Definition of Assault Weapon
The law created a definition of assault weapon: Certain models (all of which apply to only semi-automatic weapons), such as the Colt AR-15, TEC-9, all Kalashnikovs (including the AK-47), Uzi, and others were banned by name; other firearms were banned for having certain features:

Semi-automatic rifles with detachable magazines and two or more of:

folding or telescoping stock
conspicuous pistol grip
bayonet mount
flash suppressor, or threaded barrel designed to accommodate one
grenade launcher

Semi-automatic pistols with detachable magazines and two or more of:

magazine that attaches outside the pistol grip
threaded barrel to attach barrel extender, flash suppressor, handgrip, or silencer
barrel shroud that can be used as a hand-hold
unloaded weight of 50 oz or more
a semi-automatic version of an automatic firearm
(all but the last pistol feature are found in the pre-ban TEC-9, the probable inspiration for that section of the law)

Semi-automatic shotguns with two or more of:

folding or telescoping stock
pistol grip
capacity of more than 5 rounds
detachable magazine
On March 2, 2004 (108th Congress, 2nd Session), Senator Diane Feinstein (D-CA) added a 10-year extension to the 1994 Assault Weapons Ban, Amendment 2637, to S.1805, the Senate's gun manufacturer immunity from liability bill. While the amendment was agreed to by a vote of 52-47, S.1805 picked up several other amendments, and the National Rifle Association withdrew its support of the bill. The sponsor Larry Craig (R-ID) asked for a vote, and S.1805, with the Feinstein Assault Weapon Ban renewal amendment, was voted down 8-90. S.1805 was widely hailed by Democrats as the only viable vehicle for a renewal of the AWB before its expiration.