An ad on my Facebook Scrabble game pleaded that "Gun violence is out of control." Actually, it is lower than it has been in the past, but on one level, it's always out of control. The only controlled gun violence would be done by the police or the military.
To the extent that we have freedom, crime is out of the control of the government; we're not to the Minority Report level where they keep you from doing crimes ahead of time. A ban on firearms merely takes such weapons out of the hands of law-abiding citizens; states with more permissive gun laws actually have less gun violence per capita.
The vast majority of gun crime is gang-related. That's not going to be easily stopped by banning big clips or whatever makes Sen. Feinstein uneasy. That takes changing the youth and young adult culture, mostly (but not exclusively) in tougher parts of town; for most gangsters, firearms violations will likely be a mere tack-on to other more-serious charges they face if and when the cops catch up to them.
We have a small handful of mass murders each year, but the bigger problem with gun crime isn't the exurban psycho going postal at a school or theater every so often. Detroit had 378 murders this year; that's over a Sandy Hook a month, but it's generally done one or two at a time, so we don't have the center-left punditry up in arms over it.
Any gun control law that passes Second Amendment muster won't make much of a dent in that. It might slow down the otherwise law-abiding gunner from doing damage, but it won't do much to stop the few-at-a-time violence that claims far more folks than the big events that make the news.