I think one factor that contributed was that the full agenda of gun control was revealed. At that time, there was (and still is) a statistical case for stronger controls on handguns as contributory to crime. In fact, the leading anti-gun org called itself "Handgun Control, Inc.". And then some bright boy inside HCI came up with the idea of an "assault weapons ban" on semi-automatic long guns. And indeed, for a while, it looked like that propaganda shift would be successful.
Problem was, there was NO evidential case that could be made for banning ANY long guns.....they were (and are) minor factors in crime.
And this it became clear that the REAL agenda of gun control was the eventual elimination from society of any and all firearms.
Enough people caught on so as to blunt the AWB legislation and get a cutoff date included after which the ban would "go away". Soooo.......society did the experiment. The AWB had zero effect on gun crime rates, and was not re-instated when it reached it's "sell-by" date.
And that was the high-water mark of gun control.
It was a major reason the Democrats lost control of the House for the first time in 40 years.
The message sent was not subtle.
You are right about the assault weapons ban having no effect on crime rates. Most crimes involving guns involve handguns presumably because they are more easily concealed.
In that sense, handgun controls are statistically more sensible. Of course, violent criminals do not normally try to obtain guns legally. It makes sense that a criminal does not want to fill out paperwork and undergo a background check for a gun that would directly tie them to a crime. Convicted felons could not pass a background check anyway.
That is why criminals use straw buyers, steal guns, and get guns from black markets; so, then the question becomes what kind of controls will we apply?