AK-74: Encyclopedia II - AK-74 - Ballistics

AK-74 - Ballistics

The weapon fires a 5.45 × 39 mm round with a muzzle velocity of 900 m/s. Muzzle energy is 1.39 kilojoules, giving an effective range of around 500 m. Cartridge weight is 10.75 g. Projectile weight is 3.42 g. The new cartridge was designed to give greater effective range, less recoil, and a flatter trajectory than the 7.62 x 39 mm.

The 5.45 mm bullet yaws when striking a soft target such as a human causing it to tumble. This tumbling creates a larger wound in the target than the bullet's diameter. The Afghans who fought the Soviet Union often referred to the 5.45 mm as "the poison bullet" because of the severity of the wound in proportion to its relative anemic size and energy. Reports from Afghanistan suggested that the new bullet might violate international conventions on rifle ammunition. It was suggested that its radical design would create inhumane wounds.

Design of an entirely new cartridge was possibly a reaction to the effectiveness of the 5.56 × 45 mm round in Vietnam. All military rifle bullets will turn or yaw in soft tissue. Small-caliber high-velocity projectiles like the 5.56 mm produce significant wounds because they yaw much sooner in soft tissue, greatly increasing their frontal area.¹ The Soviets designed a round that would be similar to the 5.56 mm, but with an increased tendency to yaw. The 5.45 mm projectile consists of a mild steel core in the rear with a lead plug in front. The copper-plated steel jacket of the bullet incorporates an air space in the nose. This empty space has several functions. It moves the center of gravity rearward, encouraging yaw in soft targets. It also streamlines and lightens the projectile resulting in greater velocity, flatter trajectory, and more reliable feeding from the magazine. Finally, this space often collapses and deforms irregularly in soft targets. Despite its complicated design, the bullet fired by the AK-74 fails to reliably fragment in soft tissue making it less effective in this area than similar Western designs. It has also been shown to yaw no sooner than the 5.56mm projectiles.

The development of the AK-74 bullet is often compared to that of the American M16 rifle and its M193 ammunition. This ignores the fact that NATO was in the process of developing the SS109 ammunition at the time and the two were likely developed in parallel with similar criteria. When the SS109 5.56 mm bullet is compared side-by-side with the 5.45 x 39mm they are similar in many ways. They are both composed of a separate jacket, steel core, and lead component. As with the SS109, the 5.45 mm was likely designed as a compromise between penetration and soft-tissue damage. The major threat at the time of development was the American soldier who was increasingly utilizing body armor. Not surprisingly, the 5.45 mm bullet is more effective against Kevlar than the earlier 7.62 mm bullet. The 5.45 mm and 5.56 mm cartridges are considered equal in most aspects with the exception of the Western round having a significantly greater tendency to fragment when fired at close range.

Adapted from the Wikipedia article "Ballistics", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki