Reason could not. In 1993, they were convinced they would have the Second Amendment all but repealed by now. They were sure that with Clinton in the White House, all the gun control they wanted was a done deal. But then came the elections of 1994 and it all came to a screeching halt. The assault weapon ban was a joke because it only affected weapons produced after Sept. 23, 1994.
All firearms produced prior to that are exempt.
The background check was OK, but in order to get that, they had to give up their precious waiting period which did not make them happy. Now comes the so-called Juvenile Crime Bill and with the prospect of another Bush in the White House, they are afraid this may be their last shot for some time. That probably depends on what happens to Congress, but I hope they are correct. As for the bill itself, about all that's left of the gun legislation is a ban on imported magazines over 10 rounds, making it illegal for persons under 21 to possess a handgun, and background checks on all sales at gun shows. My guess would be the background checks at gun shows.