The term "assault weapons" as it is currently used is (puposely) misleading.
"Assault weapon" is merely a catchy term which was conjured up by the gun control lobby to aid in its efforts to demonize these guns.
An assault rifle has a mechanism that allows for fully automatic firing, so that as long as the trigger is squeezed, cartridges will continue to be fired in rapid succession until the supply of ammunition is exhausted. These types of firearms have been heavily regulated since 1934, and are not addressed at all in the legislation banning "assault weapons." This is a very important point, as the average person would have a difficult time distinguishing between side by side photos of a fully automatic assault rifle and a semi-automatic look-alike.
But despite the similar or identical appearances to military firearms, the functionality of "assault weapons" is no different than any other semi-automatic, which have been available for 100 years. And though the label "assault weapons" is relatively new, this type of firearm is not. For example, Colt began making the AR-15 Sporter, a semi-automatic version of the military M16, almost 40 years ago. The venerable M1 Garand, used by our troops in WWII (and, by the way, is significantly more powerful than more modern "assault weapons"), has been available to civilians for even longer.
http://www.awbansunset.com/whatis.html
In other words, an "assault weapon" is a "machinegun". The AK-47 and Uzi banned in 1994 were not machineguns, and are functionally identical to other firearms which were not banned under that legislation. The Bushmaster used by the D.C. "sniper" (another misnomer) was not a machinegun. John Allen Muhammed and Lee Boyd Malvo could have accomplished the same murders with any number of other weapons not banned under the 1994 law, including a single shot rifle.
For example, in his book, "Guns: Who Should Have Them?" author David B. Kopel illustrates this point by writing:
Persons who do not know much about guns may be forgiven for thinking that "assault weapons" are machine guns; these people are victims of what has been, in some cases, a quite deliberate fraud. For example, CBS's Chicago affiliate, WBBM-TV, showed a reporter buying a (then legal) semi-automatic Uzi carbine (small rifle); the report later showed an automatic Uzi being fired, and viewers were never informed that the guns had been switched.
and:
People who get most of their knowledge about guns from television may have different impression of the lethality of "assault weapons" as the result of bad reporting on the part of some stations. For example, in early 1989, when 'assault weapons' had just become a major interest of the media, a Los Angeles television station arranged with the Los Angeles County Sheriff's Department for a demonstration of the "awesome power" of "assault weapons." Using a rifle like the one used by Patrick Purdy in the Stockton shootings, an officer shot a watermelon that had been set up on a target stand. The bullet punched a hole the size of a dime in the watermelon, leaving the large fruit otherwise intact. The television reporter complained that the result was "visually unimpressive." The officer obligingly unholstered his service gun (a Beretta pistol, not an "assault weapon"). Loaded in the officer's pistol were high-performance Winchester Silvertip STHP rounds. He fired once, and the watermelon exploded into tiny fragments. By the time the "demonstration" had been edited for broadcast, viewers saw only the officer holding the "assault weapon" and then the exploding watermelon. Viewers were deliberately misled into believing that the "assault weapon" had caused the explosion.
http://www.awbansunset.com/history.html
The focus, hype and hyperole on the AK-47 and Uzi are a red herring designed by the anti gun lobby for the purpose of building public sentiment against these firearms on the basis of their appearance only.