Two points. One, these polls give one an idea of how people might feel about an idea in principle, but don't tell you how people feel about the implementation of the idea as a law. Many of the gun control bills that are proposed have flaws that disproportionately affect law-abiding gun owners, and given the general skepticism of the efficacy of gun control laws here, the bills fail to advance.
The second point is that it isn't informative to average across the US to make statistical inferences: it's too heterogenous. Most violent crime in the US (keeping in mind different countries define violent crime uniquely and report it with varying rates) is cultural and is highly focal in limited parts of cities. Even with firearms, many parts of the US are statistically similar to similar areas in Europe when considering violent crime.
The second point is that it isn't informative to average across the US to make statistical inferences: it's too heterogenous. Most violent crime in the US (keeping in mind different countries define violent crime uniquely and report it with varying rates) is cultural and is highly focal in limited parts of cities. Even with firearms, many parts of the US are statistically similar to similar areas in Europe when considering violent crime.