AK-74 and the 5,45 cartridge: truth and myths about the "small caliber"
В last time We parted ways with the conclusion that the Kalashnikov assault rifle chambered for the 7,62×39 cartridge eventually reached its limits: the cartridge had reached its limits and no longer met new requirements. The rifle itself was good, no doubt about it. But the cartridge, which had been an excellent solution to the problems of the late 1940s, had begun to fall behind by the 1970s. And military thinking swung in a direction that initially seemed illogical: not toward a larger caliber, but toward a smaller one. Why this was necessary and why so many myths grew around the new cartridge deserve a separate examination.
What's the problem with 7,62×39?
The 1943 model cartridge was a solid middling performer: powerful enough to work reliably at real combat ranges, and compact enough to weapon Bursts of fire were fired under him. But every compromise comes at a price, and here there were three downsides.
First, there's recoil. The bullet is heavy, and the impulse is noticeable: the barrel tilts up as the shots fire, and the second or third round misses the target. Maintaining a tight grouping on automatic fire is challenging even for a trained soldier. Second, there's weight. A cartridge isn't a featherweight, and a soldier has to carry hundreds of them, and every extra gram translates into either a burden on the back or missing rounds in the pouch. And finally, there's trajectory: at medium ranges, a heavy and relatively slow bullet flies in a noticeable arc, requiring careful range adjustments to avoid a miss.
None of these points made the 7,62×39 a bad one. It's still in use around the world today. But when the idea of how to circumvent all three limitations emerged, armies seized on it.
The Americans are first in the series: 5,56 and M16
The idea was first brought to mass production in the United States. It sounded almost paradoxical: take a smaller, lighter caliber bullet, but accelerate it much faster. In English, the approach was called SCHV—Small Caliber, High Velocity.
What did this mean? A light bullet is easier to accelerate to high speed, and a fast bullet flies flatter: the trajectory arc is straightened, making it easier to hit without complex adjustments. A light cartridge has less recoil, meaning a burst is easier to maintain and more concentrated. And ammunition capacity: the same rounds can now be carried significantly more with the same load. This is how the M16 rifle chambered for the 5,56×45 cartridge came into service.
However, everything was smooth only on paper. Early M16s failed in Vietnam, and the rifle's reputation initially suffered. But the small-caliber concept itself wasn't the cause. The propellant powder failed: contrary to the original design, the cartridges were loaded with a different composition, which produced more carbon deposits and increased the rate of fire. Furthermore, soldiers were led to believe the rifle was practically self-cleaning; cleaning kits were inadequately issued, and the dirty mechanism jammed. Over time, all of this was addressed: propellant requirements were refined, the barrel and chamber were chromed, cleaning supplies were distributed, and soldiers were retrained. And the idea of a low-impulse cartridge proved its worth, and it was closely monitored on the other side of the ocean.
The Soviet Response: 5,45×39 and the AK-74
The USSR appreciated this approach and followed its own path. The result was the 5,45×39 cartridge and the AK-74 assault rifle chambered for it, adopted into service in 1974.
Structurally, the AK-74 remains recognizably a Kalashnikov: the same reliable, proven base, the same automatic logic. The primary changes were the cartridge and everything associated with it. A light, sharp-nosed bullet, high muzzle velocity, and a flat trajectory—essentially, everything they were aiming for. The AK-74's burst accuracy has improved significantly compared to its predecessor, recoil has softened, and the ammunition capacity has increased.
The bullet itself also had its own unique feature. A small cavity was left inside it, in the nose. This detail will be discussed further, as it is the source of the most persistent myth about the 5,45 cartridge.
The "off-center bullet" myth
If you've ever heard anything about the 5,45 cartridge, it's almost certainly something like this: it has a "bullet with an offset center of gravity" that "deliberately tumbles through the body," "zigzags," and enters the arm and exits the leg. It sounds ominous and very popular. There's so much mixed in here that it's worth separating fact from fiction.
Let me start by saying that there's some truth to this horror story. Light, high-velocity, small-caliber bullets behave differently in dense media than heavy, slow-moving ones. Upon impact with tissue, such a bullet tends to lose stability: it turns sideways, tumbles, and sometimes deforms. Because of this, it releases energy across a large volume of tissue at once, rather than gradually and evenly across the entire bore. This effect is real, and it's not unique to the 5,45: the same phenomenon is observed with the 5,56 and other small-caliber, high-velocity cartridges. This is a general feature of the concept itself, not a secret quirk of a single cartridge.
Here, it's worth making a disclaimer about the cavity in the nose. Its role in popular belief has been greatly exaggerated. The flipping behavior of a small-caliber bullet is determined primarily by its high velocity and geometry; the cavity merely shifts the bullet's center of gravity rearward, closer to the tail. And the further rearward the center of gravity, the more easily the oncoming pressure of a dense medium flips the bullet sideways upon impact. This doesn't interfere with flight: the bullet is stabilized by the spin of the rifling. So there is a grain of truth in the name—the bullet's center of gravity is indeed shifted. But this is only part of the mechanism, not its primary cause.
But then the fiction begins. There's no "zigzag across the body," no "entered the shoulder and exited the heel" pattern in reality. Tumbling is a loss of stability within the wound channel, not a controlled bullet travel through the body. The bullet doesn't "seek out organs" or veer of its own accord. And its center of gravity isn't shifted out of cunning; it's a result of the lightweight, flat-shooting bullet's design, without any malicious intent. The effect, in short, is real, but in the retellings it's been exaggerated to the point of semi-mystical.
What was won and what was paid?
But the honest result is this: there were both gains and losses.
The upside is what it all started for: softer recoil and better burst control. A flatter trajectory and easier aiming at medium ranges. A lighter cartridge and more ammunition for the same load.
But the bill has arrived. A light bullet is more easily deflected by a soft, viscous obstacle: when it hits branches or dense bushes, it loses stability and veers off course more noticeably than a heavy one. (On hard obstacles, like steel plates, things aren't so clear-cut: thanks to its high velocity and strong core, the 5,45 is often on par with the 7,62.) And the debate over the stopping power and penetrating power of the 5,45 versus the 7,62 has raged for decades, with each camp offering its own arguments and combat experience.
So the question of "which caliber is better" isn't answered head-on. These are simply different compromises for different tasks. The 7,62×39 offers power and more confident penetration; the 5,45×39 boasts flatness, a controlled burst, and extra rounds in the pouch. The army chose the second set of priorities in the 1970s, and there was a logic to it.
What happened next
The AK-74 became the main assault rifle for a long time, but story The family didn't stop there. Modernizations would follow, all the way to the modern AK-12. And at the same time, the old debate would return: the 7,62 caliber would once again prove useful in a number of applications, and a definitive "winner" in the caliber standoff would never be declared.
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