Seems like exactly the opposite is true. Where specific bills have reached the floor, they've
passed. The tactics of the opposition are to use procedural control and veto power to prevent these from becoming laws. The assault weapons ban of 1994 was a successful law, and would have removed access to almost all the weapons used in the recent attacks. It had a sunset provision, and expired in 2004. But it passed, and it worked.
It's a common founding myth among gun rights people that "The American People" are pro-gun, but it's just not really true. It's a particular driving issue for a particular subset of the republican base, and beyond that opinions aren't as strong, but are broadly pro-gun-control.