Design background
During World War II, the Germans first pioneered the assault rifle concept, based upon research that showed that most firefights happen at close range, within approximately 300 meters. The power and range of contemporary rifle cartridges was excessive for most small arms firefights. As a result, armies sought a cartridge and rifle combining submachine gun features (large-capacity magazine, selective-fire) with an intermediate-power cartridge effective to 300 meters. To reduce manufacturing costs, the 7.92x57mm Mauser cartridge case was shortened, the result of which was the lighter 7.92x33mm Kurz.
The resultant rifle was the Sturmgewehr 44 (StG44). An earlier firearm, the Italian Cei-Rigotti combined similar features but suffered poor reliability and ejection mechanism, as well as inferior magazine capacity. Towards the end of the war, the Germans fielded the StG44 against the Soviets; the experience deeply influenced Soviet military doctrine in the post-war years.
Mikhail Kalashnikov began his career as a weapon designer while in a hospital after he was shot in the shoulder during the Battle of Bryansk. After tinkering with a sub-machine gun design, he entered a competition for a new weapon that would chamber the 7.62x41mm cartridge developed by Elisarov and Semin in 1943 (the 7.62x41mm cartridge predated the current 7.62x39mm M1943). A particular requirement of the competition was the reliability of the firearm in the muddy, wet, and frozen conditions of the Soviet front line. Kalashnikov designed a carbine, strongly influenced by the American M1 Garand, that lost out to the Simonov design that later became the SKS semi-automatic carbine. At the same time, the Soviet Army was interested in developing a true assault rifle employing a shortened M1943 round. The first such weapon was presented by Sudayev in 1944, but trials found it to be too heavy. A new design competition was held two years later where Kalashnikov and his design team submitted an entry. It was a gas-operated rifle which had a breech-block mechanism similar to his 1944 carbine, and a curved 30-round magazine.
Kalashnikov's rifles (codenamed AK-1 and −2) proved to be reliable and the weapon was accepted to second round of competition along with designs by A.A Demetev and F. Bulkin. In late 1946, as the rifles were being tested, one of Kalashnikov's assistants, Aleksandr Zaytsev, suggested a major redesign of AK-1, particularly to improve reliability. At first, Kalashnikov was reluctant, given that their rifle had already fared better than its competitors. Eventually, however, Zaytsev managed to persuade Kalashnikov. The new rifle was produced for a second round of firing tests and field trials. There, Kalashnikov assault rifle model 1947 proved to be simple and reliable under a wide range of conditions with convenient handling characteristics. In 1949 it was therefore adopted by the Soviet Army as '7.62mm Kalashnikov assault rifle (AK)'.
Design concept
The AK-47 is best described as a hybrid of previous rifle technology innovations: the trigger, double locking lugs and unlocking raceway of the M1 Garand/M1 carbine, the safety mechanism of the John Browning designed Remington Model 8 rifle, and the gas system and layout of the Sturmgewehr 44. Kalashnikov's team had access to all of these weapons and had no need to "reinvent the wheel", though he denied that his design was based on the German Sturmgewehr 44 assault rifle. Kalashnikov himself observed: "A lot of [Soviet Army soldiers] ask me how one can become a constructor, and how new weaponry is designed. These are very difficult questions. Each designer seems to have his own paths, his own successes and failures. But one thing is clear: before attempting to create something new, it is vital to have a good appreciation of everything that already exists in this field. I myself have had many experiences confirming this to be so."
Receiver development
There were many difficulties during the initial phase of production. The first production models had stamped sheet metal receivers. Difficulties were encountered in welding the guide and ejector rails, causing high rejection rates. Instead of halting production, a heavy machined receiver was substituted for the sheet metal receiver. This was a more costly process, but the use of machined receivers accelerated production as tooling and labor for the earlier Mosin-Nagant rifle's machined receiver were easily adapted. Partly because of these problems, the Soviets were not able to distribute large numbers of the new rifle to soldiers until 1956. During this time, production of the interim SKS rifle continued.
Once manufacturing difficulties had been overcome, a redesigned version designated the AKM (M for "modernized" or "upgraded"—in Russian: (Автомат Калашникова Модернизированный [Avtomat Kalashnikova Modernizirovanniy]) was introduced in 1959. This new model used a stamped sheet metal receiver and featured a slanted muzzle brake on the end of the barrel to compensate for muzzle rise under recoil. In addition, a hammer retarder was added to prevent the weapon from firing out of battery (without the bolt being fully closed), during rapid or automatic fire. This is also sometimes referred to as a "cyclic rate reducer", or simply "rate reducer", as it also has the effect of reducing the number of rounds fired per minute during automatic fire. It was also roughly one-third lighter than the previous model. Both licensed and unlicensed production of the Kalashnikov weapons abroad were almost exclusively of the AKM variant, partially due to the much easier production of the stamped receiver. This model is the most commonly encountered, having been produced in much greater quantities. All rifles based on the Kalashnikov design are frequently referred to as AK-47s in the West, although this is only correct when applied to rifles based on the original three receiver types. In most former Eastern Bloc countries, the weapon is known simply as the "Kalashnikov" or "AK". The photo above at right illustrates the differences between the Type 2 milled receiver and the Type 4 stamped, including the use of rivets rather than welds on the stamped receiver, as well as the placement of a small dimple above the magazine well for stabilization of the magazine.
In 1978, the Soviet Union began replacing their AK-47 and AKM rifles with a newer design, the AK-74. This new rifle and cartridge had only started being exported to eastern European nations when the Soviet Union collapsed, drastically slowing production of this and other weapons of the former Soviet bloc.
| Receiver type | Description |
|---|---|
| Type 1A/B | Original stamped receiver for AK-47. -1B modified for underfolding stock. A large hole is present on each side to accommodate the hardware for the underfolding stock. (this naming convention continues with all types) |
| Type 2A/B | Milled from steel forging. |
| Type 3A/B | "Final" version of the milled receiver, from steel bar stock. The most ubiquitous example of the milled-receiver AK-47. |
| Type 4A/B | Stamped AKM receiver. Overall, the most-used design in the construction of the AK-series rifles. |
