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 the manufacturing difficulties of non-milled receivers had been overcome, a redesigned version designated the AKM (M for "modernized" or "upgraded"; in Russian: []) 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 fully 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 fully automatic fire. The rifle was also roughly one-third lighter than the previous model. Most licensed and unlicensed productions of the Kalashnikov assault rifle abroad were 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 often colloquially referred to as "AK-47s" in the West and some parts of Asia, 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 differences between the milled and stamped receivers includes 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. Replacement In 1974, the Soviets began replacing their AK-47 and AKM rifles with a newer design, the AK-74, which uses 5.45×39mm ammunition. This new rifle and cartridge had only started to be manufactured in Eastern European nations when the Soviet Union collapsed, drastically slowing production of the AK-74 and other weapons of the former Soviet bloc. Design The AK-47 was designed to be a simple, reliable fully automatic rifle that could be manufactured quickly and cheaply, using mass production methods that were state of the art in