Magazines equipped with 5,56x45 mm cartridges
Even if you are not into firearms weapons, then most likely you can still list a few common calibers. And if we narrow the range to long-barreled weapons, then for sure - two. The most widespread in the world are two cartridges for automatic weapons: 5,56x45 mm and 7,62x39 mm. The former is the standard NATO assault rifle cartridge, while the latter is inextricably linked to the famous AK-47 and its many clones and is even more widespread.
The armies of many countries around the world, as well as the police forces, rely on these two cartridges for their excellent performance, time-tested. The ammunition has won its place in the sun thanks to its good firing range, accuracy, and lethality. Moreover, each of these two cartridges has its own characteristics. In some ways one is better, in other ways the other. The debate about which particular patron is more successful continues today, especially often heated discussions can be observed on the Internet. At the same time, one should not forget that it is very difficult to find the truth in such a dispute. In a real battle, much depends not so much on the cartridge itself, but on the shooter, his level of training and possession of the weapon, as well as the weapon itself.
At the same time, the armies do not abandon both calibers, since the systems adopted for service are focused on solving different combat missions. If machine guns / assault rifles today are almost always produced in caliber 5,56 (NATO) or 5,45 (Soviet / Russian systems), then sniper weapons and machine guns are still presented in caliber 7,62x51 (NATO) or 7,62x54 ( Russia). But now we will talk first of all about intermediate cartridges and their advantages and disadvantages.
When did the most common intermediate cartridges appear?
The most common intermediate cartridges in the world are 5,56x45 mm and 7,62x39 mm. The old man here is the Soviet intermediate cartridge 7,62x39 mm, model 1943. This ammunition was developed during the Second World War, but was not used in combat conditions. The creation in the USSR of a 7,62-mm intermediate cartridge and its adoption into service opened up new perspectives in the design of various types of automatic weapons. The famous Kalashnikov assault rifle, AK-1949, which was adopted in 47, was created specifically for this cartridge. Together with the AK, the 7,62x39 cartridge spread widely throughout the world in the postwar years. So much so that in the 1960s, the possibility of adopting it as an additional machine gun cartridge in NATO countries was even seriously discussed.
Soviet cartridges: 7,62x54 mm (rifle), 7,62x39 mm (intermediate) and 7,62x25 mm (pistol)
However, it never came to that. Largely due to the appearance of an intermediate low-pulse cartridge 5,56x45 mm. This cartridge was developed in the USA in 1959 and went into production in 1961. The cartridge was created on the basis of the existing .223 Remington hunting ammunition. As with the Kalashnikov assault rifle, the proliferation of ammunition was facilitated by the creation of effective small arms. It was under this cartridge that Eugene Stoner developed almost all of his small arms models, including the famous M16 assault rifle. In the 1970s, the cartridge began to be widely distributed in NATO countries and by the mid-1980s it became the standard for all NATO countries.
The development of intermediate cartridges in the USSR and the USA was preceded by the same conclusions. Existing rifle cartridges were overly powerful for modern automatic weapons. At the same time, the standard NATO cartridge 7,62x51 mm was recognized as too heavy, which directly influenced the ammunition carried by the soldier. In the changed conditions of warfare, this was no longer acceptable. In addition, intermediate cartridges ensured a reduction in the mass of the weapon itself, reduced recoil when firing, which ensured a large effective range of fire in bursts.
Obviously, the 7,62mm cartridge weighed more than the 5,56mm. At first glance, the difference is not that big: 16 grams versus 12 grams. However, in an ammunition load of 100 rounds, this already gave 400 grams of difference. And if we consider the standard gunner's ammunition from 8 magazines, the difference becomes even more noticeable, since the weight of the ammunition we carry grew by a kilogram. For long marches, this is already very important. That is why, by 1974, an intermediate low-impulse cartridge of 5,45x39 mm caliber was also created in the USSR, which is distinguished by an even lower weight - 10 grams.
What are the pros and cons of cartridges 7,62x39 and 5,56x45
Both intermediate cartridges are widely used in armies around the world to this day. That said, it is very difficult to determine which one is better for the average shooter (largely due to the bias of such assessments: in some cases it will be exclusively about the shooter's preferences). To avoid this, usually try to evaluate ammunition in three main categories: power, recoil and accuracy. It is easier to compare with these categories, since all three parameters can be easily assessed both theoretically and in practice.
Cartridges: 7,62x39 mm (left) and 5,56x45 mm (right)
The 5,56x45 mm small-impulse intermediate cartridge created later has a number of undeniable advantages. Its bullet is almost two times lighter than the bullet of the cartridge 7,62x39 mm. Therefore, even despite the increased flight speed, the recoil momentum was reduced. This had a positive effect on the accuracy of firing from automatic weapons. The machine gun shook less corny when firing in bursts. For the shooter, it became more comfortable to fire, the dispersion decreased, and, therefore, the probability of hitting the target also increased.
Among other things, due to the higher speed of the bullet, the flatness of the trajectory improved. For a shooter who uses 5,56 mm rounds, it is easier to aim, since there are fewer adjustments for wind or altitude. This is especially important for long-range shooting. The average speed of the bullet of the cartridge 7,62x39 mm is 720 m / s, for the bullet of the cartridge 5,56x45 mm it is already 1006 m / s. At a distance of 100 meters, there is still no difference in reducing the trajectory of a bullet for two cartridges, but already at a distance of 250 meters, the 7,62-mm bullet decreases by 40 cm. The flight trajectory of a bullet of a 5,56 mm cartridge is flatter and provides a longer effective direct shot. At a distance of up to 250 meters, it practically does not decrease.
Despite all of the above, the most common machine gun cartridge on the planet is still the Soviet 7,62x39 mm, which was sold around the world thanks to the AK-47 machine gun and its numerous copies, both licensed and not so much. This ammunition also has its advantages. The first and most obvious is the weight of the bullet. Ammunition of this caliber is more preferable if you are firing at a target in body armor. A heavy bullet retains energy much better at long distances, having a better striking and stopping effect.
The advantages of 7,62x39 mm cartridges are also a lower probability of a ricochet and a much more stable overcoming of obstacles. The bullet confidently overcomes thickets, leaves, branches, while a 5,56-mm bullet can seriously change the trajectory, meeting even a minor obstacle. What can we say, boards and bricks for 7,62 mm ammunition are often also quite surmountable obstacles. At the same time, if it hits the bone, such a bullet provides a more severe wound. On the other hand, low-impulse intermediate-caliber cartridges provide more severe wounds, falling into soft tissues.
The most common weapon on the planet: AK-47 with cartridges 7,62x39 mm
The obvious disadvantages of the 7,62x39 mm cartridge include higher recoil when firing. The high recoil makes it difficult for the shooter to be able to accurately second and third shots, depending on the weapon he is using, as well as the very ability to fire efficiently and accurately in bursts. In turn, due to the flatter trajectory, low-impulse intermediate cartridges are considered easier for massive armies with a conscription system, when a large number of new soldiers must be constantly trained in shooting. This is not the last reason why the 5,45 mm cartridge is still the most popular in Russia, although the military is discussing options for returning to the 7,62 mm caliber or creating new ammunition.
If we sum up the results when comparing according to three main criteria, then everything is quite simple. The intermediate cartridge 7,62x39 mm wins in power, but loses to the cartridge 5,56x45 mm in accuracy and recoil. For the average shooter, when firing at long distances, the intermediate low-impulse cartridge 5,56x45 mm, as well as its Russian counterpart 5,45x39 mm, seem to be more preferable.