AKM, which was first finalized, was adopted by the Soviet Union in 1959. The main improvements are as follows:
1. The weight of the rifle was reduced, mainly by using a large number of stamping parts, and riveting was changed to welding. For example, the barrel sleeve and tailstock were spot-welded on a 1mm thick U-shaped casing, and the frame-bolt guide rail was also stamped parts and spot-welded on the inner wall of the casing; The magazine was changed to light alloy, which can be used with the original steel magazine. In the later stage, a magazine molded by glass fiber plastic was developed, which can also be used completely. The stock, the guard and the grip are made of synthetic resin.
2. The surfaces of the bolt and the bolt frame are phosphatized, and there are four semicircular notches at the front end of the piston barrel, which are just matched with the notches similar to the air guide hoop; There is a small magazine positioning slot on both sides of the case, and there are reinforcing ribs on the case cover.
3. The hammer is equipped with a Hammer Delay consisting of five parts, which is located near the trigger.
4. The range of the scale is increased, and the scale is divided into 2 ~ 1 m and one is divided into 2 m; Both the cylindrical sight and the U-shaped notch photogate have reversible accessories, which contain fluorescent material radium 221 for aiming at night.
5. switch to a new multifunctional bayonet (type 2 bayonet).
6. There are finger grooves on the guard wood, which is convenient for the shooter to control the weapon when shooting repeatedly.
The biggest difference between Model 3 AKM and Model 1959 AKM is that an oblique notch muzzle anti-jump device is designed, which is screwed on the muzzle to improve the dispersion accuracy during continuous firing, and the length of the whole gun is increased to 88mm. Just like the case of AK-47, because the type 3 AKM is widely equipped by Soviet troops and other eastern camps, some people mistakenly think that AKM must have a diagonal anti-jump device.
In addition, a new bayonet (type 3 bayonet) was designed for this model, and the shape of the handle was changed, and the plastic handle and scabbard were used for the first time. At present, most of the AKM we see are of this type with anti-jump device. Later, many modifications of AKM appeared based on this type. Among them, AKMC is a folding metal stock (AKMS in English), and there are two types of folding stock: one is made of two struts and folded under the case, which is a common AKMS model; The other is folded to the right of the casing with a reinforced guard in the middle. AKMH (AKMN in English) is a model with night vision sight, and there is also a short barrel AKMCY (AKMSU). After the Soviet army was equipped with AKM, other Warsaw Pact countries began to equip it.
the earliest AK-74 was developed for mechanized infantry and finalized in 1974. AK-74 is based on AKM, and their principles, locking mechanism, ammunition supply mode and firing and launching mechanism are exactly the same. However, in order to launch a small-caliber 5.45mm M74 bomb, the machine gun, bolt machine and air guide hoop were improved accordingly. Among them, the winding distance of barrel rifling is shortened, which makes the warhead rotate at a high speed and fly stably. In addition, the diameter of the gun body is correspondingly reduced, so that the weight ratio of the gun frame to the gun is increased to 6∶1(AK-47 is 5∶1). The advantage of this ratio change is that the rifle automatic machine is more reliable when firing, but the disadvantage is that the strength of the shell pulling assembly is higher, so the parts with high strength requirements such as the gun frame and shell pulling hook are redesigned. In addition, AK-74 also chrome-plated the gun bore, and added an efficient muzzle device, which is the biggest difference between AK-74 and AKM in appearance.
The new muzzle device is cylindrical in appearance, completely machined, with a length of 81mm and a diameter of 25.8mm and a double-chamber structure inside. Two sides of the front chamber are respectively milled with a large square opening, and the back section of the opening is cut with a zigzag groove; The back chamber is provided with three air holes with a diameter of 2.5mm, which are distributed on the upper surface and the right side surface. According to the principle of gas dynamics, the gunpowder gas ejected from the muzzle carries out two impacts and two expansions in this muzzle device. When the gas passes through the back chamber, some gas is ejected from the three vent holes in the back chamber to achieve the comprehensive functions of braking and damping; When passing through the front chamber, the groove at the rear end face of the large opening will make the gas flow 25 degrees, so that enough gas will recoil on the front end face of the opening, further reducing the recoil force. In addition, spraying gas to the upper right can reduce the jump when shooting at the muzzle, which is also conducive to improving the shooting accuracy. Due to the low recoil of small caliber ammunition and the effect of this muzzle device, the accuracy of AK-74' s continuous firing and dispersion is greatly improved. However, although this brake has obvious braking effect, it has another disadvantage, that is, the muzzle flame will be more obvious, especially when shooting in the dark.