The AKU-94 is a bullpup conversion kit (built and originally sold as a kit by K-VAR) for the AK type rifle, Both the European style AKs (like the Romanian AKs or Egyptian Maadis) and the Chinese style of AK rifle (Type 56) can fit into the kit. In the Mid-2000s, KVAR stopped making and selling the AKU-94 conversion kit. All remaining kits were purchased by Century Arms International, and subsequently used to 'spruce up' AK rifles with a futuristic bullpup look. Currently various imported AK rifles (mostly WASRs) with kit installed, is sold by Century Arms International. This bullpup configuration retains the standard barrel length but the design makes the AK rifle more compact making it more suitable for close quarters battle.
Once the manufacturing difficulties of non milled receivers 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 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. It was also roughly one-third lighter than the previous model.