Bullets are different. Their type depends on the weapon for which they are made. There are shells for smooth-bore weapons, rifled, pneumatic. Accordingly, they look different. The size will be determined by the type and size of the weapon.
There are large live ammunition, large bullets or very small for pistols and revolvers.
However, the speed of a bullet will be determined not only by its size. Many other factors influence it.
Factors Affecting Bullet Speed
A number of reasons can slow the initial velocity of a projectile when fired from a weapon. Consider the main ones.
- Ambient temperature. The lower the air temperature, the more energy is spent on heating the gunpowder and the projectile, that is, the initial departure speed is reduced.
- Humidity of gunpowder. The drier the gunpowder, the higher the initial speed will be, as the pressure in the barrel of the weapon will increase.
- The shape and size of powder grains. The finer the dispersed particles of the powder charge, the faster they will burn. Consequently, the initial velocity of a bullet shot will increase .
- Gunpowder charge density. In order to maximally correctly and safely charge a product with gunpowder, special accurate engineering calculations are necessary. Without them, an overdose in gunpowder is possible, which will lead to internal detonation of the weapon. Or, on the contrary, undercharging, which will lead to overheating of the gun barrel. It is forbidden to independently reload the powder component in the weapon!
- The length of the barrel of the weapon. The shorter the barrel, the less time the action of powder gases takes place, which reduces the speed of the bullet.
- Product weight. The lighter the bullet by mass, the higher its initial velocity.
Each of these factors may vary slightly depending on a particular type of weapon. However, in general, it is these conditions that affect the initial and total velocity of a bullet during a shot.
What is a chronograph?
The chronograph is a special device that allows you to track some indicators of the internal and external device of the projectile and, based on the data obtained, conclude its possible speed.
The device is designed in such a way that with its help you can easily check the declared technical characteristics of the weapon in the store. In addition, it determines the initial and total speed of the bullet.
Using a chronograph, you can see and evaluate the following weapons indicators:
- cylindrical pressure (its level);
- spring fatigue or barrel lead;
- the device will show the mass of the cartridge;
- will give an assessment of quality;
- will show worn piston cuffs;
- temperature.
An electronic device by calculation and generalization will give a real result for all indicators. However, it has its drawbacks.
Chronograph Disadvantages
The device has a certain weight and size, which makes it not always convenient to use in certain conditions (for example, field conditions). Also a disadvantage of this device is the measurement error (electronic). It is not too significant, but it still has a place to be.
The device counter is triggered and stopped depending on the illumination of the terrain (room), which also forms a certain error in the readings.
Such a device will not reliably show the exact real trajectory of the bullet’s movement , for this a different measurement method should be used.
Backache of various distances
This is a more accurate and realistic way by which you can determine the speed of a bullet. To do this, you will need not only attentiveness, but also a computer with an installed ballistic calculator, which will give complete information and the most accurate calculations.
The work goes as follows:
- load the necessary data into the ballistic calculator, which we take from the manufacturer of the weapon and from our own indicators (we shoot the weapon at 100 m to zero);
- enter the mass of the cartridge, the shooting distance;
- measure and load the height of the sight over the barrel of the weapon;
- from the manufacturer we take data on vertical and horizontal clicks in optics;
- we make readings of temperature and air pressure at the time of the study (the more accurate, the more real and better the result will be);
- height indicator above sea level;
- bullet speed from the manufacturer.
In the calculator there will be graphs of lumbago distances. We indicate 200, 300, 500 and 700 meters there. Longer distances are not immediately recommended. In the columns where 1 MOA is requested, we write the following values according to the order of distances: 5.8; 8.7; 14.5; 20.3 centimeters.
All other work consists only in clicking the mouse on the calculator. Follow the navigator on the ballistic device and as a result you will get an accurate and real indicator of what is the speed of the bullet.
Some values of cartridge speed of different calibers for the machine
As mentioned above, it is difficult to give an accurate assessment of such an indicator as speed. In many ways, it is determined by environmental circumstances. However, approximate values for machine guns of various calibers can be given.
Studies and calculations showed that the value of the cartridge’s flight speed from the machine will depend on its model and caliber, so variations in the data given are possible. But these errors are small, and everyone can fix them for their weapons.
Automatic machine AK-74 caliber 5.45X39
If shooting is done with a normal (normal) cartridge, then the average data on the speed of the bullet will show a result of about 870 m / s. If the distance is approximately 500 meters, then the speed will decrease to 428 m / s.
This type of weapon has an elongated barrel, so the bullet speed is quite high.
AKS-74U caliber 5.45X39 and AK-101
If we talk about the speed of the fired bullet from the AKS-74U with a caliber of 5.45X39, then it will be approximately 740 m / s. Smaller than the previous one, because the trunk is shorter.
The AK-101 caliber 5.56X45, on the contrary, will show a very good result in this regard. Approximately 930 m / s, thanks to the long-barreled weapon structure. The American analogue of this weapon has an even longer barrel length, for both types of machine guns the same cartridges with such a value of the initial velocity of the shot are suitable.
AK-47 assault rifle
The shells of this weapon have a larger mass than all AK followers, therefore they have powerful penetrative power. However, they are inferior in speed to their colleagues, because it is only 740 m / s. Nevertheless, this is quite enough for this machine gun to be considered a formidable and serious military weapon.
Muzzle bullet energy
In addition to speed, a very important characteristic is also the energy of the bullet. To calculate the muzzle energy, it is worth recalling the usual school physics course. The simplest formula will be: (mass x speed) 2/2 , (mass in kilograms, speed in meters per second).
Why is the value of cartridge energy important? Because energy is the power of a bullet, its main combat characteristic. The larger the mass and the higher the speed, the higher the energy, respectively. So, the weapon itself is more powerful and long-range.
In other words, this is the usual formula for calculating the kinetic energy of a body. The maximum muzzle energy is possessed by rifle bullets. They balance the mass and the initial velocity of the bullet in such a way that the work is powerful and efficient.
For example, at a distance of about 100 meters, the depth of entry of a rifle bullet into sufficiently dense materials is from 0.6 to 350 cm. These are materials such as steel plate, wood, iron plate, a layer of soft clay, gravel or crushed stone, brickwork, earth or rammed snow. These data are based on a study of the muzzle energy of the lungs by the mass of bullets.
Obviously, the value of the velocity and muzzle energy of any projectile is very large and determines the power and range of the weapon.
Airguns
Not so long ago, a survey was conducted among the owners of pneumatics on the topic: "What is the speed of a bullet in your air gun? Interestingly, the percentage variation in speed is very variable.
So, for example, most of the respondents (20%) cited the figure of 220-305 m / s. Since this, in principle, is a normal average indicator for pneumatics, the figure does not cause mistrust.
However, almost 9% of respondents claim that their weapons have a bullet speed of 380 m / s or more. This figure makes one doubt its reliability. Some kind of too powerful military weapon is obtained. Such a value for the speed of a bullet for pneumatics is rare, not every model can boast so.
According to 19% of the participants, their weapons hit at a speed of 100-130 m / s and 130-180 m / s. At 11%, this figure tends to 350 m / s, which is quite serious. And finally, 6% of the participants estimate the bullet departure speed in their pneumatics at 75-100 m / s.
Most often and easier to measure the speed on airguns using chronometers. Most of these devices are designed just for pneumatics. Although the measurement error will not go anywhere, but the result will still remain fairly reliable.
No matter how you measure the speed of a bullet flying out of your weapon, the error will still not go away, since the external environment will always be different in its indicators.