I made a list earlier. Here is a re-hash, with a little extra added:
#1 thing that would reduce gun murders (BY FAR): Law Enforcement and the FBI starts doing their job. The vast majority of gun murders are inner city by felons who shouldn't have guns. Nobody ever goes to confiscate weapons when people are convicted of felonies.
#2 our gun murder rate is at an all time record low going back to the 1800s, when their data collection was probably not even good in the first place. So gun murders are nothing new and have dropped substantially in the United States. But the TYPE of targets have changed to softer targets like schools (colleges, elementary schools, movie theaters) and other "gun free zones" where the criminals know they probably won't find any resistance. Hire an armed resource/police officer for every school. NOT TEACHERS. NOT STUDENTS. Put metal detectors at every entry point. Create a safe perimeter around all schools (ie security with badge scans, etc.) for entry.
#3 partly overlaps with #1, but get more aggressive above inputting police and mental health contacts into the background check database. This is probably where legislation is needed and it will start lawsuits for infringing on the 2nd and 4th and 1st amendments, but I think you can make a public welfare and safety argument that even if you can't successfully prosecute someone for making terroristic threats (or similar) that results in a felony and loss of guns, high levels of violent behavior and mental health issues should get someone a 5 year time-out or something like that. Guns confiscated for 5 years, 5 year probation.
None of these actually address the underlying problem, which is why do people kill in the first place. That brings me to #4, which will do infinitely more to prevent these before they even get started. And that is the destruction of our moral and traditional values and the disintegration of the family. The statistics of those raised without a father (for example) is many many many many times larger to be involved in violence, crime, and all sorts of other dysfunctional behavior. We have a culture of moral relativism now. There is no clear right and wrong, its only right or wrong individual to individual in what they think and believe. And that's a dangerous recipe. In another post I listed that kids raised in single family homes are 10-20 times more likely to get arrested, end up in prison, commit violence against another person, have a mental illness, and so on.
In terms of actual gun control, I can't think of anything that will help that is actually possible. You can't make guns disappear. You're not going to be able to confiscate them. So all this talk of banning semi-automatic guns is nonsense. Its what everyone owns, ain't going to happen. Just on the newswire is that Trump is moving to ban bump stocks. More non-sense. I mean, I don't own guns, so none of this will affect me directly, but we have 1 single event out of the 100,000 gun murders in the last decade that came from bump stocks. And as HILLARY CLINTON HERSELF SAID, bump stocks prevented the Las Vegas attack from being more deadly. Bump stocks make aiming all but impossible. They also heat up the gun barrel much more quickly leading to much more rapid failure of the gun. If the attacker there had used a silencer or even just a regular gun and could have aimed, he would have been able to kill more than 58. Think about it - he had 60 minutes to shoot, and unloaded over 1,000 rounds INTO A CROWD OF PEOPLE unable to leave due to high fence and only a couple exit points. And he killed 58. Pitiful. So in the last few years our only moves on gun control serve to make deaths more likely. LOL.