buildings create powerful air currents in the city, which seriously impede police snipers’ work during special operations. The wind’s speed and order must be determined by fluctuations in the ascending air currents – mirages – or even predicted altogether. The sniper proverb says: “Beginners learn ballistic tables, and seasoned snipers learn the wind.”
When breathing, it is essential not to disturb the stability of the rifle. Therefore, it is correct to execute a shot on exhalation, with empty lungs, when the sniper can “freeze” for a few seconds. To extend the pause between breaths, the shooter must take two deep breaths before firing to saturate the blood with oxygen. However, when seconds count down, the sniper may not have enough time to take two deep breaths. Then the technique of “freezing” is applied – with lungs, half or three-quarters full.
The point of gravity applied to the bullet (center of mass) does not coincide with using aerodynamic forces (center of pressure, located in front of the center of mass). As a result of these forces, and overturning moment arises in the plane of the trajectory. But since the bullet rotates and is a gyroscope, its axis of rotation is deflected perpendicular to the plane. That is, if the bullet turns to the right, a deviation to the right occurs, and precession occurs – oscillations of the bullet’s axis of rotation. This precession axis will be deflected to the right, and aerodynamic forces deflect the bullet’s flight in the same direction. This phenomenon is called a derivation. It depends on the bullet’s speed and the speed of its rotation, mass, and shape. Usually, this effect begins to affect the accuracy of shooting only at sufficiently large distances (where it is likely to “get lost” against the background of much more significant drift).
Since the bullet rotates in flight, in a crosswind, it can be influenced by the Magnus effect – when the airflow around a rotating body, a force acts on the body, directed perpendicular to the flow. On the bullet side, where the direction of rotation coincides with the flow stream’s path, the airspeed increases; on the other, it decreases. The pressure difference generates a force directed to the side, where the direction of rotation and the airflow direction coincide. The effect of Magnus has no noticeable impact on the practical results of the shooting. Therefore it is usually neglected.
1. The barrel must not come into contact with anything! 2. Press the trigger with the most sensitive part of the forefinger pad. 3. To set the position of the stock, put a bag of sand under the butt. By pressing on it with a hand free from shooting, you can make a slight height adjustment. 4. The distance between the eye and the eyepiece should be precisely maintained so that the entire visual field can be seen entirely and without distortion. Usually, this value is 7-10 cm. 5. If time permits, it is necessary to secure the rifle’s position with a belt. 6. Do not allow the weapon to fall. 7. It is better to use a bag of sand instead of a regular bipod as a stop.
Up and down
As a separate case, it is worth considering shooting corrected for the target elevation angle. This situation occurs in the mountains or in the city, where snipers set up positions on buildings’ roofs. When shooting at a target located above or below the shooter, it is imperative to make an adjustment that depends on the elevation angle but does not depend on whether it is a positive or negative angle – in both cases, when the usual correction is introduced, the bullet will pass above the target. Shooting at an angle to the horizon requires less discipline than usual. The fact is that the absolute decrease in the bullet trajectory to the barrel line is always considering perpendicular to the horizon, and the relative decline is steep to the line of sight.
Gravity affects a flying bullet in the same way as any falling object. During the flight, the bullet is significantly reduced, which can lead to a miss. The drop can be calculated from tables or using a ballistic calculator, but the distance must be accurately determined.
Through the glass
Quite often, police snipers have to deal with a situation when a terrorist who has taken hostages is behind a transparent barrier – glass. You can aim at it, but can you hit it? It would seem that glass is a fragile material, but it can significantly affect the shooting result. On this score, snipers have several considerations:
- It all depends on the thickness and material of the glass.
- It would be best if you did not use expansive bullets, which tend to change trajectory unpredictably when passing through substantial obstacles.
- A shot perpendicular to the glass has less effect on the course of the bullet.
Certain types of glass produce many sharp fragments that can harm the terrorist and the hostages. A method is often used when one of the police snipers breaks the glass with a shot, and his colleagues hit the target without a pause.
How to shoot?
The cartridge properties and the bullet mean no less in the sniper business than the advantages of the barrel or sight. Therefore, speaking of high-precision small arms, we suggest the “rifle-ammunition” system. There are many sniper ammunition varieties, ranging in caliber, cartridge length, bullet design, and powder charge characteristics, but the real workhorse is the .308 Winchester cartridge, also known as 7.62 NATO. These are match-class cartridges manufactured on precision equipment with minimal tolerances. The bullets used in this type of ammunition are designating by the English abbreviation BTHP (Boat-Tail Hollow Point).
There are several situations where a visual determination of distance can give an error even with a trained eye. In some cases, objects may appear closer: in a lowland hidden behind hills, when viewed from top to bottom, along with long, straight landmarks such as rails, or against a uniform contrasting background such as snow or sand. In other cases, objects may seem farther than they are located: against the set of large items and structures, when looking upward, in a narrow space, or a visible lowland.
The term boat-tail refers to the characteristic tapered tail of a bullet.
The tail cone reduces the top part of the bullet, improving its aerodynamic characteristics, reducing the loss of speed, and increasing the resistance to side wind. The bullet also has a hollow point – this enhances the lethality. 168-grain .308 Winchester sniper cartridges with a BTHP bullet are produced by Remington, Hornady, Lapua, Norma, Federal, and others. The sniper business also uses .223, .300, and even half-inch .50 caliber cartridges (for large-caliber rifles).
Follow us everywhere and at any time. BulgarianMilitary.com has responsive design and you can open the page from any computer, mobile devices or web browsers. For more up-to-date news from us, follow our YouTube, Reddit, LinkedIn, Twitter and Facebook pages. Do not miss the chance to subscribe to our newsletter. Subscribe and read our stories in News360App in AppStore or GooglePlay or in FeedlyApp in AppStore or GooglePlay
Subscribe to Google News