The following rifles were designed and are still produced in Russia by several manufacturing companies under contract with the government.  These are the original AK rifles that all others are coped from.

AK-47
Adopted by the Russian Army in 1949, the AK-47 military assault rifle is one of the, if not the, most famous rifle in all of history.  It was designed to fire the Russian Standard 7.62x39 military round, and is the main reason that round is still available to day (the SKS also fires the same round).  The weapon is capable of firing in semi-automatic and automatic modes, with a total throughout put capability of 600 rpm.  The Kalashnikov action that the AK-47 rifle and its offspring are built around is very violent--this is why the rifle works without flaw in almost any condition, from Siberia to the Middle East.  It takes a lot to stop an AK rifle from working, unlike the American AR-16/M16, which has a tendency to jam often.  The AK-47 is, in fact, found on the flag of some nations.

AK-74
Adopted by the Russian Red Army in the 1970s, the AK-74 military assault rifle is a twin of the original AK-47 that fires the newer 5.45x39 military round.  The only real difference is the cartridge in this case.   Since the original introduction of the rifle, the option of a composite frame set as opposed to the traditional wooden frame sets was also introduced, and became available for both the AK-47 and the AK-74.

AK-100 SERIES
The AK-100 series of rifles are the newest original Kalashnikov rifles, currently in production in Russia, by the IZHMASH company.  These are modernized AK assault rifles/sub-machine guns--and they are available in three chamberings: traditional 7.62 x 39 mm, modern 5.45 x 39 mm, and the new 5.56 x 45 mm NATO.  These new rifles all feature a black/composite finish, folding stocks, and are available in several barrel lengths.