There are relatively small numbers on both sides who care deeply about the fine points of this law and huge number who really haven’t paid attention but will answer yes if ask them about specifics. Passionate but relatively small special interest groups from both sides can block or advance issues even if the majority of country doesn’t agree with them as long as the majority doesn’t feel strongly about it. The majority of the country may have strong feeling about gun control but not the issues this bill address. Better salesman ship could have helped with that.
Not surprisingly I know a large number of conservative who were against it but when I ask them if they would support limiting magazine capacity on weapons over a certain caliber and making online sellers and gun shows follow the same rules as guns stores the majority say yes.
If they had just tried to sell these common sense changes straight up without all of the passion and distraction you get from trying leverage tragedies the new law would not have even prevented they might have had a chance of getting the law passed. There would still have been resistance but they could have avoided the knee jerk reaction of the guns right supporters to resist the knee jerk reaction of the gun control group to use every tragedy to advance their agenda.