Initial velocity of a Kalashnikov bullet: technical data and influencing factors

Initial bullet speed of a Kalashnikov assault rifle AK-74 (5.45×39 mm) is 900–910 m/s when firing from a standard length barrel of 415 mm, whereas AKM (7.62×39 mm) this figure is lower - 715–725 m/s. The difference is due not only to the caliber, but also to the design of the cartridge: the 5.45 mm bullet has a lower mass (3.4 g versus 7.9 g for the 7.62 mm) and a more effective powder charge. These parameters are critical for ballistic calculations, long-range shooting accuracy and penetration assessment.

It is important to consider that the actual speed may deviate from the rated values by ±10–15 m/s due to barrel wear, ambient temperature or ammunition quality. For example, when shooting in cold weather (-20°C), the bullet speed AK-74 decreases by 30–50 m/s, and in the heat (+30°C) - increases by 10–20 m/s. Such fluctuations affect the trajectory and accuracy, which is especially noticeable when firing at distances over 300 meters.

In modern modifications, such as AK-12 or AK-15, the initial bullet velocity remains at the level of classical models, but due to improved ergonomics and barrel stabilization, the spread of values is reduced. For comparison: the American M16A4 (5.56x45mm NATO) muzzle velocity reaches 948 m/swhat's on 4–5% higher than that AK-74, but this advantage is offset by the greater mass of the weapon and sensitivity to contamination.

Initial speed specifications by model

The speed of the bullet as it exits the barrel depends on a combination of three key factors: barrel length, bullet mass and powder charge energy. Below are the passport data for the main modifications of Kalashnikov assault rifles, confirmed by GOST and factory tests:

Machine model	Caliber, mm	Barrel length, mm	Bullet weight, g	Initial speed, m/s	Muzzle energy, J
AK-47 (first episodes)	7,62	415	7,9	710–720	1990–2040
AKM	7,62	415	7,9	715–725	2010–2070
AK-74	5,45	415	3,4	900–910	1420–1460
AK-74M	5,45	415	3,4	890–900	1390–1420
AK-12 (5,45×39)	5,45	415	3,4	905–915	1440–1480

Please note: for shortened versions (for example, AKS-74U with a 200 mm barrel) the bullet speed drops to 735–750 m/s due to reduced acceleration time. This leads to a reduction in muzzle energy by 30–35%, which is critical for breaking through body armor or overcoming obstacles.

⚠️ Attention: The use of non-standard cartridges (for example, with an enhanced charge) can increase the muzzle velocity by 50–80 m/s, but at the same time, barrel wear and the risk of cartridge case rupture sharply increases. Such experiments are prohibited by military regulations.

Factors affecting bullet speed

Even under ideal conditions, muzzle velocity can vary. Main reasons for deviations:

• 🔥 Powder temperature: When heated to +50°C, the speed increases by 15–25 m/s, when cooled to -30°C - decreases by 40–60 m/s. This is due to a change in the burning rate of the powder charge.
• 📏 Barrel length: Every 10 cm trunk shortening reduce speed by 20–30 m/s. For example, at AK-105 (barrel 370 mm) bullet speed 5.45 mm at 5% lower than AK-74.
• 💨 Barrel contamination: Carbon deposits and copper deposits increase friction, reducing speed by 5–10 m/s after 500–600 shots without cleaning.
• 🎯 Ammo quality: Military-grade cartridges (for example, 7N6 for AK-74) provide stability of ±5 m/s, while commercial analogues can provide a spread of up to ±20 m/s.

To minimize the influence of external factors in military conditions, use:

• 🔄 Barrel preheating: A series of 3-5 shots before the fight stabilizes the temperature of the metal.
• ❄️ Storing ammunition in thermal cases: Prevents overheating or hypothermia of cartridges.
• 🧹 Regular barrel cleaning: After every 300 shots, a mandatory procedure using a copper solvent (for example, CHMS-4).

Comparison with foreign analogues

The muzzle velocity of a Kalashnikov bullet is often compared to NATO standards. Despite the lower speed compared to M16 or HK416, AK series assault rifles demonstrate better reliability in extreme conditions. Below is a comparison table:

Model	Caliber	Initial speed, m/s	Muzzle energy, J	Features
AK-74	5.45×39 mm	900–910	1420–1460	High accuracy at distances up to 500 m
M16A4	5.56x45mm NATO	948–970	1700–1800	Sensitive to dirt, high impact
HK416	5.56x45mm NATO	920–930	1650–1720	Piston system, less wear
Steyr AUG	5.56x45mm NATO	920–940	1680–1750	Bullpup layout, high precision

Key Advantage AK-74 — speed stability in the temperature range from -50°C to +50°C. For example, at M16 at -30°C the bullet speed drops by 80–100 m/s, which requires reconfiguring the sight. At the same time, the muzzle energy of NATO cartridges is 15–20% higher, which gives an advantage in breaking through light cover.

Why does the AK-74 have a lower bullet speed than the M16, but better accuracy?

The reason lies in the design of the bullet and barrel. The 5.45x39mm bullet has a longer and heavier core (steel, with an air cavity in the nose), which provides better aerodynamics at long ranges. In addition, the barrel rifling pitch AK-74 (1:7.87) is optimized to stabilize a light bullet, while M16 (1:7 or 1:9) it is designed for heavier NATO cartridges. This leads to the fact that when shooting from M16 With light bullets (for example, M193), excessive stabilization occurs, which worsens accuracy at distances over 300 m.

How to measure initial speed yourself

To accurately measure bullet speed in the field, use ballistic chronometers (for example, MagnetoSpeed V3 or Chrony F-1). These devices record the time of passage of a bullet between two sensors, the distance between which is known (usually 1 m). Calculation algorithm:

1. Install sensors at a distance 1 meter from each other, on the firing line.
2. Fire the shot. The chronometer will record the time t (in seconds) the bullet passes between the sensors.
3. Calculate the speed using the formula: V = 1 / t (where V — speed in m/s).

The error of such measurements is ±1–3 m/s. To improve accuracy:

• 📊 Spend a series of 5–10 shots and average the results.
• 🌡️ Measure the temperature of the air and gunpowder - this will allow you to correct the data.
• 🎯 Use a tripod to fix the chronometer to eliminate vibrations.

⚠️ Attention: When measuring bullet speed prohibited be closer than 5 meters from the line of fire. Even a ricochet from the sensor can cause injury. Carry out all manipulations with the chronometer up to started shooting.

Effect of bullet speed on ballistics and accuracy

The initial speed directly determines bullet flight path, her resistance to side winds and penetration ability. For example, at speed 900 m/s (like AK-74) the 5.45 mm bullet maintains supersonic speed up to a distance 600–700 m, whereas with 715 m/s (AKM) the transition to subsonic occurs already at 300–350 m. This affects:

• 🎯 Firing accuracy: At a distance of 500 m, bullet spread AK-74 amounts to 15–20 cm, and AKM — 25–30 cm under the same conditions.
• 💥 Penetrating ability: At a speed above 850 m/s, a 5.45 mm bullet penetrates a 5 mm steel sheet, while a 7.62 mm bullet requires a speed of at least 700 m/s.
• 🌬️ Wind drift: A bullet with a lower speed is deflected more by the side wind. For example, with a wind of 5 m/s, the drift of a bullet AKM reaches 300 m 25 cm, and AK-74 — 18–20 cm.

To compensate for the effect of speed on accuracy, use:

• 🔧 Sight adjustment: On AK-74 when shooting at 500 m, the sight is set to division “5”, but when the bullet speed is below 880 m/s, the correction requires a shift by +0.5 divisions.
• 📉 Ballistic calculators: Programs like Strelok Pro take into account bullet speed, temperature and humidity to calculate corrections.

Myths and misconceptions about the speed of the Kalashnikov bullet

There are many myths surrounding the muzzle velocity of AK bullets, often due to lack of awareness or outdated data. Let's look at the most common ones:

1. "The AK-74 shoots faster than the AKM due to its smaller caliber."
   

   In fact, speed does not depend on caliber, but on ratio of bullet mass and powder charge energy. The 5.45 mm bullet has a mass 2.3 times less than the 7.62 mm bullet, and the charge energy is optimized for a light bullet.

2. "Shorter barrels do not affect speed."
   

   In practice, AKS-74U (200 mm barrel) bullet speed drops to 735 m/swhat's on 18% lower than full size AK-74. This leads to a reduction in the effective fire range from 500 to 300 m.

3. "The speed of a bullet does not change over time."
   

   Barrel wear (rifling erosion) reduces speed by 1–2 m/s after every 5000 shots. With critical wear (rifling depth less than 0.1 mm), the speed may drop by 50–70 m/s.

Another common misconception is "the higher the speed, the better". In fact, excessive speed leads to:

• 🔥 Increased barrel wear (lifetime is reduced by 20–30%).
• 🎯 Deterioration of accuracy due to barrel vibrations during firing.
• 💥 Increased recoil, which reduces control over the weapon in automatic mode.

Practical implications of changing bullet speed

The deviation of the bullet speed from the nominal values affects the combat characteristics of the weapon. Let's look at specific scenarios:

Speed change	Reason	Consequences for shooting	Recommendations
+50 m/s (for example, 950 m/s instead of 900 m/s)	Increased powder charge, barrel overheating	Increased range by 50–70 m, but increased barrel wear and risk of case rupture	Use only certified ammunition, avoid overheating
-50 m/s (for example, 660 m/s instead of 710 m/s)	Cold weather, barrel wear	Reduced range by 100–150 m, increased dispersion by 30–40%	Adjust the sight, clean the barrel after 300 shots
Instability ±20 m/s	Low quality cartridges, barrel contamination	Inability to shoot accurately at distances over 200 m	Use cartridges from the same manufacturer, clean your weapon regularly

For sniper modifications (for example, SVD or SV-98) Bullet speed control is critical. So, when shooting at 600 m, the speed deviation is 10 m/s leads to a shift of the point of impact by 15–20 cm. In combat conditions, this could mean missing a target the size of a human figure.

⚠️ Attention: When firing tracer cartridges (for example, 7T3 for AKM) the initial speed decreases by 3–5% due to the greater mass of the bullet. This must be taken into account when zeroing a weapon.

FAQ: Frequently asked questions about the speed of the Kalashnikov bullet

Why does the AK-74 have a higher bullet speed than the AKM if the caliber is smaller?

This is due to cartridge design. The 5.45x39 mm bullet has a lower mass (3.4 g versus 7.9 g for the 7.62 mm), but the powder charge is optimized for acceleration of a light bullet. In addition, the bullet's shape (with a pointed nose and an air cavity) reduces drag, allowing it to maintain speed over long distances.

How does temperature affect bullet speed?

As the temperature drops, the powder burns more slowly, which reduces the pressure in the barrel and, accordingly, the speed of the bullet. For example, at -30°C the bullet speed AK-74 falls to 850–860 m/s. In hot weather (+30°C) the speed can increase to 920–930 m/s, but this accelerates barrel wear. Optimal temperature range for stable shooting: from -10°C to +25°C.

Is it possible to increase the speed of an AKM bullet without changing the cartridges?

Theoretically, yes, but in practice it is impractical. For example, shortening the bolt carrier spring or polishing the barrel can give an increase in 5–10 m/s, but this will increase recoil and wear of parts. A more effective way is to use cartridges with enhanced charge (for example, 7N23), but they are intended for sniper rifles and are not recommended for machine guns due to increased pressure.

What is the bullet speed of the AK-12 and AK-15?

U AK-12 (5.45×39 mm) initial speed is 905–915 m/swhat's on 5 m/s higher than that AK-74, thanks to improved barrel geometry. U AK-15 (7.62×39 mm) speed is maintained at AKM — 715–725 m/s, but due to the new design of the bolt group, the spread of values is smaller.

How does bullet speed affect penetration?

Penetration ability depends on kinetic energy (E = m*V²/2). For example, a bullet AK-74 (3.4 g, 900 m/s) has energy 1420 J, and the bullet AKM (7.9 g, 715 m/s) - 2010 J. However, in practice, a 5.45 mm bullet is better at penetrating light obstacles (for example, plywood or thin metal) due to its smaller diameter and higher speed. For body armor, not only speed is critical, but also the shape of the core.