Top view of a lot of 5.45x39mm 7N6 cartridges.
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The 5.45x39mm is a late Cold War era rifle cartridge of Soviet origin. In the early 1960's the USSR came into possession of the 5.56x45mm M193 round used in the US M16A1 rifle during the Vietnam war. The limited weight, flat trajectory and limited recoil of the 5.56x45mm round resulted in the USSR developing a similar round. It was found that the AKM would be a good platform for such a new rifle cartridge. This development resulted in the AK-74 assault rifle that became the standard issue rifle in the USSR and was widely exported.
The 5.45x39mm round uses a bottlenecked case that is based on the one used for the 7.62x39mm round. The use of a case with near similar dimensions made the conversion of the AKM rifle much easier. Compared to the 7.62x39mm round the 5.45mm round is much thinner and lighter, while being more streamlined and slightly longer. The reduced weight results in a higher velocity, but reduces the energy and lethality. There is an air cavity in the nose that makes the 5.45mm tumble and yaw upon impact, which moderately increases lethality.
The 5.45mm round is associated with the AK-74 assault rifle for which it was developed. It is also used in the AKS-74U sub machine gun variant and the RPK-74 light support weapon variant of the AK-74. The 5.45mm round is also in use with various other weapons of Eastern European origin, many of which are also based on the Kalashnikov design.
When fired from the AK-74 the 5.45x39mm 7N6 bullet has a muzzle velocity of 900 m/s and energy of over 1.400 J. At 400 meters these figures are reduced to 550 m/s and over 500 J. Compared to the older 7.62x39mm round it replaced the 5.45mm has less energy and not as good in penetrating brush or wood. On the other hand the 5.45mm round has a flatter trajectory, is more accurate and is better at penetrating steel.
The first and foremost user of the 5.45x39mm round was the USSR, using it in the standard issue AK-74 assault rifle. The 5.45mm round remains in widespread use and is very common in Eastern Europe and the former USSR. It is in limited use in the rest of the world by those nations that use 5.45mm weapons of Eastern European origin.
5.45x39mm Soviet 7N6M cartridge.
Source: Grasyl - © CC BY-SA 4.0
The 5.45x39mm was introduced with the AK-74 in 1974.
Light machine gun based on the AK-74.
Compact assault rifle based on the AK-74.
Romanian Kalashnikov pattern rifle chambered for 5.45mm.
Modernized AK-74 with folding stock, sight mount and polymer furniture.
The AK-105 is a carbine in the AK-100 family of assault rifles that is chambered for 5.45x39mm.
Russian assault rifle with unique design, having a two round burst fire mode at very high cyclic rate of fire.
The 5.45x39mm Soviet round was inspired by the 5.56x45mm high velocity intermediate cartridge introduced by the US in the mid 1960's
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