The Kalashnikov assault rifle is a legendary weapon, known throughout the world for its reliability and simplicity. But when it comes to bullet speed, many are faced with conflicting data. Some sources talk about 700 m/s, others - about 900 m/s, and still others even give figures depending on the modification and shooting conditions. Why such a spread? The fact is that the speed of a bullet from an AK depends on many factors: cartridge caliber, trunk length, air temperature and even altitude above sea level.
In this article we will figure out how exactly the bullet speed is formed, compare the indicators for different modifications of the AK (from AK-47 up to AK-12), and also answer questions that often arise from gun owners, hunters and simply curious readers. You will learn why the speed of a bullet is not equal to the speed of sound, how it is measured, and what happens to the bullet after it is fired.
Important: the article is for informational purposes only. All manipulations with weapons must be carried out in accordance with the laws of your country and safety regulations.
The physics of a shot: how a bullet picks up speed
The speed of the bullet is formed in the first fractions of a second after pressing the trigger. When the firing pin strikes the primer of the cartridge, the powder charge is ignited. The gases formed during the combustion of gunpowder create enormous pressure (up to 3000–4000 atmospheres in the trunk AK-74), which pushes the bullet forward. The longer the gases act on the bullet, the greater the speed it will gain. That's why barrel length critically important: in a short barrel, gases have time to escape earlier, without transferring maximum energy to the bullet.
Key stages of bullet acceleration:
- 🔥 Primer ignition - starts a chain reaction of gunpowder combustion.
- 💨 Increase in gas pressure — at its peak reaches values exceeding the pressure in the truck tires by 100+ times.
- 🚀 Movement of a bullet along the rifling of a barrel - rotation stabilizes flight, but slightly reduces speed due to friction.
- 🎯 Departure from the barrel - the moment when the bullet speed is maximum (then it begins to fall due to air resistance).
Interesting fact: first 0.001–0.002 seconds after the shot the bullet travels only 10–20 cm trunk, but is already gaining 50% final speed. The remaining meters of the barrel are needed to “pump up” the speed to the maximum.
Bullet speed in different modifications of AK
Kalashnikov assault rifles were produced with different cartridges, and this directly affects the speed characteristics. Let's look at the most common models:
| Model AK | Cartridge | Bullet speed (m/s) | Barrel length (mm) | Bullet energy (J) |
|---|---|---|---|---|
| AK-47 (1947) | 7.62×39 mm | 710–730 | 415 | 1990–2070 |
| AKM (1959) | 7.62×39 mm | 715–735 | 415 | 2050–2100 |
| AK-74 (1974) | 5.45×39 mm | 880–900 | 415 | 1320–1470 |
| AK-12 (2018) | 5.45×39 mm / 7.62×39 mm | 880–900 / 715–735 | 415 | 1470 / 2100 |
| AKS-74U (shortened) | 5.45×39 mm | 735–750 | 210 | 950–1000 |
Critical observation: shortened versions (e.g. AKS-74U) lose up to 15–20% of bullet speed due to the shortened barrel. This directly affects the firing range and accuracy. For example, at a distance 300 m bullet from AK-74 saves energy in 1.5 times higherthan from AKS-74U.
It is also worth noting that the cartridge 5.45×39 mm (used in AK-74) was originally developed for higher initial speed, but lower bullet weight. This gives a flatter trajectory, but reduces penetrating power at long distances.
The 5.45x39mm cartridge provides greater velocity but less energy compared to 7.62x39mm. The choice depends on the task: accurate shooting at medium distances vs. penetrating force on loved ones.
Factors affecting bullet speed
Even in the same machine gun, bullet speed can vary. Here are the key factors:
- 🌡️ Air and cartridge temperature: Cold powder burns more slowly, reducing speed by
10–30 m/s. When-20°Cthe difference can reach50 m/s. - 📏 Barrel length: every centimeter of the trunk adds
2–5 m/sto speed. Shortened versions (for example, AK-105 with barrel314 mm) are inferior in speed to standard models. - 💦 Powder moisture: old or improperly stored cartridges can give speed at
5–10%lower than stated. - 🏔️ Altitude: on top
2000 mbullet speed increases by1–2%due to less air resistance. - 🎯 Barrel wear: after
10,000–15,000 shotsspeed may drop by3–5%due to erosion of the rifling.
Practical example: in mountainous conditions (for example, in Afghanistan), soldiers noted that bullets from AK-74 flew “further and more accurately” than on the plain. This is due to the thin air, which slows down the bullet less.
The myth about “supersonic” AK bullets
Many people think that an AK bullet travels faster than the speed of sound (343 m/s). This is only true for 5.45x39mm and 7.62x39mm cartridges - their speed exceeds 700 m/s. However, at distances over 300–400 m, the bullet slows down to subsonic speeds, which affects its stability in flight.
How to measure bullet speed: methods and instruments
Accurately measuring bullet velocity requires specialized equipment. There are several methods in the arsenal of ballisticians:
- Chronograph - an optical or radar device that records the time of flight of a bullet between two sensors. Accuracy:
±0.5%. - Doppler radar — measures the change in frequency of the reflected signal from a flying bullet. Used in military ballistics.
- High speed video shooting - cameras with frequency
10,000+ fpsallow you to calculate the speed from the displacement of the bullet between frames. - Ballistic pendulum (obsolete method) - measures the energy of the bullet by the deflection of the pendulum, but does not give an accurate speed.
For amateur measurements most often used optical chronographs (for example, MagnetoSpeed or Caldwell Ballistic Precision\)). They are compact and allow you to measure speed right at the shooting range. Average price of such a device: 20,000–50,000 rubles.
⚠️ Attention: Measuring bullet velocity without certified equipment and permission may be considered a violation of firearms regulations. In Russia, such measurements require a ballistic testing license.
If you're shooting on the range and want to get a rough estimate of bullet speed, pay attention to the sound. 5.45 mm caliber bullet from AK-74 at a distance of 100 m it beats the sound of a shot by about 0.2–0.3 seconds (depending on the air temperature).
Comparison of AK bullet speed with other types of weapons
To understand how fast a bullet from a Kalashnikov assault rifle is, let’s compare it with other popular types of small arms:
| Weapons | Cartridge | Bullet speed (m/s) | Differences from AK |
|---|---|---|---|
| SVD sniper rifle | 7.62×54 mm R | 830–850 | A long barrel and a powerful cartridge give +100 m/s speed compared to AKM. |
| Makarov pistol (PM) | 9×18 mm | 315–335 | Speed in 2.2 times lowerthan AK-47. |
| M16A4 assault rifle (USA) | 5.56×45mm NATO | 950–970 | The NATO cartridge gives +50–70 m/s compared to 5.45x39 mm. |
| Shotgun "Saiga-12" | 12 gauge (shot) | 380–420 | Fraction speed is lower in 2 times, but the energy at close range is comparable. |
From the table it is clear that AK-74 inferior in speed M16 due to a less powerful cartridge, but superior to most pistols and shotguns. I wonder what sniper rifles even with the same caliber (7.62 mm) they show better results due to the long barrel and optimized cartridges.
Practical application: how bullet speed affects shooting
Knowing the bullet's speed helps the shooter adjust his sights and choose the optimal distance. Here's how it works in practice:
- 🎯 Flight path: bullet with speed
900 m/s(5.45x39 mm) flies straighter than a bullet715 m/s(7.62x39 mm). This simplifies aiming at distances up to300 m. - 💥 Penetrating power: Despite the lower speed, the 7.62 mm bullet retains energy better at longer distances. For example, on
500 mshe breaks through a steel sheet2–3 mm, while 5.45 mm is only1–1.5 mm. - 🌬️ Wind drift: the higher the speed, the less the bullet deviates from the course in crosswinds. Bullet from AK-74 at a distance
400 mblown away by the wind5 m/son20–25 cm, and the bullet from AKM - on30–35 cm. - 🔊 Sonic boom: bullets with speed >
343 m/screate a shock wave that is heard as a "click". This can unmask the shooter.
An example from hunting practice: when shooting at a moving target (for example, a wild boar), the high speed of a 5.45 mm bullet allows you to “anticipate” the movement less, since the bullet reaches the target faster. However, for large animals (elk, bear), experienced hunters prefer 7.62 mm due to its greater stopping power.
Select a cartridge with the optimal velocity for the task|Consider the air temperature (cold reduces the speed)|Adjust the sight taking into account the wind|Check barrel wear (erosion reduces accuracy)|Use a ballistic calculator for calculations-->
Security and legal aspects
The possession and use of a Kalashnikov assault rifle in Russia is strictly regulated by law. Here are the key points you need to know:
- 📜 Weapon license: A permit is required to store and carry an AK
Russian National Guard. For civilians, automatic versions (for example, AK-74) are not issued - only self-loading carbines (for example, Saiga). - 🎯 Shooting locations: Shooting is permitted only at certified shooting ranges or firing ranges. Independent shooting in the forest or in the country is punishable under Art.
222 of the Criminal Code of the Russian Federation(illegal handling of weapons). - 🔧 Modifications: any changes in the design of the weapon (shortening the barrel, installing a silencer) require re-registration. Unauthorized modifications are equivalent to the manufacture of weapons.
- 📊 Ballistic examination: When a crime is committed using a weapon, bullets and shell casings are analyzed. Even if you didn't shoot, the presence of ammunition from your gun at a crime scene can become evidence.
⚠️ Attention: Storing ammunition separately from weapons does not relieve responsibility. By law, ammunition must be stored in a safe with the weapon or in a separate locked box. Violation of storage rules entails a fine of up to 50,000 rubles or deprivation of a license.
If you are planning to purchase an AK-based self-loading carbine (for example, Saiga-7.62 or Boar), please note that the registration process will take 2–3 months and will require:
- Passing a medical commission (narcologist + psychiatrist).
- Providing documents confirming the presence of a safe.
- Payment of state duty (
2,000 rublesfor license +500 rublesfor storage permission).
FAQ: Frequently asked questions about AK bullet speed
Why does a bullet from an AK-74 travel faster than an AK-47, but does less damage?
The 5.45x39 mm bullet is lighter (3.4 g versus 7.9 g for 7.62x39 mm) and has a more streamlined shape, which reduces air resistance. Due to this, it accelerates to 900 m/s, but loses energy faster over longer distances. The 7.62 mm bullet is heavier and retains kinetic energy longer, so it is more effective at distances beyond 300 m.
Is it possible to increase the speed of an AK bullet by shortening the barrel?
No, this is a common misconception. Shortening the trunk reduces bullet speed, since the gases do not have time to completely transfer energy. For example, trunk AKS-74U (210 mm) gives speed 735 m/s against 900 m/s at the standard AK-74 (415 mm). To increase speed, other measures are needed: more powerful powder, an optimized bullet or a long barrel.
How does temperature affect bullet speed?
As the temperature drops, the powder burns more slowly, which reduces the pressure in the barrel. For example, when -20°C bullet speed from AKM may fall from 730 m/s up to 680–700 m/s. In hot climates (+30°C and above), the speed, on the contrary, increases by 10–20 m/s, but the risk of increased barrel wear increases.
What is the danger of shooting from an AK with a worn barrel?
Erosion of barrel rifling (after 10,000–15,000 shots) leads to:
- Reducing bullet speed by
3–5%. - Deterioration in accuracy (bullets fly less predictably).
- Increased risk of barrel rupture when shooting.
It is recommended to have the barrel checked by a gunsmith every 5,000 shots.
Is it possible to legally measure the speed of a bullet from your weapon in Russia?
Yes, but only at a licensed shooting range with the permission of the administration. For this purpose, certified chronographs are used (for example, MagnetoSpeed). Independent measurements outside the test site are prohibited and can be regarded as ballistic tests without a license (Art. 223 of the Criminal Code of the Russian Federation).